Cop, good or bad?
Thread Starter
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Junior Member
Joined: May 2004
Posts: 7
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From: Seattle, Wa
Cop, good or bad?
Hey everybody, Someone tell me if I am getting this right or am I missing something. Can a coil be bad even if the ohm test shows it's good? I still have a rough idle on my '02 5.4 and the dealer has changed two coils because they read low on the range. Still have off idle. I think I will buy one new coil and start changing them until I find the bad one if that will work.
Thanks,
Thanks,
Technical Article Contributor
Joined: Jun 2002
Posts: 10,511
Likes: 10
From: Under the flightpath of old ORD 22R
Few things you might want to look at in addition to the coils.:
1. Check for VAC leaks that are letting in un-metered air. have seen this one more then once that the engine idles like crap, but it is not bad enough yet to cause a DTC to be set. Things like have you installed a FIPK as of late, or recently changed the air filter ( hoses to the intake tube, and corrected seating of the IAC ). Cracks on the common rubber boot for the PCV on the back of the T/B. Any other VAC lines that look to be cracking or have been pinched
2. IAC. This might be getting crapped up, and not opening all the way, causing a starving for air, and maybe causing the rough idle. Time to clean it maybe.
Just offering up a few other things that can cause rough idle, aside from COPs / plugs. Maybe looking a different direction is in order at the moment, if all the COPs are in range.
Good luck.
1. Check for VAC leaks that are letting in un-metered air. have seen this one more then once that the engine idles like crap, but it is not bad enough yet to cause a DTC to be set. Things like have you installed a FIPK as of late, or recently changed the air filter ( hoses to the intake tube, and corrected seating of the IAC ). Cracks on the common rubber boot for the PCV on the back of the T/B. Any other VAC lines that look to be cracking or have been pinched
2. IAC. This might be getting crapped up, and not opening all the way, causing a starving for air, and maybe causing the rough idle. Time to clean it maybe.
Just offering up a few other things that can cause rough idle, aside from COPs / plugs. Maybe looking a different direction is in order at the moment, if all the COPs are in range.
Good luck.