Missfire over Half Throttle?
 

Hi guys, I need some help, My 89 GT 5 speed has developed a missfire over half throttle. If I accelerate slowly it seems to be ok. Its not rpm related either, same deal if I accelerate slow she will rev smooth all the way. I checked cap, rotor,wires, put in new plugs, but no change. I ran the tps through full range with a meter on but no indication of short or open cct, no codes from the computer either. She dosn't have O2 sensors or cats cos the car is in Saudi Arabia. Thanks

Chris Schulz

Here lately a few of us have had this problem. For at least three of us it has worked out to be a faulty distributor. I am not sure which part of it though, I just changed the whole thing.

Make sure the plug wires going to #5 & #6 are completely separated from each other, from the cap to the plugs.

Take care,
~Chris

Thanks guys, I'll try that. It will take a while to get another dizzy as I am out in the middle of nowhere here. I'll let you know what happens. Cheers
Chris

Thanks guys, I'll try that. It will take a while to get another dizzy as I am out in the middle of nowhere here. I'll let you know what happens. Cheers
Chris

I'd be willing to bet on a fuel pump and/or regulator.

Is it really a "misfire" or just leaning out? That's what I'd want to know. Read the plugs to get an idea. Still betting on the fuel pump/regulator, though. Hope not for your sake, FWIW!

i have heard this same problem about 20 times. i have had the problem on 3 of my stangs and 2 of my buddies have. most likely the culprit is a bad mass air meter (sensor). this has been the fix for all that i have heard having this problem. if you know someone with a stang, just switch their sensor out and see if thats it.

I have had a on going 2000 rpm missing problem.Never above or below that rpm on my 89.replaced plugs wire's cap rotor and it did it before all this and it is still doing it, if not getting worse.Changed the fuel filter also.Could it be the tfi module?

COIL OR MASS AIR SENSOR

LOL yup./... check the damn coil... you might remember the post "odd" I had running for months about that.


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