Stuttering / missing on track
 

My '91 started stuttering / missing at the last DE and I'm trying to track down the issue. Some background on the car:

- '91 1.6 with 140k miles
- Greddy kit
- Emanage blue (piggy back) with the OlderGuy Autotune
- precision 350 intercooler
- walbro 190 fuel pump
- Vortec FMU

I was running 10-11 psi on the track. It started stuttering mid-session, looked like it was low on gas. I came in, filled up, titghtened some boost couplers in case that was the issue, and prepped for the next session. I went out and the first 3 laps it ran great, then it started degrading from there. Same with the ride home, fine until halfway into the drive.

The stuttering occurs when I'm full on the throttle around 5k rpms and up. Partial throttle usually helped clear it up.

Im leaning towards spark blowout as my culprit. Plugs are gapped at ,028. I was going to do plugs, wires and a new coil to see if that helps. Part of me thinks it's time to get a COPS setup but I'm afraid of adding complexity before I can diagnose and solve the original problem.

Would love to hear your thoughts on this one.

Did you pull the plugs and check them? My friends car use to foul plugs and it would exhibit this same behavior and slowly get worse as the plugs fouled (his tune was super rich, causing the fouling)

They all look fine. I did notice one was gapped a little bigger than the rest (.028 vs. .031) which coupled with the fact that they were BKR5E could have caused the problem. I'm going to throw in some colder plugs and a new coilpack and see if it resolves itself.