I know the SES works because it comes on briefly when the car is started. It does not light up when operating, so I guess that means there are no codes (don't have a scanner). The problem was initially noticed as engine temperature increased, now it's all the time but is worse when warm. I get idle variation and missing on acceleration throughout the RPM range. I have replaced the IAT, cleaned the MAF, replaced the fuel filter (which seemed to help briefly) new coil and new plugs. This is a 120K OBD1 1994. I pulled a few plugs today and they look rich. Any advice on where to go from here is appreciated.

 

Sounds like an optispark problem...

 

Would a bad opti cause a rich condition?

 

opti crap!

 

Yes, it could.

 

Hmm im also running rich and have a loss of high end power. I think ive heard that sometimes the Opti wont throw codes when it goes right? Its just kinda replace it and hope?

 

Mine didn't throw a code. I just started noticing more and more that my car would stumble after it was warmed up. Sometimes it would let a little backfire out while idling.

On another car I used to work on the idle was fluctuating or acting rather unusual compared to normal and there was a slight stumble. Again it was the opti.

Pretty much every single thing you described are the problems I have encountered first hand from a failing opti.

As many of us have said now it's your opti. Call Cromer or Dal and get a GM opti for a decent price, do a little work, and enjoy your cars restored vigor.

Ross