Miss at idle?

[Greg S]

My 2002 T Bird has developed a miss at idle. may be present when moving but not very noticeable. I'm not getting any problem codes on the dash. The COPS and plugs are original and now have 75,000 miles on them. I'm thinking one or more COPS. What do others here think. IF a COP, should all be replaced or just the offending COP(s)?

[StevenM]

My money is on a bad COP...ignition coil type! I’d replace them all. A deal now on eBay has some inexpensive coils at $45 for a set of eight. You can also buy much more expensive coils too. Can’t tell if quality and price are related. While doing the coil change, do spark plugs as well. At 75K miles, I’m certain both need changing. If you have a small degree of mechanics and a few tools, this job can be a do it yourself. Good luck.

[wcoates]

My money is on a bad COP...ignition coil type! I’d replace them all. A deal now on eBay has some inexpensive coils at $45 for a set of eight. You can also buy much more expensive coils too. Can’t tell if quality and price are related. While doing the coil change, do spark plugs as well. At 75K miles, I’m certain both need changing. If you have a small degree of mechanics and a few tools, this job can be a do it yourself. Good luck.

I agree with Steve. At 75000 miles I'd replace them all. Here is the list of tools that our friend Bill Green has provided that he has used to change more than one set in parking lots in more than one state.


Originally posted by 15AGAIN View Post

List of tools I have in the trunk for coil and plug replacement
• 3/8 ratchet
• 24 “ 3/8 extension
• 12” ¼ extension
• ¼ drive,7 mm swivel socket
• 3/8 to ¼ adapter
• 3/8 drive 5/8 spark plug socket
• 3/8 drive swivel
• ¼ “socket set
• Anti Seize Lube
• Dielectric compound

[Greg S]

Thanks guys, appreciate your opinions. So you don't think I should bother with a scan, just change all eight cops and plugs?

[StevenM]

Thanks guys, appreciate your opinions. So you don't think I should bother with a scan, just change all eight cops and plugs?

Greg, just like you my 110K mile car developed a miss, especially increasing speed and going up hill. No light on the dash to indicate any issue. I do have an OBD scanner and checked for codes. I showed a code for a bad ignition coil (can't remember the actual number) and as luck would have it, it was the number 8 coil, the most cantankerous one to get to....thus the remaining 7 and all 8 plugs changed. The list of items Bill provided is pretty complete. I did make a visit to my local Harbor Freight and picked up a set of ratchets similar in size and shape as a 50 cent piece. Proved very useful, with the 7mm socket, in removing the PITA fasteners holding the COP covers in place. I will also suggest being a little less aggressive disconnecting the wire harness from the COP. Like mine, yours might be brittle from age and heat and will easily break the locking tab. Use the anti seize on the plug threads and dialectic grease on the plug connection and on the COP wire connection. Again...good luck. If you have an Auto Zone, Pep Boys, O’Reilly Auto Parts, I’ll bet they will run a code reader for you at no cost.

[Greg S]

Thanks for the response Steven.

[Gobird]

I agree with the coils. Mine started doing this at about the same mileage as yours and at 80,000 miles I replaced all the coils and plugs at the same time. I now have over 125,000 on the clock and no problems.

[Jimr]

At 75,000 miles if it isn't coils it surely is plugs. Change them both.

[Fuchsaudio]

On this same subject; So let me ask; I have a 120-k Bird and have a nasty miss at certain combination of speeds and rpm's especially under a bit of a load (uphill). About 2-k/60 mph. The car actually vibrates and lunges like it's about to stall.

Idle is smooth. Revving while standing in park, smooth, codes clear. Cops and plugs have 5-k or so on them as do dual cats. My mechanic thought it was a vacuum hose leak, but that didn't fix it. There is a slight putt-putt sound at idle by tailpipes, muffler bad ?? It's still got tons of pickup and if you get above the roughness or downshift it goes away. 50-100 mph is still a hoot.... help ?

I am am buying a code reader that speaks to my I-phone so I can get realtime readout, but in the meantime, any ideas welcome !!

[007Cruiser]

The miss going up a hill is definitely a sign of a bad cop(s).

[Tbear]

Bad cop(s). Take it to Ford or someone who can stress test it.

[Greg S]

One bad cop, replaced all eight plus plugs. Problem solved. Thanks for all the replies.