About tuning.
Yes, with almost any type of engine mod, you need some type of tuning. If you just go into google and search for what you want to know, you will find your answers multiple times faster than posting through here. Not to mention you will find other valuable information that you can later reference.
02/03 models you can get way without a tune when installing a downpipe, up-pipe, CBE and a few other things. However, to reach full potential, a tune would be needed
Technical Know-It-All
Joined: Oct 2003
Posts: 2,123
From: Sterling, VA
Car Info: '02 WRX + '15 WRX
'02-'03s don't have the close loop -> open loop fueling transition delay that causes +04 WRXs and +05 STIs to need to be tuned with a downpipe.
For later models, removing the cat drops the post-turbo exhaust restriction significantly. This increases the pressure drop across the turbo, which spools it quicker. The result is two-fold: first, because it's easier to spool the turbo, the turbo spools sooner (lower RPM). This means the stock delay the ECU uses before it switches to open loop fueling is now too large, which means the car will continue to stay in closed loop (14.7 AFR) well into boost, which can cause damage. The second result is that because the turbo spools easier, in order to maintain target boost you must open the wastegate more, which means you need to change your wastegate duty cycle tables to prevent overboosting.
For later models, removing the cat drops the post-turbo exhaust restriction significantly. This increases the pressure drop across the turbo, which spools it quicker. The result is two-fold: first, because it's easier to spool the turbo, the turbo spools sooner (lower RPM). This means the stock delay the ECU uses before it switches to open loop fueling is now too large, which means the car will continue to stay in closed loop (14.7 AFR) well into boost, which can cause damage. The second result is that because the turbo spools easier, in order to maintain target boost you must open the wastegate more, which means you need to change your wastegate duty cycle tables to prevent overboosting.
Last edited by Brfatal; May 15, 2013 at 08:34 PM.
'02-'03s don't have the close loop -> open loop fueling transition delay that causes +04 WRXs and +05 STIs to need to be tuned with a downpipe.
For later models, removing the cat drops the post-turbo exhaust restriction significantly. This increases the pressure drop across the turbo, which spools it quicker. The result is two-fold: first, because it's easier to spool the turbo, the turbo spools sooner (lower RPM). This means the stock delay the ECU uses before it switches to open loop fueling is now too large, which means the car will continue to stay in closed loop (14.7 AFR) well into boost, which can cause damage. The second result is that because the turbo spools easier, in order to maintain target boost you must open the wastegate more, which means you need to change your wastegate duty cycle tables to prevent overboosting.
For later models, removing the cat drops the post-turbo exhaust restriction significantly. This increases the pressure drop across the turbo, which spools it quicker. The result is two-fold: first, because it's easier to spool the turbo, the turbo spools sooner (lower RPM). This means the stock delay the ECU uses before it switches to open loop fueling is now too large, which means the car will continue to stay in closed loop (14.7 AFR) well into boost, which can cause damage. The second result is that because the turbo spools easier, in order to maintain target boost you must open the wastegate more, which means you need to change your wastegate duty cycle tables to prevent overboosting.
Technical Know-It-All
Joined: Oct 2003
Posts: 2,123
From: Sterling, VA
Car Info: '02 WRX + '15 WRX
You aren't required to get a tune, assuming you're running either the '03 stock ECU or a '04 STI ECU, you probably should anyways to get the most out of the setup and would be money well spent. You're very confusing btw, '02 WRX mentioned in your profile, though it's an '03 with an '04 swap.
Last edited by Brfatal; May 16, 2013 at 07:15 AM.
banned
Joined: Dec 2009
Posts: 620
From: Rocklin
Car Info: In front of high schools impressing teenagers.
Registered User
Joined: Sep 2012
Posts: 18
Buy a cheapo vag com cable and change the bit rate to 4800 and use romraider to watch your Iam and make sure it stays at 16. Also make sure you don't have a loose heat shield because you will be chasing knock for weeks until it finally hits you. Ask me how I know lol.
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