Engine misfiring

FORD4X4250

MEMBER
1989 FORD FIVE HUNDRED
128,000 MILES

My 1989 ford f250 efi 460 motor was running great then I moved the negative battery cable to a better spot other than on the factory mount on the exhaust manifold, now it runs very rough, misses badly and barely runs. What did I do wrong? Or is there something else? I have previously replaced the plugs, cap, rotor and wires, battery is new also.

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CARADIODOC

MECHANIC
33,864 POSTS

What's the question / symptom / problem?

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Sunday, October 2nd, 2011 AT 4:08 AM

FORD4X4250

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I already asked the question I need an answer please, why does my motor miss fire after messing with the negative battery cable? How can I solve the problem?

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Sunday, October 2nd, 2011 AT 5:36 AM

CARADIODOC

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I'm really confused. Did you replace all those parts to solve the misfire, or did the misfire start after you replaced them? Where is the negative battery cable bolted to? There should be two; the fat one goes to the engine block and the smaller one bolts to the body.

If you asked a question previously, you should continue that thread with the person who replied. That way they will get an automated e-mail directing them back to it when you post an update. They will often not see it when you start a new one.

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Sunday, October 2nd, 2011 AT 7:43 AM

FORD4X4250

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No sorry I'm a first timer to this site. Let me start over. My truck was running fine / smooth idle, I wanted to move the negative / ground battery cable from the exhaust manifold (factory location) because it is a bad spot cause it gets to hot and it rust easy OK, so I moved it to a clean rust free location on the intake manifold, then I started my truck and now it will barely run, misfires and very rough running, in a nut shell it ran good then after messing with the ground battery cable it runs very rough and misfires, did I mess up something or can it be reset or fixed? Thanks

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Sunday, October 2nd, 2011 AT 8:01 AM

CARADIODOC

MECHANIC
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That location should be fine. If there was a problem with that cable, the starter wouldn't even crank the engine. Since the starter works, you know the negative battery cable on the intake manifold is okay.

Start by looking in the areas you were working to see if a sensor became unplugged, a vacuum hose got cracked or disconnected, or anything like that. Double-check the spark plug wires to be sure they're in the right order. Check for air leaks in the fresh air tube between the mass air flow sensor and the throttle body. Any air that sneaks in that isn't measured won't get any fuel to go with it.

If you still haven't found the problem, try returning the negative cable to where it was bolted before. I suspect it will still run poorly, but at least that will prove the cable's location isn't the cause of the problem. If it DOES run better, that would be weird, but then I'd be looking for a rusted-off ground strap between the engine and body.