misfire misery

[97expV8]

Yeah I like to keep her happy. She's one of the good ones. She knows I'd be unhappy if I didn't have my mustang running and able to race. She gives me a lot of room to do things to the car to make it faster and whatnot. She enjoys going to the drag strip and racing.

Then there ya go, easy decision!

 

[james1989mustang]

Did you check the fuel injector or wiring? You never can tell. I would never have thought of all things a rat chewed the wire in two. Can you smell gas from the intake area?

 

[97expV8]

Did you check the fuel injector or wiring? You never can tell. I would never have thought of all things a rat chewed the wire in two. Can you smell gas from the intake area?

Haven't checked the injector yet, that was going to be next area after trying to swap coil packs for final verification it isnt ignition. Also wanted to check vacuum on it as well.

 

[97expV8]

Haven't checked the injector yet, that was going to be next area after trying to swap coil packs for final verification it isnt ignition. Also wanted to check vacuum on it as well.

Well swapping the coil packs got rid of P0303 code and it idles smooth again, but still backfires a little under a load...yet no new codes popping up after a half hour drive. Guess I'll check vacuum and the injector wiring next. Then maybe the compression on the remaining cylinders I skipped last weekend, only checked #2,#3, and #4 since I thought my issue was #3.

 

[97expV8]

Well swapping the coil packs got rid of P0303 code and it idles smooth again, but still backfires a little under a load...yet no new codes popping up after a half hour drive. Guess I'll check vacuum and the injector wiring next. Then maybe the compression on the remaining cylinders I skipped last weekend, only checked #2,#3, and #4 since I thought my issue was #3.

vacuum was fine....and even tried the paper test on exhaust and it went good......i'll find this backfire culprit sooner or later, until then the Exp sits in driveway other than short test-drives etc...

 

[Turdle]

I'm afraid mine is a burnt valve. I had mine idling and put a piece of paper up to the end of the tailpipe and it sucked up to the end of it quite a few times. I've got a good friend who is mechanic who is gonna let me borrow a compression tester to make sure. But I guess I'm gonna look into getting my heads rebuilt. I hope you have better luck John.

The paper test does not always indicate a bad valve. A blown head gasket can also cause the paper to suck in

You really need to check compression on that cylinder., then the cylinders around it to determine if it is an internal problem.


Also, you need to use a test light ( led) on the injector harness to be sure the injector is getting it's power. Could be another rat got hungry further up the harness.

If the injector was indeed dead on that cylinder and run for any time I would suspect the piston failed before the valves did-