1994 Misses/Backfires

[Spookypenguin]

Okay, to start out I have a 1994 Grand Marquis with 115k that misses/backfires

At 100k it had a slight miss when cold so I replaced the plugs/wires with generic autozone set (the miss was a little better)

At about 112k I replaced the MAF sensor and the car ran beautifully for about 2 months and now runs horribly, I have already tried another MAF sensor and that is not the problem

I have also replaced the air filter, thermostat, and the DPFE sensor (and here is where it gets weird) My car had a December of 1993 build date and I had to use the DPFE sensor from a 1993 since the 1994 was totally different from the one on my car

This car misses/sputters/backfires/chugs whenever I put it under load, rather I am accelerating from a stop or accelerating to pass and it doesn't matter if it's warm, cold, hot, lukewarm, whatever

I am at my wits end, my gas mileage is now terrible and I am afraid to pull into traffic with all of the hesitation/sputtering misfiring....PLEASE HELP! I am at my wits end

[way2old]

You might want to look into a better set of wires along with Motorcraft plugs.

[Spookypenguin]

Could my catalytic converters be clogged?

[way2old]

Does it bog down badly when it gets warm? Usually a plugged converter will shut the engine off when trying to accelerate.

[Spookypenguin]

Someone else mentioned cats, If I try to accelerate hard on the highway it's like the car can't get (or get rid of) enough air and it surges. Like I said, I'm pulling my hair out! It also has no power if I am trying to go through snow/ice, sometimes it won't even spin the tires enough to trip the traction control

[way2old]

First I would be sure the ignition system is in good shape and check fuel pressures. Low fuel pressure will also cause your problem. The converter will be last on the list for now. Rule out everything else first. Your fuel pressures should be approximately 40 psi with key on and engine off. About 30 mpsi at idle. On acceleration, the fuel pressure should rise back to 40 or a little over.

[Spookypenguin]

Thanks for the suggestions, I am going to have Autozone run the codes again tomorrow and I'll post the results

Thanks Again

[Spookypenguin]

All three Advance Auto places in town had broken OBD I readers....now what?

[way2old]

Click here. It shows how to jump the connector to get the codes. Farther down the page is the code descriptions. Good luck. Your's should flash the check engine light so you do not have to use a meter.

[slapntickle]

My 92 was backfiring through the intake. The intake was full of crud.Cleaned it and it was like new. But my problem was only after the car would start to warm up. But the loss of power under load is usually a EGR problem.