OT Coils OT

[P-12 Tommy]

Hey guys, I changed out all the coils and spark plugs on my girlfriends 2002 Lincoln Navigator two months ago. The car was running fantastic then all of a sudden I've got a coil going bad already. Does anybody know the easiest way to determine which coil is screwing up? Service engine soon light is NOT coming on. So I can't bring up any codes on my code reader. I've been on the Internet the last few days and can't come up with anything. I'm sorry I know it's a Ferd product:o and I figured maybe somebody here has been through this before.

Tom

[Young Ed]

Is it running badly at idle or speed? Got any of the old coils still? Swap one at a time until its fixed. Check the plugs too. Dads 2000 GMC had a heck of an issue with running rough at highway speeds that turned out to be a defective spark plug.

[P-12 Tommy]

Is it running badly at idle or speed? Got any of the old coils still? Swap one at a time until its fixed. Check the plugs too. Dads 2000 GMC had a heck of an issue with running rough at highway speeds that turned out to be a defective spark plug.

It's starting to run rough ideling and driving. I thought maybe there was an easier way. I won't have a break 'till the first of the month. It's just so time consuming to pull them one at a time.

Tom

[Adam H P15 D30]

Is it a 32 valve 5.4L? They have problems with exhaust valve seat going bad. BIG $$$$$$$! Some have warranty extensions on injectors leaking, much more common. Send me the VIN and I will run it and see. I've seen these injectors take out a whole engine.

Oh, by the way, you didn't put Bosch or split fire plugs in it when you changed the coils did you?

Adam

[greg g]

The standard trouble shooting procedure for finding a missfiring cylider was to disable the ignition to one spark plug at a time. This this would make the engine miss worse when a good plug, wire, coil, etc was removed from the running engine, when you got to the one that was missing, the running condition would not change when the bad cylinder was encountered. This may not tell you what component is at fault but would at least isolate the cylinder that is missfiring.

[P-12 Tommy]

Within an hour after posting I went to get lunch and the "Service engine soon" light came on. Now I can check the code or codes when I get home.

Tom

[P-12 Tommy]

Is it a 32 valve 5.4L? They have problems with exhaust valve seat going bad. BIG $$$$$$$! Some have warranty extensions on injectors leaking, much more common. Send me the VIN and I will run it and see. I've seen these injectors take out a whole engine.

Oh, by the way, you didn't put Bosch or split fire plugs in it when you changed the coils did you?

Adam

Adam, I put in Motorcraft plugs. Here's the VIN#5LMEU27R12LJ06025

Thanks, Tom

[P-12 Tommy]

The standard trouble shooting procedure for finding a missfiring cylider was to disable the ignition to one spark plug at a time. This this would make the engine miss worse when a good plug, wire, coil, etc was removed from the running engine, when you got to the one that was missing, the running condition would not change when the bad cylinder was encountered. This may not tell you what component is at fault but would at least isolate the cylinder that is missfiring.

Greg, That's what I normally do but I don't have alot of time to work on this, so I was looking for a short cut.

Thanks, Tom

[P-12 Tommy]

Is it running badly at idle or speed? Got any of the old coils still? Swap one at a time until its fixed. Check the plugs too. Dads 2000 GMC had a heck of an issue with running rough at highway speeds that turned out to be a defective spark plug.

Ed, I always keep the old stuff just in case I need something.

Thanks, Tom

[Adam H P15 D30]

Within an hour after posting I went to get lunch and the "Service engine soon" light came on. Now I can check the code or codes when I get home.

Tom

Tom,

You don't have the extended warranty on injectors Find out which cylinder it is and do a compression check on that cylinder and the one next to it. DO NOT CLEAR THE CODE.... Also, how many miles are on it??? If all looks good, swap coil with another cylinder and see if the missfire moves. Did the coils come with new boots? If not replace all the boots. Also check and make sure no oil is leaking from the valve cover seals into the spark plug holes, they should be completly dry. FYI the computer will shut the injector down for that cylinder when it detects a missfire. If the missfire does NOT move when you move the coil its 1) harness problem 2) PCM driver or 3) low compression caused by a bad exhaust valve. let me know what you come up with.

BTW if you unplug a coil to see if the cylinder drops, the PCM will turn that injector off to save your CATS, so you can't use that test on these vehicles. Works great on our flatheads though.

Edited September 17, 2010 by Adam H P15 D30

[P-12 Tommy]

Tom,

You don't have the extended warranty on injectors Find out which cylinder it is and do a compression check on that cylinder and the one next to it. DO NOT CLEAR THE CODE.... Also, how many miles are on it??? If all looks good, swap coil with another cylinder and see if the missfire moves. Did the coils come with new boots? If not replace all the boots. Also check and make sure no oil is leaking from the valve cover seals into the spark plug holes, they should be completly dry. FYI the computer will shut the injector down for that cylinder when it detects a missfire. If the missfire does NOT move when you move the coil its 1) harness problem 2) PCM driver or 3) low compression caused by a bad exhaust valve. let me know what you come up with.

Adam, Thanks for your responces. I'll let you know.

Tom

[P-12 Tommy]

Well, I got home and checked for a code and came up with PO302. No#2 cylinder missfire. I changed the coil and alls well. The funny thing is, the last time I had a bad coil, the light never came on. Hmmmm. Thanks for all your suggestions.

Tom

[Adam H P15 D30]

Well, I got home and checked for a code and came up with PO302. No#2 cylinder missfire. I changed the coil and alls well. The funny thing is, the last time I had a bad coil, the light never came on. Hmmmm. Thanks for all your suggestions.

Tom

At least it's an easier cylinder to get to. Any oil on the boot?

Edited September 17, 2010 by Adam H P15 D30

[P-12 Tommy]

At least it's an easier cylinder to get to. Any oil on the boot?

Nope.

Tom