Car won't accelerate if gas pedal is pushed too far

Asked by GrandPrixMcGee Dec 01, 2018 at 01:02 PM about the 1997 Pontiac Grand Prix 4 Dr GT Sedan

Question type: Maintenance & Repair

My car will accelerate when the gas pedal is lightly
pressed, but if the pedal is pushed roughly a
quarter of the way down or so, it will stop
accelerating. The car wont shut off, but the engine
sounds like it's in a really rough idle. I've already
tried replacing the mass air flow sensor and the
fuel filter, but to no avail. The car idles perfectly.
What pieces should I look through next?

2 Answers

18,685

Could be a number of things. Don't replace any more parts until you find the problem unless you just like spending money in which case continue as you are. I'd have the catalytic converted checked to see if its plugged. Also make sure the spark plugs are in good shape. It's easy to forget about them these days and not change them ever. They do wear out and if they're way far gone they can make the engine act like that. And have it scanned for trouble codes. I know its an old car but there is information being saved in the computer.

26,835

I would start with the cat converter and find the problem or eliminate it from the equation.

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