Missfire at idle
Thread Starter
Advanced
Joined: Aug 2005
Posts: 59
Likes: 0
From: Buckeye Arizona
Missfire at idle
My 98 started to missfire 2 days ago, it's a daily driver. It is not throwing any codes on the DIC. I had another 98 that had a similar missfire due to a bad plug wire found by a scan at the dealership. A friend told me Autozone would scan it for free, but the Autozone employee said the check engine light would have to be on and it is not. Not sure if I should spend $100 for the dealer to scan it or spend that $ on new plugs/wires. Is there anything else that would cause an occasional miss? I've been told the coils rarely go bad. Trying not to spend any more than I need to with Xmas just around the corner.
Thanks in advance for any help
Thanks in advance for any help
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
First item to suspect would be spark plug wires, next plugs (especially if they have a lot of miles on them). Wires can look "o.k." from the outside but damaged on the inside. And if they are the original wires, more than likely they will not survive the removal / re-installation process. So you should plan on buying new wires before you begin checking the park plugs. 
Thread Starter
Advanced
Joined: Aug 2005
Posts: 59
Likes: 0
From: Buckeye Arizona
Thanks Dan, any recommendations on plugs/wires? The car has 50,000 miles, I've had it for the last 10,000. I'm guessing the OE stuff is still there. LG street headers are in the plans, do I need a certain wire for that or will "cool socks" do the job? Is NGK's tr55 still a good way to go?
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
TR 55 on the plugs, Magnecore makes a good wire set, some folks like MSD's, some don't. I have MSD's on mine, no issues, but when I swap them I'll go with Magnecore.
If you have the stock plugs, no doubt the platinum pucks have fallen off, dramatically increasing the gap.
If it were me, I would go ahead and swap both plugs and wires.
If you have the stock plugs, no doubt the platinum pucks have fallen off, dramatically increasing the gap.
If it were me, I would go ahead and swap both plugs and wires.
Melting Slicks
Joined: Jul 2006
Posts: 2,094
Likes: 5
From: The 7th layer of hell - Western Washington
You say that it does this at idle, and not any other RPM correct?
Just wondering cause both my 97 Formula Firebird and my Z06 have a slight stumble at idle but seem to run fine otherwise. I was told this was common on GM small block EFI motors...
Just wondering cause both my 97 Formula Firebird and my Z06 have a slight stumble at idle but seem to run fine otherwise. I was told this was common on GM small block EFI motors...
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
Originally Posted by jbauch357
You say that it does this at idle, and not any other RPM correct?
Just wondering cause both my 97 Formula Firebird and my Z06 have a slight stumble at idle but seem to run fine otherwise. I was told this was common on GM small block EFI motors...
Just wondering cause both my 97 Formula Firebird and my Z06 have a slight stumble at idle but seem to run fine otherwise. I was told this was common on GM small block EFI motors...
