Hello all,

I have had a perplexng problem with my 1992 Cutlass Ciera S 3.3v6 for the last month. Intermittently, the car will run rough, blowing black smoke out of the tailpipe. When this happens, the speedometer stops working and the Check Engine light comes on. Then, it all goes away. The car is not setting any codes, so it is a true mystery. I have thought about a faulty PVC (Chilton's points to it), but the location of that little sucker has yet to be found.

Could this be the ECM?

Thanks

dought its your ecm. Start with your IAC or your MAF. if the check engine light comes on there would almost have to be a code? Dont know why a sensor that would make your car run rich would also make you drop your speedometer though. That may be the VSS but I wuold try to first get your car to run at 14/7 air fuel like its supposed to steadily then see if your speedo cuts out anymore. dont worry I have not found my pcv valve on my 93 ciera (3.3L) either.

PVC is usually located on the rear valve cover for the V6 engines.

Your ignition coils is probably failing.
You fuel pressure regulator diaphragm could be ruptured and allowing excess fuel to get sucked into the intake manifold causing unburned fuel to get burned in the catalytic converter and shows as black smoke.