97 WRX Wagon in NZ running problems
 

Good Morning Scooby fans,

Wonder if someone can help me. These are the mods carried out so far:
Standard EJ20 Turbo from a Japanese import WRX Wagon.
TD05 Upgrade
STI RA ECU
Yellow injectors
STI MAF
Decat downpipe.
Boosting at 14psi no surges.

Since the upgrades the car was running sweet until one day I had some misfiring issues at 100kmh. As you put power on it would have a major hesitation then pull away. It also started idling 1500rpm at random times. So since then I have replaced the following with used parts. Maybe not wise when looking for a problem.

TPS was swapped out.
IACV Swapped and cleaned.
O2 sensor on downpipes changed (this stopped the hesitation)
MAF swapped out and changed.
ECU Swapped from an STI to and STI RA.

Since then I have had no more hesitations but now the car is idling up to 1100 at times and surging. It sometimes hesitates is hot then parked up for 30 mins and driven away it may do a few kangaroo jumps then all good again. It also feels like it has a dead band at about 2500rpm where it feels like it wants to hesitate but doesn't. All a bit odd really.

Any suggestions would be greatly appreciated guys.

You have an aggressive ecu for an sti in a wrx and your wondering why its not running correctly, engine is probably toast mate you have chucked a load of parts on it at ramdom without having it properly tuned.

Hello mate. I don't see how you came up with that solution? The WRX block and STI block are fairly similar are they not apart from different compression pistons and strengthened internals?

Surely putting STI components onto a WRX engine is going to make it run like an STI but may lead to more stress on the engine? I have not wound up the boost and it runs well. Seems like a smaller problem than a toasted engine?

Why would you need to tune and STI Ecu if you are running STI MAF, Injectors and ECU?

A standard STI does not have a decatted DP and you have not tuned your AFR's for this so this could be your problem.
So Jay is correct,you could be running lean and toasting your engine.
Do you have an AFR gauge fitted?

Also STI cams have different profiles to WRX cams.

What fuel are you using?

Very good point!
Do they even have 99ron in NZ?

Thanks guys. I am running BP 98 Ultimate over here. It seems to be running much richer than leaner looking at the tip of the exhaust. What would be the best way to get it tuned properly? Open source Link ecu or ecutek reflash of the ecu?

You can't OS or ecutek your car.
Have a look into getting ESL,the best option in my opinion.
As for BP petrol,we over here seem to have problems running that cr@p in our cars,I know it's 98 but it's sh1te.

Bp 98 on a un mapped sti jdm ecu and decated?? All fitted to a wrx engine?

I take it this is bad then? Apart from the cams being different and the heads being a slightly lower compression then changing the ECU and maf, injectors and turbo would it not run ok? Essentially changing the components to think it is running like an STI but not turning the boost up too much.