...and if yes what are the results?
I have a full decated WRX03 (Scoobysport except the back box that is STI)and have offered a PPP ECU so I wonder worth the money?
JIM

 

I was advised not to decat my 03MY WRX PPP by my local dealer.

Apparently it makes them a pig to drive round town and at slow speed

 

Why this?
The decat should add in spool up and driveability but will make the mixture leaner, if you run less than standard PPP boost (less than 1.2bar, say 1 - 1.1) as I am going to do you should have about the same Injector duty cycles and can't see where the problem is!
May be they want to prevent you from changing your exhaust.
JIM

 

I fully decatted my wrx01 ppp , but i also replaced the wastgate being scared of cracking the turbo. I also fitted a pop off and istalled an STI TMIC. The car now run for 40,000km without any single problem except for having burnt twice the O2 sensor ( I gave up replacing it since the car goes perfectly without it) . The car sometimes run slightly rich wich is not bad. Apart for the gain in power and torque (270bhp @ 5000rpm and 270 Lb/ft @3500 rpm..with 1.2/1.3 bar pressure) the car is perfectly drivable from 2000 to 7000 rpm, turbo lag is virtually inexistent from only 3000 rpm. I must say it now goes better than an STI.

 

That's interest mate as I am going to fit also an STI TMIC and limit the max boost at safety levels between 1.1-1.15 bar if I buy the Prodrive maped ECU!
Believe me it's really difficult to find over here good mappers for our cars thus the interest for the ECU.
JIM

 

Jim when you decatted your MY03 did you not get a Remap carried out.

If you did not, how did your car run with the full decat only, ie was there a huge difference in the pull of the car.

reason i am asking, i get my MY04 Decatted this week. i was not sure for a while about the full decat, as i had many mixed stories about needing a map/not needing a Remap, so i have just decided **** it and go for it.

cheers Jim

Paul

 

No remap at all Paul and no problems with full decat.
Injector duty cycles where about 102-103% with the Scoobysport back box and less than 100% currently with the STI back box (change due to noise levels, I am getting old mate) but in every case the mixture is very reach.
I had about 230+ ps on the wheels measured with Delta Dash with full Scoobysport decat and 220+ now with the STI muffler and Scoobysport rest, always with 100RON fuel.
I have much better spool up low down (even better from the PPP cars until 3400rpms!) and increased driveability but also some boost oscillation around 3000 rpms, not extreme and not worrying thus I am going to fit a flow control valve in place of restrictor oriffice to cure it when I fit the STI intercooler.
The only negative is the exhaust gas smell that is unacceptable when parking on closed areas.
Hope the above help you decide!
JIM

 

Jim,

I always advice to use a 1.1 mm restrictor in stead of the 1.0 mm restictor in the MY03/04 WRX after fitting a decat exhaust. This cures all the overboost and oscillation of boost.

I´ve heard of one guy here who replaces the downpipe for a decat in a MY04 PPP car and he had fuel cuts. I think changing the restrictor in that situation also should cure the problem.

Mark.

 

Thanks Mark, I already have a Festo flow control valve that will replace the small restrictor but as I can't find the air hoses between turbo exit > T connector > wastegate in Subaru (they have never ordered such parts for new age cars and aren't the same size with old shape Imprezas, 4mm instead of 3,5mm inside diameter on olders) I am waiting until my STI intercooler comes from USA thus I adjust once and for all the boost.
Actually the oscillation is negligible only from 14,3 psi to 13,8 but wonder if the Prodrive ECU coul cope with my exhaust and STI I/C, with the valve I can adjust the pressure whenever I want to say 1,1bar in order to avoid high IDC and lean mixture.
JIM

 

If you adjust the flow control valve in a position that doesn't give too much overboost, you should be fine! The boostcontrol is very nice in the MY03/04 ECU and should be able to control the boost to the target PPP settings. (1.3 bar overboost isn't a problem as long as you don't get oscillation)

You easily max out the injectors in a WRX. Nothing to worry about. If you can keep it below 1.0 bar @ 6000 RPM your mixture will be rich enough at max. injector duty. (I don't know how much boost the PPP is running at 6000 RPM though)

Mark.

 

thanks Jim for your spot on opinions. i am going ahead now anyway, will see what prevails.

cheers for the advice.

Paul

 

Even on STIs PPP the boost above 6000 rpms Mark is at or below 1 bar (actually on WRXS after 4800-4900 rpms drops gradualy to less than 1 bar at 6000rpms) but have seen PPP cars that have 105-108% IDC and work perfectly a year now without problems.
JIM