Misfire on Cylinders 5, 7, 8 (FIXED! Broken Valve Spring)

[PAFirefighter11]

Slight Update: When I unplugged the MAF the misfire code and blinking CEL disappeared. It still has a misfire, but nowhere near as bad. I tried installing a used MAF out of a working vehicle. Plugged it in and the CEL blinking, misfire code, and horrible drive-ability came right back.

I've been posting on my Trans Am / LS1 specific forums and so far no luck. So, I figured I'd post here for the hell of it.

This is on my '98 Trans Am. On July 25th, 2012 I was driving in to work and I noticed some hesitation in 6th gear at 65 MPH. Wasn't a big deal I thought. Then, I noticed it at lower gear, and now while accelerating in every gear. It's like a full auto AK-47, for example, in terms of rate (not loudness). It idled fine.

My SES light has been on for a year now now. It's telling me the driver side cat is bad. On my drive to/from the Hamptons (On the weekend prior to 7/25/12) I hit 2389048923480234 bumps, pot holes, etc., mainly on the Belt Parkway & Staten Island Expressway. Is it possible it rattled my cat apart and is now clogged up?

Fast forward to a couple weeks ago. Things are MUCH, much worse. Car won't idle properly. Can barely drive it. It's missing BAD. Above 35 MPH the CEL blinks, which as we all know is not a good thing. Here is are two crappy videos to demonstrate what's happening (at idle at least):
http://www.youtube.com/watch?v=_n_8yLhQNtU

http://www.youtube.com/watch?v=4sOfqrMLJlc


2 weeks ago I drove the car to a guy on Yellow Bullet. He is an engine builder and has done several LS1 and other cars over the years. He hooked it up to a SnapOn scanner to monitor the car while running. I think it's the SnapOn Solus. Hooked up fine while the car was off. Then when the car was running it had several issues trying to connect. Finally it worked and we got this...

-Cyl #5 misfire
-Cyl #7 misfire
-Random Cyl #8 misfire
-Random Cyl #6 half fire

CEL is on. Codes are only showing P0420 (Catalyst efficiency below threshold on bank 1). However, o2 sensors are reading as normal. Cat temps are running within normal ranges as well (Checked with an infrared thermometer). Other code is "Cylinder misfire detected".

Other issues:

-Third brake light sometimes illuminates like a rear tail light. On while lights are on, then brighter when the brakes are applied. I have an LED 3rd brake light installed btw.
-Turn signals are also acting weird. They blink quickly, slowly, normal, and anything between.

I changed the plugs to NGK TR-55 plugs. Wires are brand new as well from Vengeance Racing. We have checked the injectors & coils. Used some from other working vehicles and they did not change anything. They are fine. Also got a noid light on the injector wiring harness. Checked fuel pressure and it's good, in the green at 55 psi. So I am thinking harness or computer? I am borrowing a computer from my buddy who removed it from a '98 Camaro SS.

2 interesting things. First, I just noticided this on the ECU I pulled from my car is a reman:
http://ls1tech.com/forums/attachment.php?attachmentid=385950&dateline=1357256003

Second here's the corrosion that's all over both the ECU and the harness side (I cleaned this all up since the photo):
http://ls1tech.com/forums/attachment.php?attachmentid=385951&dateline=1357256003

Also figuring maybe grounds? I removed the 4 easily accessible grounds: Driver side strut tower, driver side front next to the intake, passenger side strut tower, passenger side front next to the intake. I filed down the grounds metal contacts and wire brushed them as well.

Started up the car and it ran basically 99%! I took it for a 0.5 mile drive and it slowly got worse. At stops it would almost stall. I brought it back and parked it. It seemed to get worse the longer it was running. However, overall it seems much quieter and seems to run much smoother as well (This is with the other ECU).

Should I just replace the driver side cat and see if that fixes things?

I REALLY want to be able to enjoy my car again, but I haven't been able to drive it in months 'cause of this crap. Thanks!

[jpalamar]

Did you wiggle the cat to see if anything is loose in it?

[PAFirefighter11]

Did you wiggle the cat to see if anything is loose in it?

Can't wiggle it, it's in there good lol. I did a knock test on it and there was no rattling of the innerds that I could hear.

[Nick 95 6sp]

Even though you mentioned changing plugs, from the way you described your sequence of events I can't tell if you changed plugs and the misfire was still there.

Also, if / when you pulled the first set of plugs out that were misfiring, how did the plugs look? Any pics of the electrode end of those plugs?

[OutToWinPAHC]

interesting its the total 4 rear cylinders on two banks, and I know those two suck to get to in the rear on your car. Id disconnect the battery, unplug the ECU and clean they terminations at the ecu, and at the coil pack to harness, and coil harness to main harness connections. The LS coils have 4 wires Power 12V, Gate drive, ECU ground, and chassis ground. I would then put it together, put it in the on position and check voltage to both grounds at the 4 wire plug to the coil.

The other thing is your code can also sometimes be associated with crank position not learned, have you seen this code at all?

[PAFirefighter11]

I have 109,XXX miles and do not think that the prior owner changed the wires. The plugs are half and half. I just changed the wires to Vengeance Racing:
http://pafirefighter11.smugmug.com/photos/i-bCMPT8c/0/L/i-bCMPT8c-L.jpg

Also running new TR55 NGK plugs gapped to .055. The gap of the old plugs was at .085!

These are the plugs, set up in cylinder order. Top plugs are the front of the vehicle:
http://pafirefighter11.smugmug.com/photos/i-kLNnwFP/1/L/i-kLNnwFP-L.jpg

I was unable to reach cyl #8. I changed the plugs and wires after the misfire began. It did not change anything after the plugs/wires were installed.

I've never had any other codes than:
P0420 - Catalyst efficiency below threshold (original code I've had for some time)
P0300 - Random misfire detected
P0140 - o2 circuit blah blah (from when I disconnected the driver side downstream o2 sensor to check it)

[SHOdude]

Dude change your ****ing cat.. it could be causing all of this sending false readings to your adaptive learning and making it run rich or lean and messing all your crap up. Those plugs are pretty burnt up too, are you burning oil? Did you clean any of them? Your running a bit rich and not getting enough spark by the looks of the plugs too.

[OutToWinPAHC]

those are his old plugs with 108K but yea he needs new wires for sure

[SHOdude]

those are his old plugs with 108K but yea he needs new wires for sure

possibly a distributor cap and rotor also, but he really needs to change that cat and by now the o2, if you have a laser thermometer point it about an inch before the cat (At full operating temp) and then an inch after the cat and you should see significant temperature difference

[OutToWinPAHC]

There is no distributor

[SHOdude]

There is no distributor

Coil pack then lol

[PAFirefighter11]

possibly a distributor cap and rotor also, but he really needs to change that cat and by now the o2, if you have a laser thermometer point it about an inch before the cat (At full operating temp) and then an inch after the cat and you should see significant temperature difference

However, o2 sensors are reading as normal. Cat temps are running within normal ranges as well (Checked with an infrared thermometer).

See above. And yes, no distributor. I have a coil pack on each cylinder. Swapped them around and the issue did not move.

Ordering up a Walker Y-pipe now.

[SHOdude]

Take same infrared, get to operating temp, check temp on each header to see if their misfiring or your getting a false reading.

[PAFirefighter11]

Take same infrared, get to operating temp, check temp on each header to see if their misfiring or your getting a false reading.

They def. are misfiring. Car barely runs/idles and shakes. It sounds like it has a nice cam haha. I'm just going to do a new Y pipe and see what happens after that.

[Big_Jim]

They def. are misfiring. Car barely runs/idles and shakes. It sounds like it has a nice cam haha. I'm just going to do a new Y pipe and see what happens after that.

I had a similar issue with my mustang. wound up replacing the camshaft position sensor and the crank angle sensor. Solved all my vehicles issues.

[OutToWinPAHC]

Codes are you best friend

[PAFirefighter11]

I had a similar issue with my mustang. wound up replacing the camshaft position sensor and the crank angle sensor. Solved all my vehicles issues.

Hmm, never crossed my mind since I am not getting those codes. Doing research on LS1 Tech and other LS forums now on the cam & crank sensors. It seems the symptoms my car is having could be the crank and/or cam sensors or a host of other issues. ..............

Gonna just do the Y pipe first and go from there I guess.

[Big_Jim]

my car never threw codes for the sensors. after reading up on symptoms and some diagnosis I decided to shoot in the dark and replace them.

[Honduh]

possibly a distributor cap and rotor also, but he really needs to change that cat and by now the o2, if you have a laser thermometer point it about an inch before the cat (At full operating temp) and then an inch after the cat and you should see significant temperature difference

wow. i see you giving me bad advice than good, give up.

those plugs look BEAT, but thankfully no signs of oil or coolant. if you put new plugs in pull them again and see if they are loaded up. also, to check for a clogged cat, pull the front o2 sensor and check for back pressure with a gauge, if its more than 2 psi you have a problem.

[SHOdude]

wow. i see you giving me bad advice than good, give up.

What was that? I cant tell if there's a typo in there or your missing a comma.

[Big_Jim]

What was that? I cant tell if there's a typo in there or your missing a comma.

If you are going to be a grammar Nazi, at least spell "you're" correctly.

[SHOdude]

If you are going to be a grammar Nazi, at least spell "you're" correctly.

No it was a serious question I dont know what he was going for there lol

[PAFirefighter11]

I just ordered the Walker Y pipe through my work. We will see if that helps things...

[Antonio]

when you said the O2 sensors were reading properly, did you just check for within range, or did you check to make sure the voltage being sent back was changing and not stuck? I still agree with everyone, get the cat issue fixed asap. It's kind of hard to help diagnose things when you have several things that all could lead to the same symptoms.

If for some reason you're unable to figure this out on your own and you get fed up and want a shop to fix it, you're not far from ECS. They're a fantastic shop and did my diff gears and fixed a coolant leak for me. Great work and great guys. They even washed my car, lol

[PAFirefighter11]

when you said the O2 sensors were reading properly, did you just check for within range, or did you check to make sure the voltage being sent back was changing and not stuck? I still agree with everyone, get the cat issue fixed asap. It's kind of hard to help diagnose things when you have several things that all could lead to the same symptoms.

If for some reason you're unable to figure this out on your own and you get fed up and want a shop to fix it, you're not far from ECS. They're a fantastic shop and did my diff gears and fixed a coolant leak for me. Great work and great guys. They even washed my car, lol

I had a buddy check. He has been an engine builder for decades and scanned it with his super expensive SnapOn scanner. He told me they look good, but didn't specify.

If I take it to a shop it'll most likely be CSP in West Chester or RPM in Delaware. May consider FAST or Import Intelligence, but prefer a shop that does mainly LS and similar cars.

My Walker Y pipe just shipped out from California, so it'll be here next week. I'll take it to my buddies shop and we'll get it up on the lift and installed. I'm hoping a bad cat is causing this issue, even though the infrared thermometer numbers seem fine.

[SHOdude]

Swarr auto does a lot of muscle cars, mostly mustangs though. I apprentice there, it's a good shop.

[Antonio]

Ecs is one of the best for LS motors....

My car personally was done by mike tiedemann of mcp competition engines. He works along with tune time performance in lakewood

[PAFirefighter11]

Thanks guys. Antonio, we lost our house down in Brick due to Sandy. Total teardown 'cause of water damage. So not sure what the deal is. I'm out here in West Chester, PA.

[Antonio]

ah, my mistake. Sorry man. Hope things go well for you and your family.

[devildog214]

just got done dealing with my misfire, did a opti and waterpump trying to chase a misfire that I caused. Used conventional plugs instead of platinums that were in it, and possibly might have just had bad new plugs from ac delco. Yeah do the y pipe why not. New plugs and wires next step. You said you just changed you wires not sure if thats before or after misfire, could very well have put in some faulty stuff like i did.

[PAFirefighter11]

just got done dealing with my misfire, did a opti and waterpump trying to chase a misfire that I caused. Used conventional plugs instead of platinums that were in it, and possibly might have just had bad new plugs from ac delco. Yeah do the y pipe why not. New plugs and wires next step. You said you just changed you wires not sure if thats before or after misfire, could very well have put in some faulty stuff like i did.

Y pipe is on, new upstream bank 1 o2 sensor is on (Denso). Still having the misfire.

New Walker Y-Installed. Still running like ass:
http://pafirefighter11.smugmug.com/photos/i-V5ZSg58/0/XL/i-V5ZSg58-XL.jpg

http://pafirefighter11.smugmug.com/photos/i-pqj6jPw/0/XL/i-pqj6jPw-XL.jpg

Driver side:
http://pafirefighter11.smugmug.com/photos/i-Vmmq4qj/0/XL/i-Vmmq4qj-XL.jpg

Pass. side:
http://pafirefighter11.smugmug.com/photos/i-4JDXLCq/0/XL/i-4JDXLCq-XL.jpg

Driver side pipe is this short:
http://pafirefighter11.smugmug.com/photos/i-FqHR3JV/0/XL/i-FqHR3JV-XL.jpg

Had to weld in some pipe:
http://pafirefighter11.smugmug.com/photos/i-TpGqtZk/0/XL/i-TpGqtZk-XL.jpg

http://pafirefighter11.smugmug.com/photos/i-nrDnLbD/0/XL/i-nrDnLbD-XL.jpg

http://pafirefighter11.smugmug.com/photos/i-Rp8CfRk/0/XL/i-Rp8CfRk-XL.jpg

Old o2:
http://pafirefighter11.smugmug.com/photos/i-SNxqSjx/0/XL/i-SNxqSjx-XL.jpg

New plugs and wires were installed after the misfire began. I'd say within the last 300-400 miles. NGK TR-55's gapped to .055. Vengeance Racing wires. I got to all the cylinders except #8.

I took the car to a local Performance shop that does tuning. He hooked it up to his laptop, fired it up and ran his programs. He said it's running lean (though smells of unburnt fuel). It's missing on 5, 7, and also on 6, 8. More-so on 5, 7. Driver side front o2 is bad, so I replaced it as I stated above.

It has some weird electrical things going on. Shifted into reverse and the speedo jumped to 20 MPH. Opened the cutout and the RPM's jumped 300 RPM. 2 weeks ago the speedo was reading WAY low. 42 MPH when doing 70 for example. The LED third brake light has been lit like a parking light, then when I hit the brakes it gets brighter. Odd. Turn signals will vary between staying solid and blinking slow or fast or any combo of the above. Etc.... This SUCKS. I just want the damn car to run again!

[Antonio]

ugh, electrical gremlins are the worst. Question: Saw you went with vengeance wires. Any reason why didn't use GMPP? Perhaps the wires could be arcing to the block or something else? I'd probably start at inspecting all the grounds and maybe possibly install a big 3 kit just for sake of mind. It couldn't hurt to have a big 3 kit anyway. If you didn't change anything that would cause a shorted wire harness or maybe a hairline break in a wire somewhere, it could be slowly degrading grounds or maybe heat melted something somewhere.

[PAFirefighter11]

ugh, electrical gremlins are the worst. Question: Saw you went with vengeance wires. Any reason why didn't use GMPP? Perhaps the wires could be arcing to the block or something else? I'd probably start at inspecting all the grounds and maybe possibly install a big 3 kit just for sake of mind. It couldn't hurt to have a big 3 kit anyway. If you didn't change anything that would cause a shorted wire harness or maybe a hairline break in a wire somewhere, it could be slowly degrading grounds or maybe heat melted something somewhere.

I went for Vengeance due to the lower ohms resistance. I found a nice thread on LS1Tech comparing approx. 10 or so different brands. I made my wire decision off of that testing. I'll double check at night but I don't think there is any arcing. Nothing I have seen. With it running like crap prior to (and after) the plugs and wires being changed I don't think the plugs/wires are to blame.

I checked and cleaned 5 of the easier grounds to get to: Sides of the intake (2), strut towers (2), frame rail by alternator (1). The grounds that the computer uses and other larger grounds are on the back of the motor. I can't really get my hands back there, or even inspect them for that matter. But I don't have the precise locations as to where they are. I posted on Tech asking for some photos but have yet to see anything...

[Antonio]

ah ok. I know there's a GM service manual torrent floating around that I believe you car should be included in. Could try searching for that in the mean time I guess, unless you get an answer on LS1tech

[SovXietday]

No it was a serious question I dont know what he was going for there lol

He's saying your advice is in left field. Most of his issues couldn't be caused by a bad cat.

Sounds to me like you are either chasing a bad ground, or have ECU issues. That ECU doesn't look so great, possible to find another one and swap it out to see if that fixes anything? That many cylinder misfires screams controller malfunction.

[PAFirefighter11]

He's saying your advice is in left field. Most of his issues couldn't be caused by a bad cat.

Sounds to me like you are either chasing a bad ground, or have ECU issues. That ECU doesn't look so great, possible to find another one and swap it out to see if that fixes anything? That many cylinder misfires screams controller malfunction.

Already swapped in ECU's from a '98 Camaro SS (Same as what the '98 Trans Am has). Didn't fix it. I think it may be a ground. I just can't find the grounds on the back of the motor. There are several and they are nearly impossible to get to it seems.

[PAFirefighter11]

Just wanted to update the latest. My buddy and I at work checked the wires running from the PCM to the coils. They all have continuity per our multi-meter. So, the wires are good from the PCM to the coils. One more thing ruled out I guess....

I'm going to check the wiring (visually at least) for o2s and crank sensor.

[jpalamar]

Get an OBD2 Bluetooth thingy on eBay for $15. Then download Torque on your smartphone. It will let you data log and read sensor reading. Might help you track things down.

[PAFirefighter11]

Seems the $15 ones are ****. I need this per Torque's website...
http://www.scantool.net/scan-tools/obdlink-sx.html?from=Torque

And no bueno for Mac compatibility lol. I wanted to be that cool guy with my Macbook hooked up to my car like in the moviessss. Oh well. I'll try the ****ty Chinese one for cheap and see how it works with my HTC Thunderbolt. Know anyone local who offers 'em? I hate waiting on shipping lol.

[jpalamar]

I have this one. Works perfectly.

http://www.amazon.com/gp/aw/d/B004KL0I9I/ref=mp_s_a_1?qid=1361360816&sr=8-2&pi=SL75

[PAFirefighter11]

Ordered it. It seems I have a 50/50 shot of it working for more than 5 seconds haha.

[Antonio]

I have the same bluetooth obd2 adapter and Torque pro and haven't had any issues thus far on about 3 or 4 different cars. Haven't really thoroughly played around with it and the logging functions, but works fantastic for displaying/clearing codes as well as monitoring voltage from O2 sensors. Found out one of my O2's on my daily altima might be dead. Doesn't vary voltage much....maybe just about +/- .03v. The other sensor varies by a much larger margin

[PAFirefighter11]

Got the reader today. It works great on my buddies WRX! I dropped off my Trans Am this morning at FAST in West Chester. We'll see if they can work their magic!

[jpalamar]

Told ya.

[PAFirefighter11]

Whatever! lol.

Thanks fella's. I'll do some more looking and a compression test soon.

I dropped it off at another local shop today. They put some time into it and are going to put some more work into it next week.

Just some info from my Torque app...

Freeze frame information:
------------------
Fuel Status = 0 byte
Engine Load = 6.667 %
Engine Coolant Temperature = 197.6 °F
Fuel Trim Bank 1 Short Term = 16.406 %
Fuel Trim Bank 1 Long Term = 24.219 %
Fuel Trim Bank 2 Short Term = -5.469 %
Fuel Trim Bank 2 Long Term = 13.281 %
Intake Manifold Pressure = 6.382 psi
Engine RPM = 1,608.25 rpm
Speed (OBD) = 34.797 mph
Mass Air Flow Rate = 155.214 cfm
Throttle Position(Manifold) = 11.373 %

End of report.

41* timing advance?!
http://pafirefighter11.smugmug.com/Automotive/1998-Pontiac-Trans-Am/i-N2rbV4m/0/L/487345_10151269396016080_705252989_n-L.jpg

[jpalamar]

Don't quote me on this because its been awhile since I've looked at tuning but I would think your timing should be like 1/2 that.

[Antonio]

yeah, that's gotta be a mistake on the part of the app. If that's correct that is wayyyyyyyyyyyyyyyyyyyyy off. Also, I'm not very knowledgeable about tuning, but should the short term fuel trim vary that much from bank 1 to bank 2?

[jpalamar]

Just for kicks... unplug your MAF and go for a short drive. See if it feels better and datalog to see if your timing drops back to 25-30*.

This is just screaming MAF to me for some reason.

[FAST of WC]

Just for kicks... unplug your MAF and go for a short drive. See if it feels better and datalog to see if your timing drops back to 25-30*.

This is just screaming MAF to me for some reason.

Unplugged MAF. Didn't make a difference


www.FASTofwestchester.com

[jpalamar]

Unplugged MAF. Didn't make a difference


www.FASTofwestchester.com

That sucks. It was a shot in the dark but I saw threads on HP tuners were MAF didn't throw a specific code but had similiar symptoms.

[SHOdude]

I know nothing about ls motors but have you tried checking with a timing light? I am starting to get familiar with tuning an I know for a fact that advance is way off if your app is correct.

Edit: did this start out of the blue or was it after an event? Also, was the motor ever pulled? This has gotta be some stupid simple fix

[Foolinaround]

^I was thinking timing as well.

[jpalamar]

That's def something to check next.

[TheAlchemist]

Parth throttle timing is in the high 30 to low 40 range. That's 100% typical.

The major ground you need to check is on the back of the driver's side head. Ther's a bolt that holds 3 ground wires. You should be able to reach back and feel it and see if it's tight. If you have access to a lift, put it in the air and it's clearly visible from underneath.

It does sound like an electrical gremlin. Pull wire loom and make sure you don't have a wire that has a fray in it that's shorting out.

[PAFirefighter11]

I did try a MAF out of my other car as well (Descreened though), but that didn't change anything. I also did the unplug and drove as well.

The fuel trims seem to be of huge concern per some of my expert friends. Not sure at what they should be, but they are definitely off.

I got to as many grounds as I could find. I did have the car up on a lift at my buddies shop and looked under it for the ground, but didn't find anything. I wasn't really "looking" though as we were doing the exhaust at that point.

Just for ****s and giggles... would adding new grounds to the motor possibly improve things, if indeed it is a ground that's bad? Or does that depend on which ground(s) is/are bad?



Unplugged MAF. Didn't make a difference


www.FASTofwestchester.com

I really appreciate you guys checking things out! VERY much appreciated. Hopefully next week brings good news.

[TheAlchemist]

The ground wires on the back of the head are critical and need to be grounded securely. You can't just add more grounds.

[PAFirefighter11]

The ground wires on the back of the head are critical and need to be grounded securely. You can't just add more grounds.

Got it. Just curious lol.

[SHOdude]

Also there should be a ground from the bottom of the block to the pass side frame rail

[Grounded]

Ive been reading through and following this. I talked it over with a few guys I work with. I work for GM. We're leaning towards a problem within the fuel rail.
If you can post freeze fram data at idle.

[PAFirefighter11]

Ive been reading through and following this. I talked it over with a few guys I work with. I work for GM. We're leaning towards a problem within the fuel rail.
If you can post freeze fram data at idle.

Thanks! I checked fuel rail pressure and it was showing 52 psi constant at idle. Didn't really change when I revved at idle. Have not individually checked anything else fuel-rail wise. It's definitely getting fuel to the plugs. I pulled the #5 plug just to check what it looked like. Looks brand new, minus some raw fuel.

I'll grab some fuel trim data tonight if I get a second. I'll FF at idle while firing properly (it does this for a few minutes at startup most the time) and then also while at idle while running like crap.

[Grounded]

I've found 2 people with a similar problem. one had a broken valve spring on #7. The other had a bad ground pcm to head.
Really what you need is someone with a TECHII which is a GM tool and this could more likely be figured out in a matter of minutes

[PAFirefighter11]

Freeze frame information @ idle:

------------------
Fuel Status = 0 byte
Engine Load = 2.353 %
Engine Coolant Temperature = 226.4 °F
Fuel Trim Bank 1 Short Term = -10.938 %
Fuel Trim Bank 1 Long Term = -7.812 %
Fuel Trim Bank 2 Short Term = -14.844 %
Fuel Trim Bank 2 Long Term = -8.594 %
Intake Manifold Pressure = 6.382 psi
Engine RPM = 755.5 rpm
Speed (OBD) = 0 mph
Mass Air Flow Rate = 53.824 cfm
Throttle Position(Manifold) = 0.392 %
End of report.

Per Tom Oates:
http://pafirefighter11.smugmug.com/photos/i-kjpLGwC/0/XL/i-kjpLGwC-XL.jpg

[Grounded]

Subject:

97 - 05 Vehicles with 4.8 5.3 5.7 and 6.0 Gen III V8 Engines and Misfires On One Bank






Models:

.



--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the described symptoms in the PI.

Condition/Concern:


Check Engine Light with a P0300 due to 2 - 4 cylinders misfiring on the same bank of the engine. DTCs P0171, P0172, P0174 or P0175 may also set for the misfiring bank.

Recommendation/Instructions:


If the published misfire diagnostic does not isolate the cause, perform the following suggestions as necessary:




1.

Perform a fuel injector balance test for all 8 cylinders. If a fuel injector concern exists, it is possible to misfuel an entire bank of the engine, causing multiple cylinders on the same bank to misfire even though the root cause is a single fuel injector.





2.

Inspect O2 sensor connections on the misfiring bank for corrosion or water intrusion. If water intrusion is found on the right bank, it may be due to the AC Evaporator Condensation dripping onto the O2 sensor harness. If this condition is found, reposition and shield the harness to prevent a repeat concern and repair the connections.





3.

Check for excessive exhaust backpressure using the restricted exhaust diagnosis from SI.





4.

Swap the Position 1 O2 sensors side to side to see if the misfires move to the other bank of the engine. If so, replace the O2 sensor.






And get you arm/hand in there get a little bloody and change out the 8th plug. do it when its cold and wrap your hand around the manifold. its ****ty but im sure the intermittent misfire on 8 is more likely a plug.

[Grounded]

Im gonna say to replace the fuel pressure regulator to fix the fuel pressure falling off.
pinch of the return line to see what the pressure does
it would help if you have a tool like the techII that would let you do injector balance

[TNTramair]

i would run a compression test before you throw anything else at it. and if you havent replaced the 8th plug yet...do that while you have it out.
i also think you may have a broken valve spring.

[PAFirefighter11]

Thanks guys. Tomorrow night if I have time I may pull the driver side valve cover to see what is going on and run a compression check if time allows.

Also, re: FPR. I'm hearing mixed reports. Some people are telling me the FPR is on the rail (Including GM Parts), others are saying it's in the tank and the piece on the rail is just a dampner for the pass. side rail to keep pressure the same?

[PAFirefighter11]

So if you're just reading this, #5 and #7 are the misfiring cylinders.

I purchased a compression tester today:
http://pafirefighter11.smugmug.com/photos/i-nG5D8Bc/0/XL/i-nG5D8Bc-XL.jpg

Only had time to do 4 cylinders, but everything checked out fine:
http://pafirefighter11.smugmug.com/photos/i-hVqTDN4/1/XL/i-hVqTDN4-XL.jpg

And the plugs ... 1-3-5-7:
http://pafirefighter11.smugmug.com/photos/i-2DFpjGR/0/XL/i-2DFpjGR-XL.jpg

[TNTramair]

thats a good start...hopefully the others are in the same condition.

[PAFirefighter11]

I don't know what Mode $06 test results are but here are mine:

Mode $06 report generated by Torque for Android
================================================

Vehicle VIN: Not present
Vehicle Manufacturer: Unknown
Vehicle Calibration ID: Not present

Unit and scaling information are not supplied with the data from the ECU for this type of vehicle. Consulting the manufacturers service book for this information is recommended.

Test report:
------------------
TID:$02 CID:$04
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$10
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$11
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$12
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$20
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$21
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$26
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$30
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$31
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$36
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$40
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$46
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$04 CID:$20
- High sensor Voltage for switch time calculation
Max: 32,766
Test result value: 32,770
FAIL
----
TID:$04 CID:$30
- High sensor Voltage for switch time calculation
Max: 32,766
Test result value: 32,770
FAIL
----
TID:$06 CID:$35
- Lean to Rich sensor switch time(calculated)
Max: 62
Test result value: 19
PASS
----
TID:$06 CID:$41
- Lean to Rich sensor switch time(calculated)
Max: 104
Test result value: 35
PASS
----
TID:$06 CID:$55
- Lean to Rich sensor switch time(calculated)
Max: 67
Test result value: 42
PASS
----
TID:$06 CID:$61
- Lean to Rich sensor switch time(calculated)
Max: 106
Test result value: 50
PASS
----
TID:$07 CID:$0c
- Minimum sensor Voltage for test cycle(calculated)
Max: 0
Test result value: 65,491
FAIL
----
TID:$07 CID:$0d
- Minimum sensor Voltage for test cycle(calculated)
Max: 1
Test result value: 65,491
FAIL
----
TID:$02 CID:$04
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$10
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$11
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$12
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$20
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$21
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$26
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$30
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$31
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$36
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$40
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$02 CID:$46
- Lean to Rich sensor threshold voltage(constant)
Test incomplete or dependant test failed
--
TID:$04 CID:$20
- High sensor Voltage for switch time calculation
Max: 32,766
Test result value: 32,770
FAIL
----
TID:$04 CID:$30
- High sensor Voltage for switch time calculation
Max: 32,766
Test result value: 32,770
FAIL
----
TID:$06 CID:$35
- Lean to Rich sensor switch time(calculated)
Max: 62
Test result value: 19
PASS
----
TID:$06 CID:$41
- Lean to Rich sensor switch time(calculated)
Max: 104
Test result value: 35
PASS
----
TID:$06 CID:$55
- Lean to Rich sensor switch time(calculated)
Max: 67
Test result value: 42
PASS
----
TID:$06 CID:$61
- Lean to Rich sensor switch time(calculated)
Max: 106
Test result value: 50
PASS
----
TID:$07 CID:$0c
- Minimum sensor Voltage for test cycle(calculated)
Max: 0
Test result value: 65,491
FAIL
----
TID:$07 CID:$0d
- Minimum sensor Voltage for test cycle(calculated)
Max: 1
Test result value: 65,491
FAIL
----

End of report.

[PhillyLS1]

I'd bet you money it's the Body Control Module

[PAFirefighter11]

I'd bet you money it's the Body Control Module

When the BCM starts to go bad it usually makes both windows slow or completely stop when going up or down. It also takes out the radio. Why are you thinking it's the BCM?

[FAST of WC]

Thanks guys. Tomorrow night if I have time I may pull the driver side valve cover to see what is going on and run a compression check if time allows.

Also, re: FPR. I'm hearing mixed reports. Some people are telling me the FPR is on the rail (Including GM Parts), others are saying it's in the tank and the piece on the rail is just a dampner for the pass. side rail to keep pressure the same?

Do a running compression like I suggested.

[elff]

One thing
Can you record a youtube video so we can hear the noise it makes.

I like the suggestion of the timing being off and the possibility of a bent valve or lash adjuster.
You also might have jumped a tooth on the timing chain

Just brainstorming

[PAFirefighter11]

Ignore the voltage. Gauge is off - verified with a multimeter:
November 2012: http://www.youtube.com/watch?v=_n_8yLhQNtU

And for comparison sake - back in April 2012 racing at Cecil:
http://www.youtube.com/watch?v=Gg6cifmbo5U

[TheAlchemist]

One thing
Can you record a youtube video so we can hear the noise it makes.

I like the suggestion of the timing being off and the possibility of a bent valve or lash adjuster.
You also might have jumped a tooth on the timing chain

Just brainstorming

There are no lash adjusters on these cars, and I've never heard of an ls1 jumping a tooth on a timing chain either. Timing is fine as well.

Ignore the voltage. Gauge is off - verified with a multimeter:
November 2012: http://www.youtube.com/watch?v=_n_8yLhQNtU

And for comparison sake - back in April 2012 racing at Cecil:
http://www.youtube.com/watch?v=Gg6cifmbo5U



PULL YOUR VALVE COVER RIGHT NOW. I can almost gaurantee a broken valvespring or bent pushrod. It's not that bad of a job to do. Also, have you verified the ground on the back on the driver's side cylinder head?

Lastly, get the car to someone with HPTuners to look at your tune. If you wanna drive up to Doylestown, I'll check it for you. My car sounded like that when I broken a valvespring. A broken valvespring will cause the neighboring cylidners to misfire because of the disturbance it causes around there. With HPtuners, I can actually scan each individual cylinder as it's running and you'll see a huge difference between each cylinder for misfires. So all the cylinders might be tripping the code, but you'll see one cylinder is like 320 misfires per cycyle, while the others are at like 40-50.

[PAFirefighter11]

There are no lash adjusters on these cars, and I've never heard of an ls1 jumping a tooth on a timing chain either. Timing is fine as well.





PULL YOUR VALVE COVER RIGHT NOW. I can almost gaurantee a broken valvespring or bent pushrod. It's not that bad of a job to do. Also, have you verified the ground on the back on the driver's side cylinder head?

Lastly, get the car to someone with HPTuners to look at your tune. If you wanna drive up to Doylestown, I'll check it for you. My car sounded like that when I broken a valvespring. A broken valvespring will cause the neighboring cylidners to misfire because of the disturbance it causes around there. With HPtuners, I can actually scan each individual cylinder as it's running and you'll see a huge difference between each cylinder for misfires. So all the cylinders might be tripping the code, but you'll see one cylinder is like 320 misfires per cycyle, while the others are at like 40-50.

That would ROCK! Thank you! I can get up there today if you're free? lol. I'm not too far from Buckingham Township. If not no worries. PM sent.

[elff]

Alchemist
Thanks for the clarification. Ive got half the engine of the TransAm :) and have lash adjusters. But i think our line of reasoning is the same for the problem.
I couldnt hear anything for what I was thinking of in the video. I was actually hoping you would put the camera in the engine bay to hear the engine better.

I have HPT as well but just had hip surgery so I cant do a test drive for a while. Im couch/bed ridden for a couple weeks. FAI fixed by FAO surgery for those interested.
Anywho
In the future, PAfighter11, I am right around the corner from your work. If you ever need to tune with HPT, you could borrow mine and just pay for the 2 credits to license your TA vs buying the whole suite

[PAFirefighter11]

PULL YOUR VALVE COVER RIGHT NOW. I can almost gaurantee a broken valvespring or bent pushrod. It's not that bad of a job to do. Also, have you verified the ground on the back on the driver's side cylinder head?

Lastly, get the car to someone with HPTuners to look at your tune. If you wanna drive up to Doylestown, I'll check it for you. My car sounded like that when I broken a valvespring. A broken valvespring will cause the neighboring cylidners to misfire because of the disturbance it causes around there. With HPtuners, I can actually scan each individual cylinder as it's running and you'll see a huge difference between each cylinder for misfires. So all the cylinders might be tripping the code, but you'll see one cylinder is like 320 misfires per cycyle, while the others are at like 40-50.

Thanks so much again for checking out the car! I'll get the driver side valve cover off tomorrow night after work hopefully.



In the future, PAfighter11, I am right around the corner from your work. If you ever need to tune with HPT, you could borrow mine and just pay for the 2 credits to license your TA vs buying the whole suite

Thanks much for the offer! I may need to tune out the rear o2's eventually as well.

[TheAlchemist]

Not a problem, I was happy to help. Unfortunately, I had another project already going on in the garage or else I would have helped you pull the cover here today.

For the record, he's got misfires only on cylinders 5 and 7, which to me sounded like he has either a broken valve spring or a bent pushrod or valve. Pulling the valve cover will tell a lot.

[PAFirefighter11]

I'll be pulling the valve cover tonight.

[PAFirefighter11]

Okay, photos of the valve springs:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-g2zvPxF/0/XL/IMAG0156-XL.jpg

7:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-JF2nzrN/0/XL/IMAG0158-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-RgkBnkT/0/XL/IMAG0163-XL.jpg

5:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-THtNQVR/0/XL/IMAG0164-XL.jpg

3:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-Gr3wj7j/0/XL/IMAG0165-XL.jpg

1:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-8cnZX4M/0/XL/IMAG0166-XL.jpg

Valve cover:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-NqKPV2r/0/XL/IMAG0167-XL.jpg

[Z/28]

Pull the push rods now batman. I have 8 stock pushrods and springs complete. Removed from my car @ 8k miles. If they are bent pm be on ls1tech. SMG267

[PAFirefighter11]

Pull the push rods now batman. I have 8 stock pushrods and springs complete. Removed from my car @ 8k miles. If they are bent pm be on ls1tech. SMG267

I have VERY limited garage time. It's 25 miles from my house as well. I only had time to pop the valve cover off, check the springs, take photos, and put it back together. I'll see if I can get time to check the pushrods. I really do not think it is mechanical.

[SHOdude]

I have VERY limited garage time. It's 25 miles from my house as well. I only had time to pop the valve cover off, check the springs, take photos, and put it back together. I'll see if I can get time to check the pushrods. I really do not think it is mechanical.

Make sure you put the rockers in order from how you took then out

[PAFirefighter11]

Make sure you put the rockers in order from how you took then out

Yah I've pulled 'em on other cars before. I have masking tape and # 'em. Not even sure when I will have time for pulling them.

[Z/28]

At the minimum I would have at least pulled the 5 & 7 push rods to check them. If the car is not your DD you should be able to do this in your driveway. It should be way faster now you know what you are doing. Did you ever swap the injectors around and see if the problem follows it?

[PAFirefighter11]

At the minimum I would have at least pulled the 5 & 7 push rods to check them. If the car is not your DD you should be able to do this in your driveway. It should be way faster now you know what you are doing. Did you ever swap the injectors around and see if the problem follows it?

I don't have a driveway lol. Gated condo parking lot. No maintenance of vehicles allowed. It has been too damn cold lately to work outside. It's currently back to my DD as my Jeep trans is done, my '01 needs a head gasket (bought it that way).

I have swapped around the coils and injectors a couple times without the problem moving to new cylinders.

[PhillyLS1]

When the BCM starts to go bad it usually makes both windows slow or completely stop when going up or down. It also takes out the radio. Why are you thinking it's the BCM?

Incorrect. It'll make the whole car go haywire. If it just makes your windows and radio FUBAR then you're lucky. This is extremely prevalent on 99-00 cars.

If your valve spring was broken you'd drop a valve. But the noise it's making does sound like what a dropped valve makes.

This problem is electrical, not mechanical. I've been working on these cars since they came out. My camaro runs pretty well :rofl:

Pull the spark wire on each cylinder to see if it makes a difference.
If you unplug the MAF and nothing happened? Then there's part of the problem. The car should react to that.

It's one of a few things that are electrical. If it was mechanical, the problem wouldn't clear it's self up.

My X had a TA with the same issue. The wiring harness was bad at the MAF. It wasn't getting a clean reading, but it made the same noises.

[PAFirefighter11]

I agree, at this point I am not thinking it is mechanical. FWIW: This was plug #8. I just pulled it tonight. PITA to get to as I'm sure you know..
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-mCsQBLs/0/XL/IMAG0173-XL.jpg

[Antonio]

well now...........that's not supposed to be like that lol. Hmmm, I wonder if this was being caused by a fouled plug the entire time.... Or maybe just a clue to something more serious. You said that compression was good in that whole bank so don't think the rings are toast....

[PAFirefighter11]

well now...........that's not supposed to be like that lol. Hmmm, I wonder if this was being caused by a fouled plug the entire time.... Or maybe just a clue to something more serious. You said that compression was good in that whole bank so don't think the rings are toast....

That's the #8. It doesn't look to have been replaced within the past 100,000 miles. That's most likely why it looks the way it does. It's still misfiring though. That cylinder is not a problem cylinder in terms of the misfires most of the time.

[Antonio]

ah, that's right duh. wrong side lol. Reading > me

[PAFirefighter11]

UPDATE: SO, I think I may have found the issue, or a big part of it. I decided today to check things I have checked already, just in case I missed something, or see if anything changed. On my way home I stopped, unplugged the MAF, reset the codes on the PCM with my Torque app, and drove. WOW.... what a difference. CEL is not blinking, it's not even on anymore. I drove it 25 miles home. The car still has minor hesitation but no big misfire. Check out these screen shots:

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-cnMvCnt/1/O/screenshot.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-cWvXsWh/1/O/screenshot.jpg

I'll order up a new MAF and see if that fixes things completely!

[elff]

Have you tried Cleaning the MAF? Before buying a new one?
There is a special spray for that.
I have some at my house if you want to try that before buying a new one.
You could drive by over lunch

[PAFirefighter11]

Have you tried Cleaning the MAF? Before buying a new one?
There is a special spray for that.
I have some at my house if you want to try that before buying a new one.
You could drive by over lunch

I did try cleaning it with the CRC MAF cleaner, gray/silver? bottle. To be honest, the issues may have started not too long after that. I appreciate the offer, man!

[Antonio]

any updates?

[jpalamar]

any updates?

This.

[PAFirefighter11]

Nothing new. I'm at the point where I am driving a Ford now... '13 "Gotta Have It" Green... I'm going crazy...

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-VPg4KSK/0/XL/IMAG0210-XL.jpg

It's kind of nice driving a comfortable, reliable vehicle...

[BlueEyedSuicide4]

Honestly it could even be something as stupid as a gunked to **** PCV system or faulty injectors.

[AutobahnRacer]

I am misfiring too! :cool:

[PAFirefighter11]

I've basically given up on the '98 for the time being. Anyone who wants to come check it out is welcome... I'm at a loss. Going to do the head gaskets on the '01 and probably sell that one. Need to thin the heard. Purchased a house.

[Honduh]

Did you ever do a exhaust back pressure test?

[PAFirefighter11]

Negative.

[Steve-Oh]

Lol what a waste of space! Sell both those black turds and buy a Mustang already!

[AutobahnRacer]

Let me Answer this for him.


Lol what a waste of space! Sell both those black turds and buy a Mustang already!


Negative.

[Steve-Oh]

Let me Answer this for him.

I dunno man, he really liked that 2013 he was driving! Probably faster then his TA.

[AutobahnRacer]

I dunno man, he really liked that 2013 he was driving! Probably faster then his TA.

Not sure I'd want either lol. Sure both are fast, but build quality neither are fantastic.

As for the misfire, I am in the same damn boat. I have replaced just about every conceivable part that would cause a misfire and am not any closer to a solution.

[PAFirefighter11]

My Dad's 2013 Mustang V6 Auto:
RWHP: 260
1/4 mile: 13.9
MPG: 31 Highway

2013 5.0L Mustang GT - Manual:
RWHP: 363
1/4 mile: 12.7
MPG: 26 Highway

My '98 Trans Am - 6 speed:
RWHP: 320
1/4 mile: 12.7 (If the damn thing ran properly)
MPG: 29 Highway

I just want it back on the road! 13.1 MPG overall in my 5.9L ZJ is killing me. I drive 50+ miles round trip a day. I'm honestly about to buy a Civic VX, HX or CRX HF. FML....

[Steve-Oh]

My Dad's 2013 Mustang V6 Auto:
RWHP: 260
1/4 mile: 13.9
MPG: 31 Highway

2013 5.0L Mustang GT - Manual:
RWHP: 363
1/4 mile: 12.7
MPG: 26 Highway

My '98 Trans Am - 6 speed:
RWHP: 320
1/4 mile: 12.7 (If the damn thing ran properly)
MPG: 29 Highway

I just want it back on the road! 13.1 MPG overall in my 5.9L ZJ is killing me. I drive 50+ miles round trip a day. I'm honestly about to buy a Civic VX, HX or CRX HF. FML....


Don't worry man, we'll get you fixed up! Let me know about Sunday.


Sent from Space

[PAFirefighter11]

Don't worry man, we'll get you fixed up! Let me know about Sunday.


Sent from Space

Man I hope so. I figure if anyone can fix it up it'd be you, Phil and Chris! BTW: Forgot you had a TST account haha. You going to post Cobra photos once it's on the road?

[Steve-Oh]

Man I hope so. I figure if anyone can fix it up it'd be you, Phil and Chris! BTW: Forgot you had a TST account haha. You going to post Cobra photos once it's on the road?

We'll def try our best! Forgot? lol I just signed up. I will eventually once it's finished. Just looks like a disheveled mess right now. http://i272.photobucket.com/albums/jj179/whereamioo7/random/f98143c4-201d-47c2-9a21-21af88e87a1b_zpsd8944af6.jpg

[AutobahnRacer]

I have three things left to do and not sure if anyone else said it because I am too lazy to go back and read if anyone else suggested it to you. Clean EGR and EGR ports, check injectors (myself) and check coil.

[PAFirefighter11]

We'll def try our best! Forgot? lol I just signed up. I will eventually once it's finished. Just looks like a disheveled mess right now. http://i272.photobucket.com/albums/jj179/whereamioo7/random/f98143c4-201d-47c2-9a21-21af88e87a1b_zpsd8944af6.jpg

Ooooh, snap.. that would be why hahaha... Word, looks like a mess, but a lot of power in that mess!



I have three things left to do and not sure if anyone else said it because I am too lazy to go back and read if anyone else suggested it to you. Clean EGR and EGR ports, check injectors (myself) and check coil.

I added a brand new EGR valve and some lines, as well as in-line filters for oil trappage. Nothing changed. Injectors are all fine. Coils are all fine.

[AutobahnRacer]

Ooooh, snap.. that would be why hahaha... Word, looks like a mess, but a lot of power in that mess!





I added a brand new EGR valve and some lines, as well as in-line filters for oil trappage. Nothing changed. Injectors are all fine. Coils are all fine.

I mean actual ports. My car has these, which are notorious for clogging.

http://rotordesign.com/accord/egr/P4270273_1.JPG

[inteva6184]

Mention of cobra steve chris and phil all in one thread wow its like the days of old. Chris and Phil are crazy buggers im sure they will figure it out or atleast have some crazy engine to replace it with haha

[Steve-Oh]

I mean actual ports. My car has these, which are notorious for clogging.

Interesting. We can def check this out Rick.



Mention of cobra steve chris and phil all in one thread wow its like the days of old. Chris and Phil are crazy buggers im sure they will figure it out or atleast have some crazy engine to replace it with haha

I know really?! We've all come out of the woodwork.

[PAFirefighter11]

Someone else who knows Phil, Chris and Cobra Steve? Impossibru! lol.

Updates...

Brought it to a buddy on Saturday. He is a master tech. Anyway, we used his MAF (He has a '98 TA as well, and a 3rd Gen) and it didn't change how the car runs. So he checked fuel pressure on his '98 TA is at 60 psi while running, drops to 50 when turned off, and stays there for hours upon hours. Mine is at 50 psi, then drops immediately to 0 when I turn off the car.

Today we tested the fuel pump draw and flow. Amps are around 7.5, which is just about where his '98 is (7.7). Also, volume of fuel is a bit more than his is flowing, so the fuel pump isn't the main issue. Changed the fuel filter, no change in drive-ability.

Checked vacuum. -15 or so at idle, and bouncing all over the place. Goes up to around 15-20 when on the gas, but again it's bouncing and not consistent. Per his tech book it's stating this could be a burnt valve, broken valve spring, etc. We're going to rip apart the top end this week.

[inteva6184]

Not only do I know all of them but I drive an import so it doesnt really make sense at all haha. Anyway good luck.

[Steve-Oh]

http://i272.photobucket.com/albums/jj179/whereamioo7/random/469C4044-6DD8-4E9F-94C1-E34366804F83-16531-000003B49DBA657E_zpscd21e392.jpg


Sent from Space

[Honduh]

i think i remember you saying you put a xpipe on? does that delete the cats?

[PAFirefighter11]

PROBLEM FOUND! Check the photos for the work done today... All are cell photos so the quality sucks:

Went to do a compression check:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-54nPSt3/0/XL/IMAG0383-XL.jpg

Then decided to pull the valve covers - passenger side:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-S9CrqkR/0/XL/IMAG0384-XL.jpg

A little closer:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-P5c9bVQ/0/XL/IMAG0388-XL.jpg

Time to rip the top end apart:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-chGJrTP/0/XL/IMAG0390-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-3BmwmWL/0/XL/IMAG0395-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-JxVLnr3/0/XL/IMAG0397-XL.jpg

Steve has his old LS1 with 55k miles on it (He has his LS6 now) so we're using his heads, springs, rockers, etc:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-4GvXqrt/0/XL/IMAG0391-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-tGtWjH9/0/XL/IMAG0392-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-VRJcGGg/0/XL/IMAG0393-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-s3MxzTB/0/XL/IMAG0394-XL.jpg

We're hoping to have the heads and everything swapped over by Saturday or Sunday at the latest. We ordered all the gaskets needed from GM today. Should be here tomorrow or Saturday. I can't wait to get this thing back on the road!

[TheAlchemist]

It's weird that a broken valve spring on #8 would lead to misfires on #5 and #7, but stranger things have happened. When you had the car at my house, I swore it sounded like a broken valve spring, and the scan lead me to beleive that it was on the driver's side, which is why I was surprised when you said the springs were fine. I had a broken valve spring a few years ago, and it registered as a misfire on that cylinder.

Well, at least you found it. I was going to tell you to be careful swapping a valvespring on the back cylinders because it's easy to screw up things back there, then it becomes a mess to fix.

[PAFirefighter11]

I agree, very odd. I appreciate the help as well!

Just throwing this out there... Does this look like a cracked rocker?

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-kM3RRBK/0/XL/Rocker-Close-XL.png

[elff]

compared to the one to the left it does

[Foolinaround]

Does look like a cracked rocker.

depending on the firing order it makes sense for the misfire.

[Steve-Oh]

Stupid LS motors lol, should of bought a Ford so you could of been down and out for two years like me! Seriously though man that's pretty crazy in there. Let me know what you're doing tomorrow man (Saturday)


Sent from Space

[PAFirefighter11]

Stupid LS motors lol, should of bought a Ford so you could of been down and out for two years like me! Seriously though man that's pretty crazy in there. Let me know what you're doing tomorrow man (Saturday)


Sent from Space

Hahahah, I'd rather have what you have in the Cobra now.. you should start a Members Journal if you haven't already? Throw in photos from when it was a lowly 5 slow to now!

I'm heading to "Trans Am Steve's" in West Chester. That's where my car is. We should hopefully have it all back together today. If you want to stop by I'm sure you're more than welcome. I'll hit you up with the address.

[PAFirefighter11]

Good seeing you today Steve-Oh. Thanks for checking on the progress. Seems like yours will be up soon too!

For those wondering: The rocker is not cracked. Strange optical illusion I guess. More progress today. Heads are off, everything is cleaned, getting ready to put the new heads on... Photos from today:

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-PjDSMwx/0/XL/IMAG0405-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-hFX7jBj/0/XL/IMAG0407-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-c3xQpMk/0/XL/IMAG0408-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-jnZ3H8j/0/XL/IMAG0410-XL.jpg

Oh haiii... Found 2 of these - of course we didn't verify which cylinder(s) they were from:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-vtsLjZP/0/XL/IMAG0412-XL.jpg

Looks like aftermarket springs, retainers... Possibly a head off of a newer Trans Am, Corvette, etc.?
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-GRLBNDv/0/XL/IMAG0413-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-nXMStrB/0/XL/IMAG0414-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-QLSjfTV/0/XL/IMAG0415-XL.jpg

Heads are going back on tomorrow or during the week (depending on family plans).

[PAFirefighter11]

And a couple non-cell phone shots with my Nikon D2x and Tamron 17-55 f/2.8:

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-r8rsHsb/0/XL/BCM_7828-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-bszQJQ3/0/XL/BCM_7825-XL.jpg

[TheAlchemist]

Both heads are 97/98 specific as they are perimeter bolt heads. FYI, if you're swapping to newer heads, you're going to need center bolt valve covers as well and I think the coils mounted to a bracket which then bolts to the valve cover in the 99+ heads. I think the 98s had the coils mounted directly to the valve cover.

[PAFirefighter11]

Both heads are 97/98 specific as they are perimeter bolt heads. FYI, if you're swapping to newer heads, you're going to need center bolt valve covers as well and I think the coils mounted to a bracket which then bolts to the valve cover in the 99+ heads. I think the 98s had the coils mounted directly to the valve cover.

Interesting. Thanks! I'm trying to find out why they did this with the aftermarket springs and retainers on one side.

[PAFirefighter11]

Let me also add. Valve float! It was to the point where the pistons have a slight gouge in 'em from the valves, but no other damage.

[PAFirefighter11]

Some progress last night:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-FvDxXJg/0/XL/IMAG0424-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-XssPzDJ/0/XL/IMAG0425-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-d7LT6z7/0/XL/IMAG0426-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-SXXbP2j/0/XL/IMAG0427-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-pv3V6HC/0/XL/IMAG0430-XL.jpg

[PAFirefighter11]

SHE RUNS!!

Video here:
http://www.youtube.com/watch?v=MfY7E8NGv10


Some more progress (cell phone) shots from yesterday:

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-9JMkDs5/0/XL/IMAG0433-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-4KWf72J/0/XL/IMAG0435-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-rzMZbcF/0/XL/IMAG0436-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-WWddcvk/0/XL/IMAG0437-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-93XDhJv/0/XL/IMAG0438-XL.jpg

Bolting the exhaust back together:
http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-NWKP4kN/0/XL/IMAG0440-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-kjBLXvz/0/XL/IMAG0441-XL.jpg

http://pafirefighter11.smugmug.com/Automotive/98-Trans-Am-Misfire/i-kDcwCPk/0/XL/IMAG0442-XL.jpg

We still need to add some coolant and a coolant temp. sensor.

[elff]

That seems to be a problem for high hp GM engines.
I installed stiffer springs and had to clearance the head on mine.

[PAFirefighter11]

Hmm. Strange GM gremlins are fun.

Video from yesterday of intake & engine area, and exhaust (Burning up some oil! No longer smokes though):
http://www.youtube.com/watch?v=PXdatfP3cEY

[Antonio]

great to hear it back to life again. Is there a squeaky/chirpy belt tensioner or idler pulley in the video. I have the same on my car and it's been driving me nuts. I gotta pinpoint which one it is. Before you have everything completely buttoned up might be easier to fix it.

[PAFirefighter11]

great to hear it back to life again. Is there a squeaky/chirpy belt tensioner or idler pulley in the video. I have the same on my car and it's been driving me nuts. I gotta pinpoint which one it is. Before you have everything completely buttoned up might be easier to fix it.

Thank you! There is! It's gone though. We replaced it yesterday. It was the lower AC tensioner pulley, belt etc. It's so quiet now it's weird....

[Steve-Oh]

Finally!


Sent from Space

[PAFirefighter11]

Glad to see your Cobra up and running now too! Get a Member Journal started !!

[Steve-Oh]

Ehhh these guys don't wanna see a 19 year old mustang lol


Sent from Space

[PAFirefighter11]

Yes, but it's got a huge motor and it's a Cobra.. so do IT! What the hell else ya doin'?! haha..