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Discussion Starter · #1 · (Edited)
Car: 2006 Impreza WRX
Known Modifications (by 1st owner): Turbo back exhaust, Perrin cold air intake, tuned or not unknown.

Background: I am technically the 3rd owner. I bought it from a Craigslist person(2nd owner) who bought it from the 1st owner. From what I was told from the 2nd owner, the car was bumped in the quarter-panel-bumper area under the 1st owner's ownership. The 2nd owner only bought the car, repainted it and let the car sit for about a year or so with little driving. The 1st owner drove it to about 105-110k miles and the second owner probably drove 500 miles at the most. We performed pre-purchase process and everything was good to go. There was nothing missing (that we forgot to check or do) from the pre-purchase process; we test drove it multiple times, car drove healthy, no rust, yada yada. Only thing was the rear differential was broken, which the 2nd owner replaced for us right before we purchased the car. By the time I bought the car, it had a new paint job and the dent was no where visible, although ABS sensor on the damaged side had to be replaced (no big deal.)

At the moment of the sealing of the transaction, we brought home a pretty good WRX (especially only 100k miles for a 13 year-old car.)

At the time of this post, I have had the car for about 5 weeks.
The car drove well for the first 3 weeks (I did not drive it much from the within these three weeks that I bought it home due to delays on registration and title transfer, etc.) We changed the oil with high mileage synthetic 5w-30 oil (Although I must mention that we put 0.8 quarts too much. We did end up draining some out since it is bad for the car we would think.)
Two weeks ago, on a regular driving day, the car started to sputter out of nowhere. The car jerked when you stepped on the gas, but we couldn't examine the problem on the road. At home, we tried to recreate the problem and concluded that the car would not rev over 3,500 rpm. On further driving, we specified that the problem starts when you step HARD on the pedal.


When you ease on it and hold the gas pedal, the rpm will go up slowly but everything will drive fine and dandy like a Camry.
When you are in neutral and rev the engine, it will rev almost normally to 5-6k, but will not exceed that rpm.

--When Driving
When you even start to go a little harder on the gas pedal, the rpm will not exceed 3.5k rpm (it can sometimes start at 2.5k rpm- it's a bit inconsistent). The car will jerk and sputter and feel weak until you let off the pedal. This happens on all gears.
When you floor the gas pedal, the same as above happens. Turbo, of course, does not come out.

Yes I have done my research across the forums. It seems like this is a pretty common problem, and replacing spark plugs and coils will solve the problem. In my case, it did not.
After the initial contact with the problem,

we immediately replaced the spark plugs. No change.
We changed the coilpacks to newer ones (STI ones specifically), no change.
We tried to clean the MAF sensor with a MAF cleaner (all we did was sprayed it till the little bulb was dark orange), no change.
We reset the ECU, no change.
We thought there was a wear on the wide pipe under the top mount intercooler (since the tape wrapping the pipe looked worn. I touched the inside and did not feel any cracks,) so we replaced the stock intercooler with a relatively new STI intercooler, no change.
We thought the next thing to check would be a faulty bypass valve, we replaced the bypass with a new blow off valve, no change.
We scanned for codes. These were the codes we got: P0301, P0302, P2443. (Cylinders ONE and TWO misfire codes. You can actually hear the subtle misfire if you listen carefully when the car is parked neutral,)
We did a compression test due to those codes. The numbers were 148, 148, 148, and 145 (all healthy numbers.)

The next targets would probably be the cam and crank sensors, then the turbo itself, then injectors, then last would probably a professional tune.
The golden question: does anyone have any ideas on the things we've checked, will check, or listed in the post? Any ideas will help!
I tried my best to provide the most accurate history and activity details as possible. Please do ask if you need more information.
Thank you so much!

15,475 Posts
IMO, you answered your entire spiel in the first sentence.

You have modifications and don't know if the car is tuned. That would be my first focus.

2006 Subaru WRX
22 Posts
i have had basically the exact same issue with my 06 wrx. Did you ever get this problem resolved?? any feedback would be greatly appreciated of course.
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