Idle only miss
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Idle only miss
2001 Excursion V10. New engine about 30k (initially put 3k on accident) miles ago. All COPs replaced at that time. Went to hook up the trailer last weekend and noticed a consistent miss only at idle. Has plenty of power, pulled a trailer to put a load on it and couldn't replicate the miss off idle. As soon as it's back to idle it has a consistent miss hot or cold.
Noticed the PCV hose that has insulation wrapped around it doesn't look to be in the best of shape, so ordered one from the local Ford dealer and it'll be here Thursday.
In the meantime, any other common causes of a miss at idle? No check engine light or codes.
Noticed the PCV hose that has insulation wrapped around it doesn't look to be in the best of shape, so ordered one from the local Ford dealer and it'll be here Thursday.
In the meantime, any other common causes of a miss at idle? No check engine light or codes.
Laughing Gas
Joined: May 2011
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From: SoCal
It’s really hard to diagnose these trucks without the help of a scanner. There are so many things that are interdependent that could cause a miss. I’m assuming you have replaced plugs and cops with the new engine. Could be a bad connector (injector or cop). I doubt it’s fuel related because it only occurs at idle. A scanner may not even help if the miss doesn’t exceed the threshold. Then again if you have not replaced coils and plugs it might be a good place to start. Sorry not much help.
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Thanks, going to take it to a shop and see if anything shows up on the scanner. Only other way I can think of is to replace each COP and boot one at a time and see if it clears up. We did have more humid weather and then rain, and from what I've read that could be associated with a cracked boot. Just strange that it only misses at idle and no noticeable shaking or power loss once moving.
Fleet Mechanic
Joined: Mar 2019
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Thanks, going to take it to a shop and see if anything shows up on the scanner. Only other way I can think of is to replace each COP and boot one at a time and see if it clears up. We did have more humid weather and then rain, and from what I've read that could be associated with a cracked boot. Just strange that it only misses at idle and no noticeable shaking or power loss once moving.
Fleet Mechanic
Joined: Oct 2012
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I had a miss that seemed to only appear at idle. First time I noticed it was after towing my camper for the first time. Mine did eventually throw a code.
When I examined the COPs I noticed the clips holding the plugs on them were broken. I unplugged each one, cleaned them with electrical contact cleaner and then sprayed them with di-electric. I haven't had an issue since.
I think Forscan can tell you which cylinder is missing. The regular code reader only told me that a cylinder was.
When I examined the COPs I noticed the clips holding the plugs on them were broken. I unplugged each one, cleaned them with electrical contact cleaner and then sprayed them with di-electric. I haven't had an issue since.
I think Forscan can tell you which cylinder is missing. The regular code reader only told me that a cylinder was.
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Turned out to be the boot on #10. Used the torque app with a cheap OBD Bluetooth reader to see which cylinder was having issues. #10 was right below the limit of throwing a code according to the app. Replaced the boot and it smoothed right out.
Resting my hand on the extended tow mirror I can feel a real slight miss and #4 and #6 showed a low misfire count, so I'll go ahead and replace those boots as well. Also replaced the PCV and associated hoses as they looked to be in poor condition, but that was after the main miss was corrected.
Resting my hand on the extended tow mirror I can feel a real slight miss and #4 and #6 showed a low misfire count, so I'll go ahead and replace those boots as well. Also replaced the PCV and associated hoses as they looked to be in poor condition, but that was after the main miss was corrected.
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Joined: Jul 2010
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From: Media PA
Turned out to be the boot on #10. Used the torque app with a cheap OBD Bluetooth reader to see which cylinder was having issues. #10 was right below the limit of throwing a code according to the app. Replaced the boot and it smoothed right out.
Resting my hand on the extended tow mirror I can feel a real slight miss and #4 and #6 showed a low misfire count, so I'll go ahead and replace those boots as well. Also replaced the PCV and associated hoses as they looked to be in poor condition, but that was after the main miss was corrected.
Resting my hand on the extended tow mirror I can feel a real slight miss and #4 and #6 showed a low misfire count, so I'll go ahead and replace those boots as well. Also replaced the PCV and associated hoses as they looked to be in poor condition, but that was after the main miss was corrected.
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The boot didn't look particularly bad, no visible cracks however the new boot made an instant change to smoothing out the idle. No more misfire unless I'm really feeling for it. Like I said only noticeable with the tow mirrors full extended and resting my had on it can I feel a slight vibration out of normal in the idle.
The PCV hose didn't look bad except the insulation around it was cracking and I didn't want it to make a mess, so replaced it. Taking it off it was pretty oil saturated and the boot at the end was quite frail.
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