1994 Mustang GT 5.0 check engine light and timing problems - Ford Mustang Forum

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post #1 of 4 (permalink) Old 05-02-2008 Thread Starter
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1994 Mustang GT 5.0 check engine light and timing problems

Ok so ill start this off saying, i dont know that much about cars cuz im still a kid so im still learning.
Anywaysm, my problem is I have changed my plugs and wires but i still have hirrible gas mileage. I am averaging 12MPGS(with a light foot).
And what i am trying to get at is i need to learn how to do my timing i know it should be set from12-14 and stock is 10 but i need to know how to do this step by step.

my other problem is i have a check engine light that goes on periodically. when i first start my car its gone but sometimes when i jump on it, it goes on or just randomly does. i hooked up a code reader but it didnt pull up a code. what could be wrong?

any help would be greatly appreciated.


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post #2 of 4 (permalink) Old 05-02-2008
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When you replaced your plug wires, did you install them one by one and in the exact same spot on the distributor as the ones you took off? It sounds like your firing order (the order each cylinder fires in as directed by the distributor) is off. See the diagram I attached to this and make sure your wires match it. The numbers correspond to the cylinder number. For this part you'll need a timing light which you can get at any auto parts store. Drive your car a good 15-20 min to get it at full operating temperature. Next, loosen the bolt holding the distributor in place and unplug the spout connector (the gray fuse looking thing on the distributor wire its about half way down the distributor, its a small cluster of electrical wires). Connect the timing light + and - to the battery then clip the last wire onto the #1 spark plug wire. Start your motor, aim the light down at the crankshaft pulley and carefully rotate your distributor until it's at 12 degrees (that's the timing advance). Turn off your motor, tighten down the distributor bolt and start your engine again to make sure the timing mark is the same and you didn't bump it off when tightening the bolt. Motor off again, disconnect the timing light and plug the distributor spout back into the distributor's electrical wiring and go for a drive. If your engine feels a little off, do the same thing again and try advancing the timing a little more (rotating the distributor clockwise) to 14. Play with it until you get the smoothest performance from your engine. This should also get rid of the "Check Engine" issue. Your engine is either misfiring or the knock sensor is throwing the check engine light because the timing is off and its running rough.

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1984 Mustang 331 stroker
1990 Mustang 5.0L convertible
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post #3 of 4 (permalink) Old 05-02-2008
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He explained how to reset the timing, do that and see if it helps. That CEL could be different things, though.

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post #4 of 4 (permalink) Old 05-02-2008
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I agree with EagleAutoSports about the check engine light. If after you finish with setting the correct timing the check engine light still comes on, pull the engine codes. Head over to you local auto parts store and get a code reader. Some stores like Auto Zone will let you borrow one to use in their parking lot. See what comes up on the reader and make the necessary repair if you know how or search the forums here for assistance, we're happy to help.

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