Whether you have a trusted technician who works on your vehicles, or you prefer to do the work yourself, let ACDelco help you keep your cars and trucks running strong, long, and efficiently.

Performance Problems

Knowing something about how your vehicle performs and handles makes communicating with service advisers and technicians fast and easy.

Performance Problem	How to Describe It
Cuts out	Temporary, complete loss of power. Engine quits at sharp, irregular intervals. May occur repeatedly or intermittently. Usually worse under heavy acceleration.
Detonation	Mild to severe ping, usually worse under acceleration and load. Engine makes sharp, metallic knocks that change with throttle opening. Sounds like marbles rattling around.
Dieseling	Engine runs after ignition switch is turned off. Runs unevenly and may make knocking noises.
Hesitation	Momentary lack of response as accelerator is pressed. Can occur at all speeds. Usually most severe when starting from a stop. May cause engine to stall.
Missing	Pulsation or jerking that changes with engine speed. Exhaust has a steady spitting sound at idle or low speed. Not normally felt above 30 mph.
Rough idle	Engine runs unevenly at idle. Car may also shake.
Sluggish	Engine delivers limited power under load or at high speed. Won't accelerate as fast as normal. Loses too much speed going up hills. Has less speed than normal.
Spongy	Less than anticipated response to increased throttle opening. Little or no increase in speed when accelerator is pushed down to increase cruising speed. Continuing to push pedal down will finally give an increase in speed.
Stall	Engine stops running or dies out. May occur at idle or while driving.
Surge	Vehicle speeds up and slows down with no change on accelerator pedal. Can occur at any speed.

Here is a troubleshooting checklist that will help you document problems with your vehicle. You can give this checklist to your counterperson, service advisor, or service technician when you take your vehicle in for service.