Hi everyone,
I have a well-worn 92 Jetta with a 1.8L RV engine. The car starts fine and for the first ten minutes or so works flawlessly. Once everything heats up however I am getting erratic misfiring on all cylinders. It doesn't seem to matter where the throttle is or how much load is placed on the engine. The misfiring can be a single blip or a full-blown 10+ second epileptic seizure to the point the engine quits. Along with the misfiring the tachometer also wanders through almost it's full range.
My first thought was that the ignition coil had a broken wire or dodgy internal connection that got worse as the unit heated up. I replaced the coil, distributor cap, and rotor - no change. The grounding strap from the coil bracket to the engine is also fine.
I'm stumped and don't want to start replacing everything in the car till I find the right component. There must be a procedure I can use to isolate the problem.
Can anyone offer advice as to the next steps I could take?
TIA for all the replies.
DarylS