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Engine Missing with high idle

Old Feb 2, 2015 | 09:12 PM
  #1  
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Lance Helmert
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Engine Missing with high idle

When my EX is idling it idles at a little over 1000 rpms and then revs up to anywhere between 1500 and 2000. And then idles back to 1000 and continues this cycle. Usually it idles below 1000 rpms. There a miss at cruising speed and sometimes at idle. It did it a week or two ago, filled up with gas and went to put it on the scanner and of course it ran fine. Thought it was maybe a fuel issue so I put a bunch of the Chevron injector cleaner in the tank and went through a tank of gas so far. It ran good up until this week and now it is back to doing the same thing. Took it to a mechanic who suggested we try new plugs and fuel filter. He said there are tiny cracks on the tops of the COPS but he doesn't think this is the problem, they are just weather checked. On the way to the shop it ran fine again but when the mechanic took it for a ride he said he could feel a miss at cruising speed but was not doing the weird stuff at idle. Because it isn't happening right now he is having a hard time diagnosing the problem. Any ideas on what is going on?
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Old Feb 2, 2015 | 10:07 PM
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Moving this to the V10 forum, don't know too much about the V10, but cracked COPs sound suspect to me.
 
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Old Feb 3, 2015 | 12:41 AM
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A couple things I would try are a mild tune up including a fuel filter and a pcv valve. Check the elbow hose under the throttle body which connects to the PCV, these are common failure points. It may be a good time for new plugs as well. What maintenance has been done since you have had it?
 
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