06 Legacy GT manual trans. Have tried many different things just looking for more ideas.
TYPE OF STUTTER/STUMBLE
Steady throttle/Increasing throttle/Both: Will occur under 30-50% throttle between 2000-3000RPM. Mostly noticeable 2500-3000. Can even see the tach jump up and down.
MODS
Intake:Stock
Exhaust: Catless up and down pipe
Fuel:Stock
Turbo:VF52 with Grimmspeed EBCS
Engine Management:Cobb AP
Tuner and revision of tune(if you don't mind: E-tune. Still in the tune process but he doesnt think any more changes can be made to help resolve it.
MAINTENANCE
Sensors changed:MAF, front O2,
Plugs changed:new NGK 7913 gapped at .030
Coil Packs changed:All new
OTHER SYMPTOMS
Check Engine Light:One morning it set a P2007 TGV valve stuck closed and car was in limp mode with maybe 6psi of boost during this time the stutter would not happen not sure if that could point to anything or just cause it was low on power would not happen. Ended up being a bad TGV senor. Once replaced stutter was still there.
Etc:
RESULTS
What has and hasn't worked for you: I have moved the FPR vacuum line to be teed into the BPV hose. Bought the 07 STI FPR and revamped the hoses. Has new OEM injectors. Verified camshaft timing. I own a 05 LGT auto so I have swapped several parts from that to this car like BPV, MAF, O2.
If something worked, how long has it been working for:Nothing has really changed it. Only thing to note is when using the AP is you pull 5 degrees of timing out it is worse.