Off idle stumble and misfire 08 Coupe

[Loren jones]

08 Coupe, 23,000miles.
OK, over the winter I did full Belanger headers/3" cat back, catch can, smooth tubes, pulley, other miscellaneous other items. Anyway, car is up and running but has a off idle stumble, seems to be missing at idle and at higher RPM missing loudly, loud backfires as well on decel, although it did the pop,crackle before but is considerably louder with headers. Checked codes and had 4, P0098, P0100, P010A, P0113. All, I believe, had to do with having the air box out and battery disconnected. Cleared with scanner and they haven't come back after fully warming engine and trip around block. Pulled all plug wires and cleaned contacts, no change. Plugs and wires both have about 11,000 miles on them, Quality wires, plugs are stock replacements. Car came with Prefix/Arrow computer. It sounds like it is on the drivers side, not hearing it on the passenger side. I did have the scanner hooked up on drive, watched the fuel trims, but honestly not sure what I'm looking at. they mostly stayed under 10%. Also, I sprayed carb cleaner around vacuum areas, didn't notice a change, for what its worth. Any help would be appreciated.


Thanks,
Loren

 

[Steve-Indy]

Hi, Loren...it's been a while !

The number that I have for you will not work.

Give me a call if you like. I also sent an email.

Steve

P.S. The email bounced as well !!

 

[daveg]

Did you take the Wires off? if so, did you put them back on correctly?

 

[Viper Specialty]

If you installed it with the supplied junk composite gaskets and hardware... that could be the issue. Header leaks send trims all over the place.

 

[Loren jones]

@Viper Specialty I did use the hardware but used OEM gaskets, I found out about that before install. I will double check my install on the gaskets, maybe I missed something there.

@Steve-Indy I will give you a call later today. Thanks!

@daveg Fortunately, on Gen 4's pretty difficult to mess up the wires.

 

[Loren jones]

Also, don't think I metioned it but I have about 1oo miles on it after install.

 

[Cap'n Hook]

Battery voltage may be too low

 

[Steve M]

Did you leave the spark plugs in place during the header install?

You could have accidentally cracked a plug when you were fishing the headers in place, but that's just a guess. Given how cheap new plugs are and how relatively easily they can be accessed, it might be worth just replacing them to rule that out.

 

[Loren jones]

@Steve M , I did in fact leave them in and cracked one for sure and replaced it. Worth a look. Thanks

 

[Loren jones]

Well, I'm an idiot. Cylinder 7 had a cracked plug. Should have checked them when I cracked the other one. She rips now!! Thanks @Steve M , I owe you a beer, whiskey or cigar, something!

 

[BoondocSaint]

I dropped one of my sparkplugs while doing a recent tune up. I looked it over real good and ultimately decided it was better to be safe than sorry. Chucking it in the trash sounds like it was the right move.

 

[Loren jones]

Yep, for sure, lessen learned, slow down, double check everything.

 

[Steve M]

Well, I'm an idiot. Cylinder 7 had a cracked plug. Should have checked them when I cracked the other one. She rips now!! Thanks @Steve M , I owe you a beer, whiskey or cigar, something!

Just glad it was something fairly simple and that it is back up and running like it should be.

It takes a village to keep these cars going sometimes, but that's why we're here.

Cheers!