Phantom knock on my SR20!?

[iloveturbolag]

i experianced alot of phantom knock with my 1g dsm when i first bought it. but with much searching for a rattle and playing with the amount of torque on a brand new knock sensor i finally got it to go away. i also used my DSM link so it would not read knock below "xxxx" Rpm's and xx% TPS.

After driving the new car around (s14 w/ sr20det stock turbo stock boost, plenty of bolt-ons) every so often i get phantom knock below 3000 rpm. i know its not real because it only happens between 50%-75% throttle. it pulls my timing like crazy and i get full spool at about 1600rpm. my car sounds like im flying but feels like the hands of god are holding me back. its clearly igniting AFTER TDC. it happens some times when i get on it real quick to, it will spool real fast, be bogging down, then the phantom knock goes away, timing come back, all of a sudden the engine tone changes and im off. it sounds almost like it has Vtec its so bad.
im new to the SR20 scene and just was wondering if anyone else had similar problems.
im looking into getting some form of engine managment soon and hope that theres a feature on it to play with the knock sensor but i decided what i want to go with. possibly greddy E-manage ultimate? maybe AEM???
any help would be greatly appritiated cuz Im going crazy.
DAMN YOU YOU KNOCKING PHANTOM!

[iloveturbolag]

anyone? this can't be that unusual of an incident???

[Proven]

Id def. give one of the shops on here a call that deals with SR's like R/T Tuning, Import DPS, or even elitejdm.com who sells these engines. My ONLY guess would be the timing is thrown off (can happen in shipping if this is a newer swap) or ignition issues. Check your coils for consistant spark. Of course keep checking for something that may be loose in the engine bay. Ive heard of loose brackets causeing "knock"

[BlkWhtTSI]

possibly (this happened to me and now is gone) it might be the temperature since during winter the air is colder and more dense this is why turbo cars run better and pull harder in winter your actually seeing more air than what you think so you have to compensate richen your car up a little bit see if you see less knock. check your timing etc.

[Rotary Knight]

How did you know the timing changed, with a timing gun?

[Renegade_]

get a timing gun and check it

[iloveturbolag]

^^i "know" the timing changed just because of how the car is behaving. its classic symptoms of phantom knock (fake knock, fony balony knock, non-genuine knock, bs knock). the tone changes, spool is fast, and power is non existant.

i know its not real knock tho, because real knock wouldn't only happen at low RPM with partial throttle, and its pulling my timing past TDC. knock must be reading off the charts below 1500rpm which is rediculous! i've floored it when its happened in 3rd gear at about 1400rpm to check my beliefs and gotten full boost by 1600. i know the t25 spools fast but damn. i can feel it and hear it when it happens, its just like the opposite of vtec, less power with boost. its to the point where my car will not want to even accelerate, it will just kinda stay at the current RPM even at WOT. if i back off the throttle to about 20% it starts to pull harder again. CRAZY. if i ease up to about 3500rpm then get on it its fine, this only starts at low rpm and then continues throught the range.

again this is not the normal case. this only has happened a few times. when it does tho, it will happen intermitenly throught the drive and then the next time i drive it, it doesnt. i am going to get some sort of data logging software to conferm my hypothesis but i feel it will show exactly what i believe is happening.

[TurboTagTeam]

So what kind of tune/ecu are you running? Base timming should be 15degrees. then ramp up to 32 or so and fall off .75degrees per every pound of boost. At least thats how i tuned my sr. I dont want to imply that your wrong and it's not the timing, but have you checked for boost leaks also?

[iloveturbolag]

the car is running a factory ECU with factory boost. every so often i run 11psi which is the high setting on my greddy profec B, and i RARLY do this. boost leaks and poor timing settings would explain poor performance all the time, but this is very sporatic. most days the car is extremly fast and runs great, but a handful of times this has happened. i "KNOW" its phantom knock as it has every symptom, im not looking for other possible issues (no offence i do greatly appritiate all the feedback and help) i just would like to know if anyone had a simmilar problem with this and had some sort of solution. with my DSM i got a new knock sensor and hand tighted it as far as it would go, then another 90 degrees with a wrench. this seemed to stop it all together, plus i tuned it out a bit with DSMlink.
any suggestions?

[BlkWhtTSI]

if your so certain its the timing why dont you just find a timing gun and check it? but would a timing issue be sporatic and random like you say? i would think it would happen everytime.

[iloveturbolag]

Originally Posted by BlkWhtTSI

if your so certain its the timing why dont you just find a timing gun and check it? but would a timing issue be sporatic and random like you say? i would think it would happen everytime.

when a car reads knock, it can do one of 2 things to try to suppress it. it can either run richer (not likely), or pull timing. most all cars with digital ignition do this. if there is something rattling on the motor, a knock sensor reading wrong, or something else unknown, the ecu can read high counts of knock, abnormally high.

if the ecu is reading these insane high counts of fake knock (phantom knock) it will pull timing to the point that the car is making almost no power.

your DSM does the same thing when it reads knock, i believe its anything over 3 counts starts to pull timing.

[BlkWhtTSI]

yeah i know, i was knocking once like last week i riched the car up a little and its fine

[I<3myS14]

Sounds like a timing issue to me....stop talking about knock and do this!

Warm car up to operating temperature at around 1500rpm, shut off once hot, pull throttle position sensor, restart, shine timing light on crank pulley, read timing.

Timing pulley is marked like this

|..|..|..|..|..|
5..0..5.10.15.20

At idle, you should see 15.

Don't use the loop on the coil pack harness to check it, get a spark plug wire, cut the end that would go to a distributor and use that. My S15 motor was a pain to get to timing mode so you may need to try the above method multiple times to get it to see timing mode. It all depends on the rpm and your idle control. You can tell once it goes to timing mode.

If it's off adjust the crank angle sensor either up or down while shining the light on the crank. If the timing is good, I agree with tag team...do a boost leakdown test. You should have checked the timing of the motor before you cranked up your boost.

[Vince@R/TTuning]

Nissan Knock sensors have the life of expectancy of a gold fish....some of them last a long time but most of them die sooner then they should. It doesn't have the be (phantom) Knock...Nissan ecus need to see a slight voltage to know the knock sensor is working and if that voltage drops off...it will also pull timing as a safety measure. So do this...take off the Knock sensor, clean where it attaches to the block(thats its only ground) and then re tighten it and see if it is better.

If it doesn't then replace the knock sensor anyway as a preventive maintenance for when you do get a standalone....cough.. cough... POWER FC cough.. cough..

knock sensors on Nissan's dont work the same as Mitsu's...they have knock threshold which is normal engine noise and anything on top of that is knock...

so they are always reading some engine noise and creating voltage

[iloveturbolag]

haha thanks vince, ill give that try. im definatly looking into that power FC too.
and thanks shaun, ill get my hands on a timing light and give it a go, and a boost leak test can't hurt either.