Engine Performance problem
1993 Oldsmobile 98 6 cyl Front Wheel Drive Automatic 167000 miles
I have a 93 olds 98, 3.8L engine. Approx 167,000 miles. The car seems to run fine during idle, but upon acceleration, it is sluggish and runs as if it is missing a spark plug. If I push the gas pedal about 1/2 way down, it backfires (almost constantly), and is very sluggish, with almost no power, especially on an incline. I have to press the gas pedal completely to keep it from backfiring and to get any power out of it, and even then, it runs as if it is misfiring.
I have spark on all of the coil packs. I had NAPA check the ignition module, and they said it tests fine. They tested it twice in case it failed upon heating up, but it tests fine.
I have replaced the plugs and put on different plug wires (not new ones, but ones from another car that runs fine)
I have removed and cleaned the air flow sensor.
I have tried to jump the OBD connector to get at the codes (I don't have access to a pre-96 code reader), but could not get warning light to blink as if it was working.
Lacking acceleration, hesitating, jerking, stumbling -could be one of the following below
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