Lets here it from the HTMF gearheads…
My setup: Stock 1991 305 TBI w 5 Spd WCT5
Problem: Engine randomly runs very rough and poorly. Sometimes for days at a time. It also randomly decides to run perfectly on occasion, but usually for less than 50km. When it’s running poorly, it feels like 1 or more cylinders are missing completely, and the engine jerks and shakes violently when under load at low rpm.
My suspicions: Faulty wiring somewhere… ESCM or Coil is faulty. Or perhaps I have a valve or two sticking open on occasion?
What I’ve done: Replaced the CTS and TPS and reset the computer numerous times. Checked each plug wire for spark while idling, which showed me that each plug is firing.
Timing is set to 0*. I re-timed the car this afternoon after replacing the IAC connector. I have adjusted the timing from -1* to +4* while the engine is running rough, and the problem persists. This issue doesn’t appear to be related to the timing or advance, because with the EST bypass unplugged, the engine still runs poorly and misses, with no or very little change in performance.
~ Just to note: After I re_timed the engine this afternoon, I took the car for a drive around town. The engine was running very poorly. I’m convinced at times it’s down one or more cylinders, and at a steady cruise you can feel it jerk as if it wants to go, but can’t. This leads me to believe the problem lies in the ignition. Unless valves can stick open just sometimes… Anyhow, the whole drive was fairly rough on me, the clutch and I’m sure the engine aswell. Here’s the weird part… Less than 2 blocks away from my house, the engine note suddenly changed, and the car ran smootly. I gave it some gas and I was happily thrown back in my seat. She runs fine right now, but I know tomorrow or later on tonight it’ll crap out again.
What could possibly be causing this sporatic misses?