Engine Performance problem
1999 Chevy Lumina 6 cyl Front Wheel Drive Automatic 91,000 miles
When the engine is hot, the car bucks like crazy, RPM's fluctuate madly from maybe 3,000 to 300. When the car is first started this is not a problem. Seems worse after driving for a while and shutting the car off and restarting. This never happens at idle speed only when driving and especially when trying to accelerate. I have tried changing the fuel filter, oxygen sensor, even the fuel pump(which is no small task). The plugs and wires, caps and rotors are fairly new. Just after changing the fuel pump I got a check engine light and had it scanned and the code PO 452 came up. I looked up this code and it states that the evaporative emmission sensor has low input. Nobody seems to know exactly what that means. Have looked it up on numerous web sites and have not gotten a difinitive answer.
However, I do not think that is the causie of the bucking and shaking. Can anybody help with this?
Could it be exhaust restriction. Seems like if it were that it would happen all the time, not just when the car is hot.
have the same problem?
Wednesday, June 23rd, 2010 AT 10:55 AM