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Discussion Starter #1
Hello all so time for my first 'real' post. I recently went and bit the bullet and bought a 2002 wrx 'bugeye'. I've had the car about a week have to say right off the bat I love it. There is however 1 bug that I'm trying to massage out of the car. But first I'll get down to the specs:

-2005 ej255 engine (longblock swap from a forester xt) with 180 000km on it. Compression is 145-147 across the 4 cylinders.
- 565cc injectors
- invidia CAI
- Injen up and (catted) down pipe, 3' all the way to the back
-RBV is vented to atmopshere but it is tuned for this
- V2 cobb accessport
- stage 2 clark turner custom tune (for all the above mentioned bits)
- Throttle body and tgv's are wrx, but the intake manifold is from the ej255.



Otherwise rest is pretty much stock 2002wrx bits engine and electronics, stock ecu, fuel pump, transmission, ect. (the body and tranny have about 250 000km on them for reference but the transmission feels really nice and tight still. Shifting is smooth(ish) (first sometimes needs a slow, gentle loving touch but you all probably know about that).


Now onto the problem: First off it is erratic which is making it a bit hard to pin down. So in a nutshell when it is running poorly it pulls normal until about 3000rpm but then the whole car starts to shake when I give it gas, turbo makes a bit of a funny noise (just sounds different) and the car basically makes what feels like 40% power :(. This typically occurs when I first start the car (note I always let it warm up to full running temp, usually via idling, before I start testing any of this stuff, so this is all fully warmed up engine stuff) and it lasts for awhile around ~20 min (roughly). The shaking is MUCH more pronounced in the higher gears (see 4th + 5th) and occurs with basically any significant throttle input between 3000-4500rpm (I usually can't get it to rev any higher due to lack of power). The car will SLOWLY accelerate at a crawl and climb through the revs in say 3rd. It does so the best at about 40-75% throttle, increasing throttle slowly with the revs. When it's running really poor it will have a hard time breaking 120km/hr in any gear. It doesn't seem to be lacking boost when I'm watching it (I've done a series of datalogs that I'll hopefully post up here either later tonight or tomorrow morning). When it is running like this if I get the RPMs up (over 3000rpm) and hold it there with just a feathering of the throttle, aka enough to maintain my speed but nothing more, then there is no shudder. As soon as I put in more than say ~5-10% throttle (enough to try and accelerate) however, bam back to shudder and no power.

Now, once it seems to start running well it is great. The turbo spools up and just stays pulling strong all the way through. Furthermore, once it is running great, it pretty much stays that way until I turn the car off again. Now when the car is running well the thing freakin' hauls. Once that turbo starts to crank at 3000rpm it just rips until ~4500rpm where it starts to run out of breath a little bit as it approaches 5000rpm then she wants to shift. When it does this however it feels SUPER smooth all the way through the revs, there is no shudder or shake of any sort. At this point The car is lots of fun to just play in around the 3500-4500rpm range, it just pulls like a beast in 3rd and 4th and is a tottally different animal compared to when it is all shuddery.

I'm slightly suspect of electrical (not that I know all that much) as it seems to be tied to shutting off and restarting the car. For example, pulling in and filling up the other night it had been running great, then shut off to refuel (put 91 of course), then it ran like poorly for about 10-15min before gradually improving back to normal.

Note by running poorly I'm refering to the lack of power and shudder above 3000rpm. Asides from that the car ALWAYS idles great (hot or cold), never stalls (say shifting from 2nd into neutral coming to stop, it just slides smoothly down to 1000rpm and sits there).

3 days ago I cleaned the MAF using maf cleaner (sprayed, soaked in a baggy of the stuff for about an hour then resprayed) let it dry and cleaned inside all of my air intake pipes leading up to the turbo. I then reset the ECU and let the car relearn by idling from cold to hot. Shut off, restarted, and did a variety of driving (~3hours) starting with mellow out of boost and slowly building until in boost/spirited driving for the last 1.5hrs. Although this helped and decreased the amount of shudder/period of time before car runs good the issue is still present.

So any suggestions/ideas about what might be going on?

P.S. for test conditions it's all been similar, dry pavement and at ~ -20ish so heatsoak is definitely not an issue XD

Cheers,
CBR
 

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Discussion Starter #3
So here are some of the data logs for the car.

https://drive.google.com/folderview?id=0B6pgdjY4LZlwNGlrRjBYTG5pN3M&usp=sharing

I've color coded certain sections for ease of reading. In a nutshell Datalogs 1 and 2 the car wasn't running well. Log 1 is a pull from second to third then to fourth on the highway.
Log 2 is shortly thereafter on the highway and is a 5th gear pull.

Log 5 is when the car is running great and really hauling A$$. I went 1-2-3-4 pretty hard on the throttle. There was no shudder and the car accelerated super smooth (and quick). I then drove in 4th a bit and did a few roll on's in fourth and the car felt really good and punchy/peppy. These sections I've also highlighted.
 

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I know this has been up for a few years now but just wondering if you figured it out at all? My 99 wrx does the same thing and I've change fuel reg thinking its that but still does it and maf is new, i saw on another forum that it could be the waste gate actuator and thats next to check or even a leak behind the maf in the intake. Any info would be really helpfull with this as i miss driving her the way she should be.
 
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