JSAudi100

My '90 100 n/q has devenloped a new trick. Some mornings on my way to work the car runs about 50 rpms slower at idle than it normally does. The car's engine speed will drop to idle if you take your foot off the gas, and the engine will stall during deceleration. While it is doing this, the speedometer needle jumps slightly. Anybody have an idea whats going on. My first thought is the circuit board in the instrument cluster. I've cleaned my ISV and checked the vaccum lines....everything seems to be in order. Thanks in advance for any suggestions on what i should check....

cuatrokoop

Check the crank case and cylinder head breather system(s) for cracked or collapsed hoses. I had a plug come off a port of the 20v, which lead to horrible idle problems, veeerry long hot-starts, and stalling when coming to a stop when the engine was warm.

Your inst. cluster has nothing to do with how the engine idles, or holds an idle. You have a leak somewhere, or an engine-electrical hiccup (O2, TPS, something).

rooster 2

had some of those sympthoms. I finally traced it down to a dead cell in the battery. There was enough energy to start the car, but the computer and electronics were screwed up because of the low voltage in the system.

cuatrokoop

Would never have guessed that...!