Engine Performance problem
1991 Chevy Corvette V8 Two Wheel Drive Manual 58,500 miles
Just got this car this spring - I changed all filters and fluids and new spark plugs. Every thing ran great for first 500 miles, but the last 2 or 3 times I took it out for a nice Sunday drive and a problem occurred.
Car starts and runs fine when engine is cold.
After engine gets to operating temperature, I have the follwing problems:
a) Hesitates and stumbles during acceleration
b) Idle increases to almost 2,000 rpm
c) During steady cruise speed 40 -50 mph, engine misses - not enough to change vehicle speed but you can still feel it.
Hesitating, stumbling, jerking and lacks acceleration could be caused by the following: Oxygen sensor
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