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Discussion Starter · #1 ·
02 WRX chokes when given gas?

I have a 2002 WRX. With a 3" Invidia catless turbo back exhaust, catless up pipe, and some ebay UEL headers. It also has a cold air intake. Running a stage 2 Cobb tune.

Only code it is throwing is P0444 EVAP solenoid open circuit. Well, the the Charcoal canister has been removed and all vacuum lines on the intake manifold and intake itself have been capped off.

The problem I'm having with the car is that when idling (which is around 750rpms and it idles smooth) is that when I give it gas, it kinda chokes out and stutters? But after the initial choke clears away, it'll idle up fine. And it varies with any RPM. I can hold the rev at 3k and then punch the Throttle and it chokes out again, but idles back up and soothes out.

And when driving it, the stumble carries over too. When I change gears and start to give it gas from the low RPMs it does the same thing. Kinda chokes out but then revs up fine.

Lately it has also been kinda jerking after a boost build up and then hit the next gear. Instead of choking out, the car jerks back and forth.

I've checked all vacuum lines and they all check out. I can't find a leak. I was thinking it was a boost leak but it does the choking before even building boost.

Any ideas?
 

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For one, you're running the wrong tune for the mods you have.. Cobb stage two maps are for cars with aftermarket downpipe (or TBE) only. You will need a custom tune for the mods you have.

It sounds like you're having a problem with tip-in enrichment..
 

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Discussion Starter · #3 ·
For one, you're running the wrong tune for the mods you have.. Cobb stage two maps are for cars with aftermarket downpipe (or TBE) only. You will need a custom tune for the mods you have.

It sounds like you're having a problem with tip-in enrichment..
Thanks... I have a Cobb Tuning SF intake on the way. Looking for a stock exhaust manifold and up pipe... Hoping that will solve my issues. I'm afraid I've probably fouled my plugs out. But it's better than cracking a piston!
 

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You're actually going to want a catless uppipe.. either a stock one from a 2.5L car, or an aftermarket one.
 

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Catless won't hurt it?

And just any 2.5 car? Even N/A? Are they the same ones as the turbo 2.0s?

Nope.. the catted uppipes are known to fail, which will definitely damage things. N/A car's don't have uppipes, so no.. and the turbo 2.0L cars had the catted uppipes, which is what you don't want.
 

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Discussion Starter · #7 ·
Oh wow, I'm a tard lol. N/A not having up pipes... Lol.

It has a catless up pipe on it now, I just wonder if the oem one will bolt up to it. If it would that'd save money.
 

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Oh wow, I'm a tard lol. N/A not having up pipes... Lol.

It has a catless up pipe on it now, I just wonder if the oem one will bolt up to it. If it would that'd save money.

The OEM one will bolt up if you have a stock location two bolt manifold and stock location turbo.. but the OEM uppipe could easily destroy the turbo and potentially the engine as well. Risking your engine and about $6000 worth of repair bills doesn't make a ton of sense just to save $20 on an uppipe.
 

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Discussion Starter · #9 ·
I mean the stock OEM exhaust manifold bolting up to the catless up pipe. It's got a catless up pipe already with those headers. But I just wonder if those headers bolt up in the same location the factory exhaust manifold does, that way I don't have to spend money on an up pipe period, and can just focus on the OEM exhaust manifold and a Cobb SF tuning intake. So that my tune will be proper.

Oh, and I have an STi intercooler as well... Is that something I should need to revert back to stock for the tune?
 

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Ohh.. I see what you're saying. It should work, because most headers follow OEM fitment. I would check to make sure it has a two bolt flange on it though.. I have a set of headers in my garage that is one solid piece with the uppipe. Then there are ones with a three bolt flange, like GT Spec. And very rarely you will see one with a flange, but in a different location than stock.


The STI intercooler should be fine.
 

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Discussion Starter · #11 ·
Ohh.. I see what you're saying. It should work, because most headers follow OEM fitment. I would check to make sure it has a two bolt flange on it though.. I have a set of headers in my garage that is one solid piece with the uppipe. Then there are ones with a three bolt flange, like GT Spec. And very rarely you will see one with a flange, but in a different location than stock.


The STI intercooler should be fine.
Alright, cool. I'll check it out tomorrow and see if it's one piece or not. Hopefully if it's bolted to a separate up pipe then I'll just go ahead and find a exhaust manifold and go to town. But I do believe it may be a one piece unit unfortunately
 

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You should be able to get a stock manifold and catless uppipe for about $75-$100. Soak all the bolts with PB Blaster the night before, replace ALL of the gaskets with OEM, and re-torque the bolts after driving around the block to get it up to temperature, then letting it cool back down to heat cycle everything.
 

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Discussion Starter · #14 ·
The PO gave me all brand new Subaru gaskets. A complete kit. Almost as if he was going to revert it back to stock before he sold it to me...
 

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Better luck on local part outs or ebay?

Personally, I would scour NASIOC classifieds, and some of the larger Subaru parts for sale groups on Facebook.


Of course fixing these things may not entirely fix the issues you're having, but it is stuff that needs to be fixed regardless. If you can post a data log, and/or the learned values stored in your ECU that would help narrow down what's happening.
 
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