Hi all, Recently I have felt some shuddering when accelerating, especially when either WOT at high RPM or low throttle at lower RPM (right around the 2800 stumble mark but also higher depending on throttle). I am running the Stage 1 91 + CPF map (with a Cosworth Panel Filter of course) and 93 octane from BP. I always fill it at one of two BP in my area, and only use 93 octane. I logged a 3rd gear pull today, and don't see any feedback knock or fine knock learn, but my Dynamic Advance numbers start at 5.62 (2828 RPM) and stay there pretty consistently until I let off the throttle at 6074 RPM where they are 4.64. Does anyone have any idea what I am feeling? I have 54,000 miles on the odometer and am gun shy about these engines. I have always treated it well...I don't mash the gas at low RPM's or get close to redline. I only use Rotella T6 5W-40 and change at 3,750 with a Subaru filter. Thoughts? I will bring it in...but wanted to get this groups thoughts. Oh - and I also accidentally drained my battery a couple of weeks ago and I think that reset the ECU so it has relearned since then. Could that cause this? Should I unplug the battery and reset it again? If this gets any more thoughts...datalog is below: https://onedrive.live.com/redir?resi...int=file%2ccsv And this is a very recent development. I am aware of the GR stumble repair kit that also requires a pro tune. I deal with the stumble normally, but these feel different. It's like the engine is pulling back timing or losing power. Thanks!
I've had iridium plugs go bad at 70k miles. Similar issues to what your describing. If you're burning oil, they'll go even faster.
Interesting - I guess I will bring it into the dealer since it still has a few thousand left on the powertrain warranty. Although I don't relish the idea of going back to Bloomington Subaru. Have had pretty spotty service there everytime I go, but it is so close to my work that nothing else really makes sense.
I get this issue/something similar in my 2002 wrx when my mass airflow censor is dirty. I typically have to clean mine every 6 months. A can of MAFC cleaner is pretty cheap and the cleaning is a super easy DIY. Just make sure you don't actually touch the censor with your fingers.
Excellent idea on the MAF sensor! I have not cleaed it for probably 1 year. I will do that tonight!!!!
You could have a blown Ringland. Iv seen several cars with blown Ringland pull timing because it's picking up false knock. Pull the oil fill cap while the car is idling. If you see smoke it's likely a Ringland and you should do a compression test to conform. Or could be a bad plug or coil pack
I cleaned the MAF sensor...and it made a HUGE difference. It feels totally normal again. I will remember that for next time. Thank you Thomas Franz!!!!
