I have an 02 wrx. Mods- full exhaust, headers uppipe, invidia v3 divorced waste gate down pipe, No cats, VF34, STI pinks, walbro 255, perrin fuel rails, all silicon intake pipes, utec with a stage 4 base map.
I had just recently installed the perrin rails. After that the car has had misfire faults on all cylinders. Not a severe misfire, no flashing check engine light. It only misfires at idle when cold I think. When you chop the throttle real quick its has a slow rev response. The car has never been tuned its just running turboxs stg 4 base map. And i know its a big part of its ****ty running but it didn't run this bad untill i installed the rails. Is the fuel flow increased that much that it would make it do that? I've checked the car over thoroughly nothing went wrong with the rail install. I've had the car apart quite a few times with no problem. What i really want to know is this just a tunning problem or something else. I'm taking the car to be tuned in a couple weeks. i don't want them to put it on the dyno and find a problem with the car. Any help anyone could give me would be excellent. Thanks

 

sounds like tuning, no way you'd have a misfire on all 4 unless it was a fuel thing.

 

How many miles on the car? Anywhere between 60,000-70,000. I have misfire on my cyl 1-4 also. I talked to a guy that is very good with subaru and he said that they had a recall on the 02 wrx ecu cause it was having problems. To late now though since your at stage 4. I am also at stage 4, but my tune was done with one of the best in IL so I know its not the tuner. I am replacing my ecu with a 02 with a lot less miles I was told that this should cure the problem. I will let you know in about a week if this helped.

 

i am now having my car fixed for the same scenario. in my situation i had a cracked head and bent valves. just my .2

 

Did the car run fine when you had a cracked head and a bent valve?

 

no, it actually would not run at idle. it always hasd hesitation though

 

vaccume leak

 

aftermarket flywheel too light?

 

thats a good one too