I posted a problem in December with my '94 940 n/a, 210k miles, having an intermittent missing problem while driving. At that time, the distributor cap (Bosch), rotor (Bosch), plugs and wires (Bougicourd) were all new. Since then I replaced the distributor cap again and the power stage. I replaced the distributor cap because I could see spark at a particular angle. Am I missing something that should be on the cap? I didn't think I should see spark in there. I also put a timing light on all of the plug wires. The problem does not seem to be limited to any particular speed or engine load. When the timing light was on, I noticed the miss appearing in park while idling. At some point or other, all of the wires had at least one miss according to the timing light. So I figured it was a spark distribution problem.

I seem to be down to either the coil or the RPM sensor. The question I have is which one. Here's an interesting twist - when I bought the power stage, I ordered an off brand (Huco brand or something like that). The off brand product actually made the problem worse. I exchanged it for a Bosch and the problem seemed to go away for awhile. I just had the car on a 1,500+ mile trip and it is now missing more frequently.

It feels like more than one cylinder is missing because the car usually jerks a little as if it loses power and regains power in a half a second - more so than I would expect to feel if only one cylinder was missing. Again, it's not limited to a particular speed or engine load. I just don't want to be left sitting somewhere along the road. I was told by fellow brickboarders that the fuel pump relay or radio suppression relay may also be the cause, but given my timing light test, I'm not so sure about those relays being the culprit. Any tips are appreciated.