Misfire on Cylinder 4 | Ford Explorer Forums - Serious Explorations

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Misfire on Cylinder 4

REDDY

Active Member
Joined
May 18, 2009
Messages
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City, State
NY
Year, Model & Trim Level
99 Sport
99xpl sport 4.0 ohv

Runs rough, cylinder 4 keeps misfiring, new plugs, wires, coil, seafoam, fuel system cleaner, new fuel injector on 4, still runs rough, computer keeps reading cylinder 4 misfire.

80,000miles all original, dont know y it would be doing this

thinking about compression check, but shouldnt be dead with only 80,000

Any Help Please?
 



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Did you check the wires prior to installing? Also did you try another wire for #4?What did the #4 plug look like?
 






Did you check the wires prior to installing? Also did you try another wire for #4?What did the #4 plug look like?

all new wires, plugs, and coil, plug looked normal

hoping the computer aint doing this, well better than being a dead cylinder
 






Just because a wire is no does not insure that it is good.
 






Even with a new wire, it could be bad. But the chances of the old wire, and new wire both being bad on the same cylinder on not that great. Check compression (could just need a valve adj). Next I would check the injector. Use a mechanics stethoscope, or just a long screwdrive held up to your ear and listen to the injector. Compare it to the other injectors. If you do not hear anything the next step would be to build a noid light.
 






have you checked the coil pack
 






new coil, new injector, new plugs, new wires, and everything else i did i posted in the 1st box
 






Just because they are new does not mean they are good.

You MUST check them.
 






valve adjustment, is sounding more like the problem now, seems to make sense, valve could be stuck or loosened or somthing causing to do what it does after all the other stuff was replaced
 






valve adjustment, is sounding more like the problem now, seems to make sense, valve could be stuck or loosened or somthing causing to do what it does after all the other stuff was replaced

Then check the compression as suggested previously.
 






Just because they are new does not mean they are good.

You MUST check them.

there is no electrical sparks, arching or anything else going on with the wires

i dont blame for mentioning that just because its new doesnt mean anything, is very true countless times i bought new things for a vehicle and had to return becuse it was a factory defect or just didnt work
 






compression gonna be checked tomorrow or over the weekend, sore back now from working on it
 






if your not afraid of a little shock, then loosen the #4 plug wire so that it is almost coming off then, turn on the engine now lift the wire a bit and if you see or feel the spark then the problem might be the fuel injector for that cylinder good luck
 






if your not afraid of a little shock, then loosen the #4 plug wire so that it is almost coming off then, turn on the engine now lift the wire a bit and if you see or feel the spark then the problem might be the fuel injector for that cylinder good luck

thanks for helping but fuel injector was already replaced
 






You can build a noid light (comercial sets costs $40 ~ 50).

Noid light. Use a small 12 v light bulb, (a instrument panel light works well). Get 1” of 10 gauge solid wire, and 6” of 20 gauge stranded wire (or something close). Hammer the 10 gauge wire flat, and then cut it into two pieces. Take the 20 gauge wire and cut it into two pieces. Solder a wire to both leads of the light bulb. Then take the two pieces of flat wire and solder one to the other ends of the 20 gauge wire. Use heatshrink tubing to cover all exposed wires, except for ¼” of the flat 10 gauge.

You now have a homemade noid light. Plug it into the fuel injector harness . When you start the car, the light should flash, indicating that the ECM is trying to fire the injector.

This will give you a good indication if the ECM is functioning.
 






It is probably your DPFE.
The DPFE's go with old age and will cause a misfire read on cylinder 4. Happened to mine as well.
I would try that and see if it helps before messing with anything else expensive. Its a real easy fix and takes maybe 10-15 minutes to replace.
 






It is probably your DPFE.
The DPFE's go with old age and will cause a misfire read on cylinder 4. Happened to mine as well.
I would try that and see if it helps before messing with anything else expensive. Its a real easy fix and takes maybe 10-15 minutes to replace.

after searching this forum, this is what i got from explorers.....

most common causes of them, dpfe sensor and hoses around it, and lower intake gaskets, most common problems/fixs
 






on the dpfe sensor, on the hose towards the back of vehicle, not the one in front of it towards the front of vehicle, the inside of it is flaking, what line is that intake or return, if intake would make sense a piece got stuck in the dpfe sensor but if its return it should be blowing out and not sucking in the pieces to clog the dpfe sensor
 






My car is doing the exact same thing. I have done the same
fixes you have. (coil, plugs, wires....)

Did the DPFE sensor solve your problem?

I hope it isn't lower intake gasket as that it is a PIA to do.

-A
 



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My car is doing the exact same thing. I have done the same
fixes you have. (coil, plugs, wires....)

Did the DPFE sensor solve your problem?

I hope it isn't lower intake gasket as that it is a PIA to do.

-A

no it didnt fix the problem, new hoses it needed for sure, but no difference, have to do a compression check still, i might have to bring it to a garage, and i've like never had to do that before, but instead of buying all new stuff, pay the $50 to diagnose it with a better diagnostic machine to tell me what the problem is so i can fix it
 






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