BlackWagon GT

Saw a DGM spec.B with quad-tip exhaust heading north Thursday afternoon 4:40-ish on 355. Also saw a stock-appearing spec.B last Saturday night parked in Libertyville on Interlaken. You may have been attending the same party I was?

Discovered something tonight that may be of relevance. The engine has noticeable roughness between 1700-2500rpm under no-load conditions. It's not as pervasive or intrusive as while driving, but definitely still there and the RPM range matches almost identically. Any ideas on what could cause something like this?

Saw a gray LGT going south on Meacham between Golf and Higgins today. Made a right turn into an apartment complex.

I confirmed the manifold gasket leak when cold, but it looks like it seals up again when the engine gets up to operating temperature. I think my next step will be talking to my local shop and getting their take on it. I'm about out of ideas.

Cleaned the MAF today. The IAT had filter oil all over it. Thanks, K&N! When cold, it didn't feel much different, but after some drive time it seemed to improve significantly. I suspect the cold roughness may be related leaking intake gaskets. The rubber seemed a bit hard and I saw some residue around the mating flanges; I'll have to test for vacuum leaks at some point.

Update: I added timing into my low-RPM/low-load ignition table based on NSFW's data and it made no difference for me. It still has that rough misfire-like feel through the same RPM range as I noted previously.

TYPE OF STUTTER/STUMBLE Steady throttle/Increasing throttle/Both: Steady, light throttle; around 2000-2500 RPM MODS Intake: None Exhaust: None Fuel: 93 Turbo: Stock Engine Management: Cobb AP Stage 1 Tuner and revision of tune(if you don't mind): MAINTENANCE Sensors changed: None Plugs changed: ~36k miles ago, according to what I was told Coil Packs changed: No OTHER SYMPTOMS Check Engine Light: No Etc: Intermittent slight hesitation when transitioning from deceleration or light throttle to part-throttle. RESULTS What has and hasn't worked for you: I haven't tried anything yet as I don't wan to just throw darts to try to fix the problem. I've been logging and analyzing different sensor data sets trying to find something anomalous but I haven't found anything obvious. I loaded the Stage 1 as soon as I got the car but, I don't remember or didn't notice the surging on the test drive(s). If something worked, how long has it been working for: n/a

Yesterday I saw a gray spec.B on NW highway through Palatine. Gray STi rims, quad tip exhaust, Pelican Parts plate frame. I was in my company car at the time, so you wouldn't have recognized me.

I see an OBP 2.5GT sedan street-parked on Sterling in Palatine quite often.