89 fox body will not run right.

Asked by Sep 24, 2013 at 09:24 PM about the 1989 Ford Mustang GT Convertible

Question type: Maintenance & Repair

my 89 fox body idles right and runs right until it gets above 2 grand then it sounds like it is backfiring and looses all power I have had 3 people set the timing including one guy who restabbed the distributor, which really helped, but it still wont run right. what could my problem be? btw the  car has a b303 cam.

25 Answers


You could have a distributor pickup coil or ignition module going bad, have you had them checked?


Also you can check the codes, this article will show you how.... http://www.stangnet.com/mustang-forums/threads/help-me-create-the-surging-idle-checklist.698148/

list of new parts are as follows spark plugs and wires, ignition module, cap and rotor, battery, and oxygen sensors

oh and new pcm


I didn't see a distributor pick up coil listed, it might be a good idea to have the engine hooked up to a scope so someone could see the ignition pattern as RPM's increase.

1 out of 1 people think this is helpful.

ok sounds like a plan not having hooked a scope up to such an old vehicle how do I do it?


well you have to take it to a shop and have them do it unless you have a 10,000 scope in your garage


I meant a $10,000 doller scope in your garage


sounds like the coil breaking down.


Mine did the same.was a bad distributor

i have access to a modus, and are you talking about the coil mounted on the fender or the stator in the distributor



ok thought so


i was speaking of the external coil.

ok so how do I test it with the modus

the pick up coil


Did anyone think to unplug the SPOUT connector before setting the timing? If so, the E-coil breaking down is a logical guess but the correct method to diag this one is with an oscilloscope and an old-timer that knows how to read it.

yes the spout was unplugged but the question is how do I hook up the o-scope to test the pick up coil


Number 1 spark lead on number 1 spark plug wire, coil lead on coil wire, if your scope is old then you will have a dwell wire and that will need to be hooked up with the coil negative wire. If you know how to read a scope pattern then it will be obvious to you when the RPM's climb you will see the dwell pattern diminish and the engine will start to run poorly, you can also see the coil output on the screen.

ok went ahead and replaced the distributor but it is still stutters. i did find out that one of the coolant temp sensors was out replaced it but the car still stutters. oh forgot to say the car used to be an 87 but now has maf


so its a 1987 with a 1989 engine?


you are best off to bring it in and have it scoped other wise you are going to through money aftr money at it and find out it was something simple that every one of us are over looking. I am a back yard mechanic my self and some times you need the right equipment to figure stuff out

yes it is an 87 with an 89 comp and yeah took it to a 80 model tech so he can check the computer and everything


It may cost you some money but it may end up being cheaper in the long run. Hope every thing works out for you

ok figured out the problem it was very small pieces of rust clogging the pressure line plus it was clogging the fuel pump bought a new fuel tank and pump and the problem went away thanks for the ideas

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