QuestionI have a 94 grand prix 3100. my wife brings it home running ruff,stalling.The next morning I have a look to see if there is an engine service light on,none.REading through the rebuild book its all trouble shooting,had it on the computer,nothing. This is what I did,fuel presure test(good)intake leak spraying carb med for leak,none. The engine when started will idle at 2800rpms comes down to approx 2400rpms gets hot want to stall,if I spray carb cleaner down trottle body brings engine rpm up repeat 3 or more times,with Iac & tps disconected runs great, cleaned tps lots of carbon residew. Then I get intake vaccum of 8psi (with ever thing pluged back in 47psi 2200rpms,170,000kms,intake gasket was done,approx 15,000 kms ago.The exhaut is weak pressure,changed the termo stat to 185,cracked back exhaust manifold,to be put on with new oxegen sensor.)
AnswerHi, the pressure is to hight for the RPMS, the pressure should go down when the rpms gose up, then the pressure should come up when the rpms comes down, check the pvc valve it could be clogged, the tps should not have carbon or residew, the Iac valve should have the carbon and residew, the Iac valve could be stuck open and causing it to get to much air, and this would cause the hight idle.
