downpipe on my sti - TriStateTuners.com :: Home of Tristate Auto Enthusiast

rocco · 10-04-2007, 07:50 PM

i have a 2004 sti and i bought a perrin dp from my buddie. whats the deal? i read the install in the diy thread. is it any diffent than the wrx and it has no cat so what should i do? do i need to have my computer adjusted and will a check engine light come on?
also i have a cat back do i need to have the computer adjusted for that as well?

**TROLL** · 10-04-2007, 07:53 PM

you dont need to be retuned but you might have boost creep issues. its a mechanical problem involving the wastegate in the stock turbo and the only way to fix it is to take the turbo off and have it ported. (or ewg or aftermarket turbo).
the install is the same as on a wrx though.

rocco · 10-05-2007, 10:27 PM

so should i maybe look into a new turbo? will i need to replace my top mount for a fmic? can i borrow some loot?

rocco · 10-05-2007, 10:30 PM

ive had this down pipe for awhile now i want to install it. i also have an egt gauge so i need to buy a pod. i have a new boost gauge too. can i hook that thing up to the old boost gauge?

**TROLL** · 10-05-2007, 10:39 PM

depending on the gauge you'll probably have to install all new components for it but thats probably a good idea anyway.

you can just install your downpipe but just watch your boost gauge to make sure that in higher gears and higher rpms your boost doesnt start creeping up higher than it should. if so then get off the throttle, and then think about porting your turbo to fix the boost creep problem.

Honest_Bob · 10-06-2007, 12:22 AM

Quote:

Originally Posted by TROLL

you dont need to be retuned but you might have boost creep issues.

uhh he definitely wants to be running some sort of stage 2 map.

I am assuming you are swapping the stock downpipe for the new perrin one? Yes you will get a check engine light (Code P0420 to be exact). Your going to need some sort of engine management to be running safely with the downpipe. Most have the ability to get rid of the check engine light.

**TROLL** · 10-06-2007, 12:26 AM

engine management wont fix boost creep. it may lower the wgdc's so its not any worse than it has to be but boost creep is completely mechanical and is not a result of tuning. he'll definitely benefit performance wise from a stage two map but its not required.
and i forgot about the cel, thanks for bringing that up.

Honest_Bob · 10-06-2007, 12:35 AM

Quote:

Originally Posted by TROLL

engine management wont fix boost creep. it may lower the wgdc's so its not any worse than it has to be but boost creep is completely mechanical and is not a result of tuning. he'll definitely benefit performance wise from a stage two map but its not required.
and i forgot about the cel, thanks for bringing that up.

Its an 04. I'm pretty sure that has issues with the open loop/closed loop. 02/03 wrx's were fine but 04+ wrx are not safe to run long term with a stage 2 setup on the stock map. Unless STI's are different.

Buster · 10-06-2007, 02:07 AM

Quote:

Originally Posted by Honest_Bob

Its an 04. I'm pretty sure that has issues with the open loop/closed loop. 02/03 wrx's were fine but 04+ wrx are not safe to run long term with a stage 2 setup on the stock map. Unless STI's are different.

Thats not entirely true, that was ill maintained 04+ cars. Of course you car will explode if you don't monitor. I ran an untuned high boost stg 2 and was fine for 2 years. Also Bryan, the Ap has been said to correct boost creep when moving to their stg 2 map.

**TROLL** · 10-06-2007, 10:14 AM

engine management cannot fix boost creep... its a mechanical issue and would be 100% impossible and defy the laws of physics to be fixed with a tune!!!! its ok i'll keep saying it over and over and people will keep thinking it can be fixed by a tune because they dont understand what actually causes creep.

and i think the OL/CL issues were 04 WRX only, not affecting other model years or STis (except that 07 STi's have their own similar issues

)

S4toSTI · 10-06-2007, 10:27 AM

I have an 05 sti i have run a dp on a stock map for i think it was at least 5-6 months and i never had a problem and we know how easy i drive my car :smile: . Anyway point of the matter is some dp's are also more prone to creep than others. I never had a problem with my cobb or my perrin but i have seen people have problems on those. Boost creep is a very weird thing and as Bryan has said it can not be fix by a tune. The cobb stg 2 map alters waste gate duty cycle which may aid at preventing creep but will not fix it. Also the rest of the exhaust has alot to do with it. When i basically had an open dp i had horrible boost creep issue on the stage 2 map. Anyway to answer one of your other question no you don't need an after market turbo.

CHAOS · 10-06-2007, 10:27 AM

boost creep is actually a rare occurance from what ive seen...i wouldnt worry about it too much.... but when you get a DP is usually a good idea to get some sort of engine managment to get the most out of that modification

S4toSTI · 10-06-2007, 10:34 AM

Quote:

Originally Posted by CHAOS

boost creep is actually a rare occurance from what ive seen...i wouldnt worry about it too much.... but when you get a DP is usually a good idea to get some sort of engine managment to get the most out of that modification

To say its a rare occurrence is a pretty bold statement. And it is definitely something i would worry about right about. If you drive your car for a few hundred miles and it never happens, you should should be ok. Just watch your boost gauge and if it goes high get off the gas. I do agree that you need a tune to get the full benefit though.

CHAOS · 10-06-2007, 10:38 AM

the reason i say its rare is because ive never seen many actual occurances of it in my "travels" lol

**TROLL** · 10-06-2007, 10:38 AM

yup, so in closing... just go ahead and get the downpipe installed, but keep an eye on your boost gauge in higher gears at higher rpms where boost creep is more likely to happen. if the boost rises higher than what is safe then get off the throttle and reevaluate the situation then. if it doesnt rise, then fuggettaboutit.

rocco · 10-06-2007, 11:37 AM

ok so install the downpipe look into some type of computer upgrade. im guessing cobb stage1 or stage2? and if i have problems with boost i should have the stock turbo ported.

S4toSTI · 10-06-2007, 01:17 PM

Quote:

Originally Posted by rocco

ok so install the downpipe look into some type of computer upgrade. im guessing cobb stage1 or stage2? and if i have problems with boost i should have the stock turbo ported.

You got it and watch your boost.

DaveSTi · 10-06-2007, 02:28 PM

EM before DP, IMO. You're going to overboost on a stock fuel map. Your engine may not blow up, but c'mon. It's like not changing your oil every 5k. Sure, it'll last longer and your car will be "fine" but...

jons05sti · 10-06-2007, 04:03 PM

I have an 05 sti I put an hks downpipe on my car. Within 100 miles i got a cel for no cats and suffered from boost creep from 4th gear on. I bit the bullet and had the waste gate ported.

rocco · 10-07-2007, 12:04 AM

what do you mean em before dp , imo ? should i look into cobb for tuning or is there something else you would recomend? man one pipe can be such a pain in the ass

10-04-2007, 07:50 PM	#1
rocco Tri-State Post Whore Join Date: Feb 2006 Location: sj Member #1549 iTrader: (0)	downpipe on my sti i have a 2004 sti and i bought a perrin dp from my buddie. whats the deal? i read the install in the diy thread. is it any diffent than the wrx and it has no cat so what should i do? do i need to have my computer adjusted and will a check engine light come on? also i have a cat back do i need to have the computer adjusted for that as well?

10-06-2007, 02:28 PM	#18
DaveSTi Tri-State Post Whore Join Date: Mar 2006 Location: Charlotte Member #1591 iTrader: (0)	EM before DP, IMO. You're going to overboost on a stock fuel map. Your engine may not blow up, but c'mon. It's like not changing your oil every 5k. Sure, it'll last longer and your car will be "fine" but... __________________ Member Journals: To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. / To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. / To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. / To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. / To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures. / To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

10-05-2007, 10:27 PM	#3
rocco Tri-State Post Whore Join Date: Feb 2006 Location: sj Member #1549 iTrader: (0)	so should i maybe look into a new turbo? will i need to replace my top mount for a fmic? can i borrow some loot?

10-05-2007, 10:30 PM	#4
rocco Tri-State Post Whore Join Date: Feb 2006 Location: sj Member #1549 iTrader: (0)	ive had this down pipe for awhile now i want to install it. i also have an egt gauge so i need to buy a pod. i have a new boost gauge too. can i hook that thing up to the old boost gauge?

10-06-2007, 10:27 AM	#12
CHAOS TST Ruined My Life! Banned Join Date: Jun 2006 Member #2120 My Ride: 1984 Cadillac Brougham iTrader: (1)	boost creep is actually a rare occurance from what ive seen...i wouldnt worry about it too much.... but when you get a DP is usually a good idea to get some sort of engine managment to get the most out of that modification

10-06-2007, 10:38 AM	#14
CHAOS TST Ruined My Life! Banned Join Date: Jun 2006 Member #2120 My Ride: 1984 Cadillac Brougham iTrader: (1)	the reason i say its rare is because ive never seen many actual occurances of it in my "travels" lol

10-06-2007, 11:37 AM	#16
rocco Tri-State Post Whore Join Date: Feb 2006 Location: sj Member #1549 iTrader: (0)	ok so install the downpipe look into some type of computer upgrade. im guessing cobb stage1 or stage2? and if i have problems with boost i should have the stock turbo ported.

10-06-2007, 04:03 PM	#19
jons05sti Tri-State Aficionado Join Date: Jul 2005 Location: L-town Member #639 My Ride: 09 C300 2012 Nightster 1200 iTrader: (0)	I have an 05 sti I put an hks downpipe on my car. Within 100 miles i got a cel for no cats and suffered from boost creep from 4th gear on. I bit the bullet and had the waste gate ported.

10-07-2007, 12:04 AM	#20
rocco Tri-State Post Whore Join Date: Feb 2006 Location: sj Member #1549 iTrader: (0)	what do you mean em before dp , imo ? should i look into cobb for tuning or is there something else you would recomend? man one pipe can be such a pain in the ass