I have a 2002 wrx, and has been tuned for what i have in the car on 1st august. Car has been running fine. As of last night i was driving home along orrong road in 3rd gear and some dumbass was in the right lane doing 40, so i slowed down to 40 and gave up so went around, still in third gear, as i hit full boost (1.4/1.5bar) the car started jerking as if i was turning the fuel on and off. it also made some light popping noise.

I though perhaps that the cold air was making the car overboost as i shouldnt get 1.5bar of boost. This morning the same thing is happening. The car is not giving any CEL's. Only does it at WOT. If i slowly pull away and hit boost its fine (keeping it around 1 bar) anything above that, bam, the car jerks around a bit and the boost flicks up and down as it goes towards 1.4bar

What i have tried:
Replaced the fuel filter, and the fuel pump is basically brand new (walbro)
I sprayed carby cleaner around the engine bay near vac lines and saw no noise change/pressure change in the gauge for vacumn.

Can anyone suggest anything to try next? I have unplugged the maf and drove around and it was fine. I had literally just come out of the tunnel where i dumped the car through it (come on, who else doesnt) and the car was still running fine.

There does sound like a small air "flow" coming out from where the purge control valve is, next to the alternator. But i wouldnt think that would cause the issue?

Impreza GT GC8 jerky acceleration on WOT - YouTube thats what the car sounds like, its hard to record my own car. Its going to evo r next week if i cant solve but thought id ask incase anyone could recommend things?

Coilpacks? Spark Plugs (iridium ones, only done about 20 thous km)? intake pipe doesnt sound split, i do have one sitting here to install though.

Cheers Guys,
Josh

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2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe

Take it to who tuned it and get them to look at it. That looks like a gc cluster so not a bugeye


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race tape y pipe running .05 bar till spares turn up.

When was the tune done?
Who did it?

If it was done within the past week or two then I'd be directing questions at the tuner personally. No point playing guessing games imo.

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[I]trolololol[/I]

@munya, its a gc cluster as i didnt record my own car but thats what it is doing.
@trolley. Mao did it at evor on 1/8/2013. I am seeing him next week to see what he reckons it is.

as an update:
-->checked car and drove around with no filter (i know its bad)
-->checked all vac lines and removed them all and checked them in terms of can they hold pressure, no leaks
-->the ebcs is working fine as ive tested that
-->no leaks on the intake pipe but i may haved missed something tiny

questions:
can it be spark plugs
can it be coil packs
can it be the up pipe causing a holding issue? (dont think its this though) as the up pipe was loose and i tightened it just after the tune

could it be bad fuel? it was bp 98 octane

Cheers

__________________
2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe

Does it have Brant alarm? - These cut fuel or ignition when having problems.

Check all the lines around the turbo, might be hitting boost cut too, even if one of the lines has a tiny hairline split.

I went through a similar problem with my bugeye a few years ago, turned out to be the Brant alarm system.


Could be sparkies, but unlikely - check and confirm gap.
Could be coil packs, but unlikely.
Very rare to be up-pipe, unless you have the original one with the cat in it, and you've sucked the cat up to the turbo. That would be a different feeling though, the car would struggle to make boost.

If you have the stock up-pipe still, replace it with a decatted one and retune.

Unlikely bad fuel.

i have autowatch alarm system now. It does feel like fuel cut and i took my father for a drive and he reckons it sounds like the car is starving as if its nto getting fuel at higher rpm at wot and full boost

i have a catless up pipe

__________________
2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe

i have autowatch alarm system now. It does feel like fuel cut and i took my father for a drive and he reckons it sounds like the car is starving as if its nto getting fuel at higher rpm at wot and full boost

i have a catless up pipe. I am going to change the plugs next, but i took a chunk off my finger as i slipped across the intercooler! so might be a couple of days

Thanks guys!

__________________
2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe

fixed, it was the spark plugs!

__________________
2002 WRX (GDA) BUGEYE, 204BHP at 290Nm, daily driven

--MODS--
--> Walbro 255LPH fuel pump
--> Grimmspeed 3 port EBCS
--> 3" turbo back exhaust
--> Catless up pipe