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2002 WRX idles fine. Stumbles on acceleration. Builds boost fine.

7K views 12 replies 5 participants last post by  m4a1steaksauce 
#1 ·
When I bought the car it had 9 codes...

Well, I've fixed them all so far except these two reoccurring ones... And it's weird.

I have a Cobb Accessport (I'm running a stage 2 map. Intake, turbo back exhaust, STi intercooler) and some generic OBD-II scanner. Both of them only read one code. But they both read different codes.

The AP reads P0444 (Evap) issue. The car (previous owner) has a deleted Evan system. The air filter and intake ports have been plugged off. Only one vacuum line that I can find leads from the deep middle of the intake, up into the top middle nipple of the intake. I've searched online and it looks like it's been done properly. But I see the connector just laying there with nothing to plug into.

So I have no clue what else I can do with it. The OBD-II on the other hand is showing up a P1088 code. A driver side TGV sensor going bad. I JUST fixed my P1089 code (TGV sensor on the passenger side.... Pita!!!) So now I have a TPS sensor on the way to replace this one. But I'm afraid after I replace it... Nothing will change.

The car cranks up and idles fine. Maybe idles a little low sometimes, but nothing unusual. (replaced the IACV) but even when idling, if I give it gas, it's like the car "stumbles" or hesitates and feels like it chokes out. But as soon as it gets over the stumbling it revs and builds boost perfectly normal.

When driving, I'll change gears and the car will act like it's choking up, and stutter (the car literally feels like it's jerking back and forward) and then starts revving normally and builds boost fine and takes off. All is good until the next gear change... Then the process repeats.

If I let off the clutch VERY slowly and smoothly, then apply the Throttle VERY slowly and smoothly, it'll pull fine without jerking. But if I quickly stomp it, it'll choke up and shake back and forth. It's super frustrating.

I literally can't figure it out. And the sensor won't be here til Friday. So my fingers are crossed that it solves my problem, but I feel like it's just another wasted effort.

TL;DR: Car idles fine. But "chokes" when given liberal amounts of throttle, stumbles at first, but then gains RPMs normally and builds boost fine after it revs out of the choke. Does this at idle, and after every gear change. Replaced passenger side TGV sensor, IACV, double checked the EVAP delete, and STILL can't figure it out!
 
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#2 ·
you can get can delete the codes from the ECU alltogether so they will never show up. this is supposed to get done when the evap system was deleted but it looks like it wasnt done.

as for the TGV sensor, it could just be old and busted. it is 14 years old afterall. the stumbling and choking definitely sounds like a TGV problem.

another option is to delete the TGV's alltogether and again delete the code from the ecu.


and i dont just mean clear the code, i mean go into the ecu and delete it from the registry. you can do this with a Tactrix and RomRaider. or any tuner can do it for you but im sure they will charge. but it sounds like you should get a pro-tune anyways, so they would be able to deal with it then.
 
#5 ·
They don't have AccessRace Tuner anymore. Only the Accessport Manager and I have to watch 4 hours worth of videos and take a test about the videos?

So maybe the 8 dollar cable would be a better bet? I'm already constricted enough as it is with time lol. Work, college, and now this damn WRX... Lmfao
 
#6 ·
You can't use Romraider or any other cable to take out the codes an run a OTS Map off of the Cobb AP at the same time. Send out a message on a FB page an see if someone can send you a copy of the program. I still have my copy but it is for the 05.
 
#10 ·
You can modify the Cobb OTS Maps with AccessTuner. Although the software isn't available unless you take a class there are people out there that have the program an are usually willing to send a copy if you need it.
 
#9 ·
Hey guys, thanks for the help. Finally got all the codes fixed with the car dealing with the TGVs. Still throwing P0444, and the car still acts up, albeit not nearly as bad.

The one thing that helped me A LOT was ripping out this Turbo Smart manual boost controller the PO had on it before, and swapped it back with the factory restrictor pill. It now pulls wayyy better than it used too.

It just kinda hesitates when applied throttle or gear changes, like before, but it's tamed down quite a bit.
 
#11 ·
well ya technically, but its not directly available to the public anymore because cobb doesnt want un-educated people messing with their maps and blowing things up lol.
 
#12 ·
Get your IDCs checked/Wideband A/F ratios looked at. My bugeye does this (no P0444) but I know my 565s are acting as 370cc. Stay out of boost, make sure your cat isn't clogged, and check for oil in the intercooler (will coat the o2 sensor). Learned from experience, and still fixing things myself.
 
#13 ·
For what it's worth, I had stumbling problems with no codes except for an occasional misfire code if ran a little hard. 2002 WRX 148k miles. My spark plugs had gone bad. I'd like to assume that they were never changed. Symptoms sound very similar, stumbling on start of acceleration and deceleration but smooths out after. Shifting was also jerky because of the plugs. I would definitely check your spark plugs unless you know they have been recently. Just my $.02
 
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