My Volvo 960 idles low and rough. The diognostic code is PO172. (fuel too rich) it's either too much fuel or too much air, according to the auto part store. I think it might be the intake manifold gasket. Is this accurate, or am I missing something?
low and rough idle on 1996 Volvo 960
by Devan C in Dalton, GA on April 03, 2010
ANSWER by lawrenceg , April 04, 2010
A leaking intake manifold gasket is very common on this engine. The way I find it is to get a water bottle and spray a stream of water around the intake runners where they attach to the head. They normally leak at the ends,, near the #1 or #6 cylinder intake runner. If the gasket is leaking, the engine will stumble when the water is drawn into the cylinder from the vacuum leak.
ANSWER by M_Kast , April 03, 2010
An intake manifold gasket implies a vacuum leak. It is possible that there is a vacuum leak, but there are some other things that could be wrong as well. 1) TPSensor 2) O2 Sensor