Engine Performance problem
2003 Chevy Venture 6 cyl Front Wheel Drive Automatic 75000 miles
The car hesitates when I move from the brake to the accelerator just before coming to a complete stop. I've checked the fuel pressure and it was within spec. I've also replaced the IAC valve to no avail. Not sure what to try next. No problems when accelerating any time other than just before the car comes to a complete stop. Service engine light is on with a Camshaft Position Sensor out of range code. I've actually replaced this sensor but the light is still on. I'm guessing it is either the wiring to the sensor, the connector or the PCM, but I am assuming that this is unrelated to the performance problems since car/engine sound fine other than this one issue (please let me know if you disagree). Any ideas?
April, 29, 2009 AT 9:23 PM
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)
Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include: Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
April, 30, 2009 AT 7:44 AM
Thank you for your response. One thing that gets to me about all of these suggestions (and I forgot to mention this in my original post) is that if when I take my foot off the brake I allow the car to coast for a second and then gently ease into acceleration, the car is fine. If, however, I immediately hit the accelerator (after removing my foot from the brake) at a normal start from a red light type level (without the gentle easing or the allowing to coast) then I hit the problem.
So when I think of a TPS, or any other sensor for that matter, I tend to think that the gentle touch would exacerbate the problem as opposed to making the problem go away.