1994 Pontiac Grand Prix

Engine Performance problem
1994 Pontiac Grand Prix 6 cyl Front Wheel Drive Automatic 160000 miles

For the past few weeks I have had a problem with this car idling at 1600 r.P.M.S It was annoying but drivable. I suspected MAFS sensor or air temp sensor. I cleaned them with carb cleaner spray and now the car will not idle below 2600 R.P.M. Before using the carb spray, I steam cleaned the engine as it was very dirty, then drove it 20 miles home with no problems. I have blown out all connections to sensors with compressed air in case there was water in them. Any ideas where to go from here?
Jay Davis
March 11, 2009.

Hi Jay,

Check for vacuum leaks and also check the IAC (Idle Air Control Valve).


Mar 11, 2009.
Just wanted to update this, I found a massive vacuum leak behind the throttle body. The tube which ties the PCV vale and the Evap canister to the intake manifold has a grommet built onto it which slips into a hole in the top of the intake. This grommet was gone! G.M. Wanted $30.00 for the tube assembly. I found a $2.00 grommet at Napa which fit Very tight and solved the issue. Also I found the EGR port which is cast into the intake manifold was totaly plugged. I cleaned this out and installed a new EGR gasket, This morning on my 20 mile commute the check engine light stayed off for the first time in years!

Jay Davis
Mar 17, 2009.
Good Job

Mar 17, 2009.