Engine has miss
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Mountain Pass
Joined: May 2003
Posts: 107
Likes: 1
Engine has miss
My engine has the weirdest time with a miss problem. Some days it will miss when accelerating, some days it will not miss a beat. It will run very smooth when in park or neutral. As soon as you put it in gear you can hear it start to miss again. I have recently replaced the spark plugs and wires and also the cam pos. sensor. I have not really seen it miss differently whether the temp or rain makes a difference. I guess my question is: What is the best way to find the missfiring COP? Could the crank sensor be doing this? The pcm has not given a trouble code yet and it has been doing this for at least 3 months now. Can I start the truck up and unplug a COP at a time to find it or will that screw up the pcm? I had a heck of a time replacing all the plugs especially the two at the rear passenger side. Any ideas?
BTW I have a '99 F250 w/V10, 4x4, about 106k miles.
BTW I have a '99 F250 w/V10, 4x4, about 106k miles.
Last edited by theswagg; Nov 9, 2006 at 06:32 AM.
Posting Guru
Joined: Jul 2006
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From: New York
Originally Posted by theswagg
My engine has the weirdest time with a miss problem. Some days it will miss when accelerating, some days it will not miss a beat. It will run very smooth when in park or neutral. As soon as you put it in gear you can hear it start to miss again. I have recently replaced the spark plugs and wires and also the cam pos. sensor. I have not really seen it miss differently whether the temp or rain makes a difference. I guess my question is: What is the best way to find the missfiring COP? Could the crank sensor be doing this? The pcm has not given a trouble code yet and it has been doing this for at least 3 months now. Can I start the truck up and unplug a COP at a time to find it or will that screw up the pcm? I had a heck of a time replacing all the plugs especially the two at the rear passenger side. Any ideas?
BTW I have a '99 F250 w/V10, 4x4, about 106k miles.
BTW I have a '99 F250 w/V10, 4x4, about 106k miles.
Post Fiend
Joined: Jun 2003
Posts: 5,643
Likes: 8
From: NE Texas
You said you changed the plugs and "wires". Did you mean the boots? In my opinion you should replace the boots at the first plug change, at least. All of them.
In order to chase down the bad COP (if the boots are not the problem), then you would need to buy a new COP and just go down the line. However, if you don't have a COP that has totally failed, which sounds like your case, it might turn into a nightmare.
I know the cost varies, but taking your truck to a dealer and letting the tech do a diagnostic test really saves time. The cost could be as little as $50 and as high as $100, FYI
In order to chase down the bad COP (if the boots are not the problem), then you would need to buy a new COP and just go down the line. However, if you don't have a COP that has totally failed, which sounds like your case, it might turn into a nightmare.
I know the cost varies, but taking your truck to a dealer and letting the tech do a diagnostic test really saves time. The cost could be as little as $50 and as high as $100, FYI
Thread Starter
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Mountain Pass
Joined: May 2003
Posts: 107
Likes: 1
I went ahead and bought a COP at Autozone while I was near one. They are only $50 for one with a boot already on it. So tonight I will start to replace each one and see how things go till I find the bad one. I do believe it is on the passenger side though. I do remember one of the cops having a darkened coil tab on it, not shiny like the others. I wish I had put it in a specific place though. My local Ford dealer is so slow, I hate to take anything there. I wish it would give me a trouble code to make things easier but oh well.
Junior User
Joined: Dec 2004
Posts: 58
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my 99 F250 5.4 had the same problem. It was the first cop on the drivers side.
The dealer could not find the problem. I just purchased one cop and replaced the first one behind the rad on the driver's side. If you spray some water on one cop and then take for a drive. this will show you which one is bad
The dealer could not find the problem. I just purchased one cop and replaced the first one behind the rad on the driver's side. If you spray some water on one cop and then take for a drive. this will show you which one is bad
