Engine runs rough at all speeds. No engine codes showing up. Changed spark plugs and wires problem still there. Engine is not overheating. Idle seems to be high around 1000 rpm. Kind of runs as if there is a vacuum leak but so far I can't find a leak. Engine seems to start ok. Problem just appeared. I don't hear and odd engine knocks or noises other than some valve tapping noises, but that has been there since I bought the car.
Engine running rough on 1995 Oldsmobile Cutlass Supreme
by Randy95 in Proctorville, OH on December 03, 2010
ANSWER by DaveJM on December 03, 2010
Sounds like a vacuum leak or a sticking idle speed control motor. You have the right idea. Keep looking for any disconnected hoses, air tube cracks, etc....
Car just started running rough, run good for about 15 miles stopped at a light started idling rough then on take off it really run rough.
The fuel pump may fail causing engine to stall and not restart.
A idle and stalls when you come to a stop . How do I fix this when I disconnect the battery's?
The engine vacuum hose to the MAP sensor may crack resulting in a vacuum leak causing the engine to run rough and/or stall.
The upper intake manifold gasket and/or a PCV vacuum lines/hoses can develop vacuum leaks with age. This type of leak can result in a higher that normal or rough idle.