problem with 1990 5.0 - Ford Mustang Forum
 
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post #1 of 9 (permalink) Old 09-06-2015 Thread Starter
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problem with 1990 5.0

been a while since i posted here but ive had my car in storage. anyway the car starts, runs, and idles fine so i took her for a ride, all seemed normal until i shifted into 2nd gear she started misfiring then popped (which sounded like a backfire) then ran fine again. she does this every time the engine is cold. i put fresh gas in her thinking maybe the gas was making here run like s*** i drove the piss out of her yesterday to run the old gas out and still no change, i pulled the spark plugs and found brownish white on the tip which i thought was normal. i checked the timing and was 10* BTDC. i then replaced the TPS for other reasons too but i was hopeful lol. anyway the car runs better when warmed up until let off the gas then floor it she misfires until a pop can be heard then runs fine again. anybody have any other suggestions? she had all new plugs/wires/cap/rotor last year so i doubt thats anything


1990 Ford Mustang GT Convertible 5 speed AKA Stacy-Dynomax Ultra-flo catback exhaust
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post #2 of 9 (permalink) Old 09-07-2015
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do you still have the original cats on it? those might be messed up from sitting in storage or the o2 sensors as well. how long in storage?

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post #3 of 9 (permalink) Old 09-07-2015
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My 2 guesses would be pour a can of BG44K in the gas tank. That works for a lot of things! How many miles do you have on it? 'Seems like I replace my ignition module on the dist. about every 60K. Good luck, let us know..
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post #4 of 9 (permalink) Old 09-07-2015 Thread Starter
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Originally Posted by whitemare View Post
do you still have the original cats on it? those might be messed up from sitting in storage or the o2 sensors as well. how long in storage?
yes on the cats. and she has been sitting in storage untouched for about 3-4 months. i did put a new 02 on the driver side last year, is there one on passenger side also?

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Originally Posted by GPa's GT View Post
My 2 guesses would be pour a can of BG44K in the gas tank. That works for a lot of things! How many miles do you have on it? 'Seems like I replace my ignition module on the dist. about every 60K. Good luck, let us know..
ill the that stuff, the car has about 135k on it are you referring to the TFI module? cause i read those are expensive as hell

1990 Ford Mustang GT Convertible 5 speed AKA Stacy-Dynomax Ultra-flo catback exhaust
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post #5 of 9 (permalink) Old 09-08-2015 Thread Starter
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bump...any other suggestions? im running the fuel system cleaner through now but its not looking like it will help. what about the TFI?

1990 Ford Mustang GT Convertible 5 speed AKA Stacy-Dynomax Ultra-flo catback exhaust
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post #6 of 9 (permalink) Old 09-08-2015
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Drive it again and watch the tach, preferably in a higher gear. If you are fully in a gear, the engine speed cannot change that rapidly. If the tach needle jumps around when the engine misfires, I would be looking at the low voltage side of the ignition system (TFI module, wiring, dizzy). If the tack does not bounce when misfiring, then it's air/fuel related (MAF sensor, bad injector, etc.) or high voltage side of ignition (plugs, wires, coil).

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post #7 of 9 (permalink) Old 09-08-2015 Thread Starter
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i just took her for a ride and seems the symptom disappeared, i drove her all over and beat the piss out of her and i could not duplicate the issue but its preey hot out today im gonna try it again in the morning when its cooler and see if ambient temperature affects her...i tried to check the fuel pressure but i cannot find my damn Ford fuel line adapter for my tester seems every time i need a tool its never where its supposed to be . but i did run codes both KOEO and KOER both tests gave mw 11 which is system pass

1990 Ford Mustang GT Convertible 5 speed AKA Stacy-Dynomax Ultra-flo catback exhaust
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post #8 of 9 (permalink) Old 09-08-2015
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injector?

Maybe a leaky injector? causing a second detonation at intake stroke...
Maybe just give it some time, and if not, throw a bottle of injector cleaner in there..

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Classic Volvo enthusiast & owner of 1989 5.0 LX notchback
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post #9 of 9 (permalink) Old 09-09-2015
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there should be one on the passenger side too. I always change both at the same time, if u have on dirty and one clean I can't imagine the computer reading those correctly. 3-4 months isn't bad, next time start once a week, I had to keep mine "stored" but tried to start it once a week or so just to keep everything going. Got it legal in june so far no problem.
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