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Gear head
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Discussion Starter #1
I was wondering if anyone has any idea what might be wrong with my engine the only code that the computer sees is a #2 cyl missfire. pulled the coil and plug out all fine. plugs were replaced at 98,000. I have replaced the #2 coil and # 5 coil at that time now my engine has 139,600 miles on it. THe engine only hesitates or misses badly under load or under acceleration. very poor gas milage. Temp does not affect this problem at all. changed the fuel filter checked the air filter checked and measered the maf sensor ohms checked the tps sprayed carb & choke cleaner around all intake gaskets. THe only problem is, is that it soes not do this all the time but it does it most of the time. PLEASE HELP! I don't have much hair left on my head
 

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Have you checked the electrical connection at the #2 injector and the #2 coil? A bad/loose connection at the coil or injector will cause an intermittent misfire like you're describing. Visually inspect the wires at the connections to be sure there aren't any broken or partially exposed wires. I would tell you to check the plug wires...but there are none!

Crankshaft position sensor could also be the culprit, but the computer should tell you if it was the problem. In addition, the misfire would occur on some/all of the cylinders randomly so I would guess you have a simple electrical problem.

Good luck.

Brian
 

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Gear head
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7 Posts
Discussion Starter #3
I have already checked all the wire conections @ the injectors and even went as far as replacing the coil just to make sure that it was not the problem. I am going to try and replace the TPS next. I have even stumpt every mechinic that I have talked to about this problem, because I have checked and tested everything that they would have checked themselves. I even followed the flow chart in the service CD that I got from FoMoCo. Could an injector cause this problem as I have described? If the TPS doesn't work I will have to try this next.
 

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The injector itself definitely could be the culprit. A good way to know for sure is to swap the #2 injector with an injector from another cylinder, clear the codes, and drive it for a while. Once the misfiring starts again, pull the codes. If the misfire is still at the #2 cylinder, you know the injector isn't the problem. Saves you from buying an injector if you don't need one. Just be sure to relieve the fuel pressure before removing the fuel rail!

I would be very surprised if the TPS is the culprit but electrical systems can definitely do some weird stuff. A good example of this is having a brake light out on a vehicle with the E4OD tranny can cause erratic gear shifts. The electrical gremlins can be tough to catch.

Hope you find the trouble.

Brian
 

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You may want to swap a coil too. I had #2 coil replaced under warranty and it went out a week or so later.....replaced again and no problems since. Ford has had problems with coils on truck engines.
 

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Ranger Member
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10 Posts
Sounds like a bad spark plug boot to me. If it had wires you could rev it up in the dark and see the 'leakage' but I bet you have one or more boots that are arcing to the cylinder head.
 

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I have to agree with hotrodford when you replace the plugs its good to replace the boots also. My shop usally gets them from any parts store .
 

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97 F-150 XL 4x4
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799 Posts
i have come across a missfire problem or 2 and sometimes find that all it takes is a pair of pliers to pinch the rubber boot on the plug end of your wires so that when you push it onto the plug you get a nice tight connection !
this has cleared up more than one missfire problem for me in the past and it doesnt hurt to apply a little dielectric grease inside the plug boots either.
 

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97 F-150 XL 4x4
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799 Posts
can you switch 2 of the wires and see if the problem follows the wire change or stays on #2 cyl.
i dunno how the ignition is setup on those 5.4's i never seen one but my 4.2 had a miss so i pulled 2 wires off the coil and plug and then switched them and it stayed on the same cyl so all i did was replace that plug and the problem was gone.
my setup uses a seperate coil for each cyl.
 

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No wires on the modular engines!! It's simply one coil per cylinder directly above the spark plug in the top of the head.....not on the side near the exhaust manifold like most earlier model engines. The coil plugs directly into the wiring harness and gets a signal to "spark" from the computer via the crankshaft position sensor and pre-programmed timing curve. It's simply a mini coil with a small boot that slides over the end of the spark plug.....that's it. No distributor either.
 

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97 F-150 XL 4x4
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799 Posts
i see that doesnt leave much for the average backyard mechanic to work with does it.
in this case i guess it would be best to keep an extra coil on hand just for this type of problem.
 
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