So my 2002 wrx has not been 100% for a while and I've exhausted all of my ideas on diagnosing it and gotten nowhere. I have 2 issues however minimal they still bother me and keep me from fully enjoying my car. Problem number one is probably a boost leak and I'll do another boost leak test this weekend but last time I didn't find anything. The problem is that when I go into boost in 4th or 5th gear my boost fluctuates wildly. It goes up it goes down it goes up and down pedal held firmly, doesn't need to be floored to get these results. I don't notice it fluctuating in other gears only in 4th and 5th. After getting nowhere with a boost leak test I decided to order a new boost pill and all that jazz. No change. Not sure how to move forward on that, anyway that's the lesser of my worries. The more annoying issue is my accelerator pedal has a slight hesitation most of the time. It isn't always there but most of the time it is, it makes rev matching really difficult and unpredictable and makes going from a stop annoying. I had trouble with my iacv in the past so I figured that might be a factor so I cleaned that up. No change. I got a new throttle position sensor against my brothers advice (because it wasn't oem) and that didn't help. I got a used throttle body with all the sensors from a nice fella on the forum here and at first I thought that might have fixed it but it didnt. It may have helped with another issue that I've been having though which is lately when I've been starting it, doesn't do this on cold starts, when I start it the rpms drop way low for a second and it almost seems like it's going to stall out but then it doesn't and it's fine. Hopefully someone has had similar experiences and can shed some light for me. The only thing I can think of at this point is something is fudged with the wiring but I don't know squat about wiring or how to check for bad wiring. Help this sad little buddy out. Edit* types wrong word
spt short ram intake, perrin turbo inlet, walbro 255 fuel pump, sti "pink" injectors, turboxs up pipe, Cobb down pipe,Nvidia catback, exedy racing clutch/lightweight flywheel, Cobb lightweight crank pulley, uhh mishinono y pipe
E tuned by my brother. Basically had all these mods on my previous bugeye and ran same tune and didn't have these issues. That's why I think possibly wiring issue because I think the previous owner of this bugeye might have hosed it
1st gut feeling is a boost/vacuum leak. Would cause a stumble on startups and would give you your boost variations. Have you logged your boost to see if it is over boosting? If it over boosts, it will drop down and work its way back up. The reason you will see that in 4th/5th gear is that you will have a much higher load on the motor in those gears and you have a longer time to stay in the throttle. Russ
So I've tried adjusting the wastegate. Before I was peaking at 18/20 then I shortened the arm 1 turn and it was peaking at 17. I extended the arm 1 turn past where it started and it went up to 22. After I put in a new boost pill and line it now fluctuates in 2nd and 3rd
Someone kindly explain how the wastegate actuator works and what lengthening/shortening the arm does?
Did they boost leak test and apparently my clamp on the y pipe to turbo was crooked and letting air pass. Got it fixed and now I'm ready to rip.
Welp on first drive it didn't fix the issue but I had the wastegate actuator set up too high. Boost peaked at 23. Brought it in 2 full spins now I'm getting 18. I think that's where I want it, to be safe, but I think if I go back one turn I would be getting 20-21. Question: How does changing the wastegate actuator affect the tune or vice versa? For example if my tune is set up a certain way to hit a certain amount of boost would having the actuator set too high cause weird things to happen? ie. My boost fluctuations.
Bypassed my boost control solenoid as per my brothers advice and had no boost fluctuations. This means it's most likely a bad solenoid, which is funny because I have 3 that all do the same thing.
Fluctuate boost...wildly. Some might be worse than others. Basically have to just run it bypassed getting 8-9 pounds of boost until I can get #iantuned (lol) for my 3 port. @FlatBlackIan come back to the light side.
This is how he put it. "The wastegate is preset to 7.5 lbs, and the ECU dumps pressure with the solenoid to bring it up to the factory 14." Since I am skipping the solenoid I only get that preset 7.5 lbs. Which according to my accessport is 8.6 lol. This still feels better than it fluctuating all over.
