I am currently in the process of diagnosing my distributor as a potential reason for low RPM stumbling and knocking, etc. My car will run, however at very low RPMs it will stall out (650 when I am in closed loop).

Even though I have spark at my ignition coil wire, I still tested for voltage at the harness connector terminals A and D (ICM disconnected, the coil plugged in, igntition mode). I am showing no voltage at either terminal, which is a point of confusion for me. Without the low resolution signals, the engine shouldn't run, correct?

Also, regarding the distributor, I am not getting an SES bulb or any DTCs (using the cheap loaner code puller from the local autoparts store). The coil checks out for continuity and the ICM was also tested and is w/in spec.

I recently (Feb.) replaced all of my spark plugs and wires, at which point my idle and throttle response seemed outstanding. Since my symptoms have started, I have pulled them all, verified proper gap, and made sure none of my wires were crossed or burned. I also used a wire brush and electrical contact cleaner on the coil wire connector when my ICM was pulled.

Any ideas as to what could be causing my stumble, knock, hesitation, surging, rough idle, etc.?

Thanks for any input or direction!

 

EGR stuck open????

 

Although at this time I can't properly test the EGR vacuum properties, the diaphram depresses fully and seems to come back out all the way when I let off. At idle (when depressed) it sounds like the RPM drop off a little bit and doesn't stall; exactly like how it sounded when I have pressed on the EGR before when nothing was wrong. I'm guessing that even if my EGR system was the culprit, the severity of my symptoms would not be nearly as great. However, seeing as I can't pinpoint what the problem actually is, EGR was worth checking on

Maybe my cap and rotor aren't consistently getting 25,000 V due to either a faulty coil wire (?) or some sort of malfunction in my PCM (??). I'm not sure I could back the theory behind that last hypothesis, but maybe someone else could...

There is also the possibilty that I have some moisture/buildup/whatnot inside my optispark, but it seems like if it was interfering with a signal to the PCM that it should throw a code. What all EXACTLY will set off DTCs 16 & 36?

Also, I still haven't resolved the issue of why I am not showing any voltage at terminals A & D. Yes, multimeter was in DC.

And for those who might be wondering, no access at this time to a laptop (therefore scanning software); it'll be a couple of weeks.

Thanks for your help so far!

 

Are you sure you are measuing A and D? Look closely at the connector. The cavities are labeled A B C D. The car would not run if you were not getting voltage to the coil.