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99 4.2 V6 running rough-again-I'm stumped!

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99 4.2 V6 running rough-again-I'm stumped!

 
  #1  
Old 08-27-2004, 03:02 PM
kbddbd
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99 4.2 V6 running rough-again-I'm stumped!

Hi - I did a search on rough running 4.2's and saw the threads about plugs, wires, motorcraft vs autolite, etc.... This is a bit different....

Mine started running rough about 25K ago, I replaced the wires and plugs and it ran well up until now. Its doing it again. I will say that I didnt use motorcraft parts (just autolite plugs and just a decent wire set) I know the EGR is OK, no vacuum leaks anywhere that I can find, and no codes in the computer (which is surprising because it runs so bad).

My question is; is it possible to wear these out in 25K miles? i dont run it very hard. I have run several tanks of gas to be sure it wasnt bad fuel. I am just completely stumped. This things runs like crap most of the time now.

I dont think its coil pack because its really only at low speed or idle (I have done the elect tests) Also - its a 99 and it doesnt seem to use coolant so I dont think I have the "leaking fords" problem. I am also a pretty experienced mechanic and none of the normal things seem to apply here.....

I am stumped and about ready to do a 2000 mile trip in a week. I am accepting any and all suggestions short of getting rid of it - Throw it at me! I need help!!! Maybe I need an exorcism ?????
 
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Old 08-27-2004, 03:33 PM
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Ken,
Like you, I'd like to think the plugs and or wires are not the problem. But, we musn't fail to see the forest for the trees.
You say plugs and wires solved the problem before. If it were me, I'd be inclined ot bite the bullet and spend $80 for new Motorcraft plugs and wires.
From bouncing around here at FTE, I seem to remember more than one occasion where guys have solved problems such as your with new plugs and wires.
It seems the general concensus is that if it is other than Motorcraft plugs and wires, it is open to suspicion. DOn't ask me why, but that seems to be the case.


You didn't mention the IAC assembly. Have you chacked that? it keeps your engine running while at idle and might explain the problem you describe.

Keep us posted!
 
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Old 08-27-2004, 04:50 PM
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Yeah - I read about the plugs and wires myth thing. I can understand all that and will give it a try. I was surprised when a wire set fixed the problem last time, maybe I will be surprised again? I hope so - I am really getting frustrated with this truck. It just seems to be very buggy this way. Lots of little problems but nothing that ever leaves you stranded.

I hate to say it but I have nothing good to say about either dealer that is local to me. I have a list the length of my arm (self included) that have been screwed by those guys. How they stay in business beats me. I generally drive about 40 miles to another town that has a very good dealership - will do that tomorrow and report back.
 
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Old 08-28-2004, 12:16 PM
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Replaced the wires and plug - runs good now -hmmm..

I replaced the wires and plugs - BTW at my local dealer,the wire set was 85.60 plus tax and the plugs were like 4.00 each. All told, the wires, plugs and a fuel filter were 153.00 - A little pricey but it was all motorcraft stuff.

The rough idle seems to have gone away _ am going to do some running around today and see how it holds up. I had used Bosch stuff before (plugs and wires) I guess it really doesnt like those. The myth might have proved to be true.
 
 
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