We set timing last week to 8*, but noticed the mark was jumping around every couple of revolutions between 4-10* What would cause this most likely? A search on the net points to the distributor on quite a few cars, though none specifically mention the Fiero. I have been told vacuum (all lines intact and clear), cam shaft gear (was told when it goes, it just goes) or distributor. I cleaned up all the grounds today.
What about the coil? I noticed the car sounds like it has a miss listening to the exhaust while I burped the cooling system. Since the ECM controls the advance, is that a possibility? I get code "12" and it notices when sensors are disconnected, so it seems to function properly.
Would I be better off at this point buying a ALDL connector w/software so I can see what the car is doing while running?
I'm not sure if the ALDL will tell you why the timing is jumpy. Isn't the jumper you use to set timing supposed to eliminate influences from the ECM? However, getting an ALDL cable and software is a good thing to do. If you're into troubleshooting and fixing things yourself, it's a mighty handy tool.
Yes the jumper is supposed to eliminate that, and it was jumped with it in that mode as we set timing. I really suspect the distributor as my symptoms align with the ones I've read, but like I said, other GM/Ford models.
Couldn't find anything here or online with a Fiero having this issue.
Forgot to mention I can feel it if I'm at a cruising speed, like between 40-50 MPH, I feel the car pulsing. Though the tach nor Speedo show any movement in sync with the pulse. Like a slight stutter/jumping.