mftsc40

My wifes car (a 92 grand prix 3.1) started backfiring on take off but smoothed out on the freeway. I thought that she got some bad gas ( in the car lol) and added dry gas. I also changed the plugs and wires. The problem persists. Any Ideas? this problem started overnite.

tblake

ok, lets first clarify something here. You say backfire, but a backfire is actually firing out the intake. Much like a distrubutor timing is off, and the spark happens when the intake valve opens. What i think your having is explosions happening out the exhaust. Correct me if im wrong. Possable cause is overfueling. Maybe a sticking fuel injector, or a bad fuel pressure regulator.

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2000 Pontiac Grand Prix GTP
(3.5" Pulley, DHP 1.0 PCM, ZZP 2.5" High Flow Downpipe, MMS Ported and Polished Lower Intake Manifold, ZZP Stage 1 Ported Throttle Body, 180° Thermostat, NGK Iridium TR6IX)


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