MC2006GT

I just purchased a 2006 GT a week ago, manual tranny, 30k miles. 1st Mustang since my 1966 convertible decades ago. Prior owner said his garage had ID'd the misfiring as #2 and 7 COPs. He offered to split the repair to replace all 8 as part of the car purchase. I said I'd take the car as is and replace them myself. I purchased 8 MSD COPs and installed them last night but misfire still there. I don't have the issue in 1st or 2nd while accelerating through 5k RPM but I do in 3rd. I haven't been able to test yet in 4th or 5th, too much freeway traffic. The car is chipped with an older Diablo Sport that I haven't found a manual for yet. Anyone have ideas on where I start next to solve it? The chip?

danzcool

Plugs next, also just FYI, on these mustangs, MSD isn't the best option for COPs, the regular Ford ones are the best quality/dependability.
After that if it is still misfiring, you might want to take it to a tuner to see if they can ID the issue or clean up the tune.

MC2006GT

Thanks for the quick reply. Bought the COPs from American Muscle on their recommendation. Should have come here first. Showing my ignorance, I assumed if it was the plugs it would have happened in all gears. I know I saw a tread about plugs so I'll check that one out for recommendations. Again thanks.

danzcool

With plugs any issues pop up when more fuel is used, at higher speeds it takes more fuel to maintain the RPM level, more fuel can end up with spark blowout.
I say "can", as there is no guarantee that is the issue, just one of the less expensive options to explore.

MC2006GT

Understood it's not a guarantee fix but you're right it's a fairly cheap shot at a fix and they are 12 years old. I'll get the OEM plugs and hopefully get a chance to swap them out Sunday.

danzcool

Be sure to look at the info on spark plug removal, with a 2006 if they are the originals, they are a 2 piece design and are prone to breaking on attempted removal...
http://www.aa1car.com/library/ford_tsb_08-7-6.pdf

MC2006GT

Sorry this took so long. I did get new plugs. Had no problem with removing the old plugs, none broke. One of my new COPs did come apart when removing it. Had a long spring still attached to the plug. Did finally get it off a day later but the COP was broke, cap came off instead of disconnecting from the plug. Ordered a replacement for a different web site as no one locally had a single COP to match the 7 I had installed, only sets of 8. Got the last COP and new plug installed and the mis-firing is gone.

Thanks for the help.

FYI, won't be ordering anything from American Muscle web site. When I contacted them about getting a replacement COP they said to have the car towed to a professional and if that person agreed the CAP was defective there might be something they could do about it.

Dino Dino Bambino

MSD = My Spark Disappeared

danzcool

Glad you are back to 100%.

MC2006GT

Thanks. At some point I'll go back to the standard COPs. Other things to spend my money on right now.