Got an issue that I can't figure out...
 

First the car/mods:

2002 Trans Am
STS T76 turbo w/ FMIC @ 7#
42# injectors and Racetronix fuel pump
Comp 918 springs
Jet-Hot long tubes
Wideband, Fuel Pressure, and boost gauge
TR6 plugs and Moroso wires

The problem(s) - not sure if they are related or what:

1) Cruising around at a set speed (no boost and not on cruise) I'll get an occasional hiccup where my A/F will skyrocket to 16-17 just for a brief second. This only happens after the car is hot and maybe once every couple of minutes.

2) Under boost A/F is fine, but a couple of weeks ago it started backfiring under boost. Turns out cylinder 6 was misfiring and replacing the plug made the problem go away. There was nothing visually wrong with the plug when replaced. *However* the plug wire had been laying against a header and was partially burned through (not to the core, but close). Today coming home the exact same thing happened, I was under boost and pop-pop-pop I started misfiring. I'm pretty sure I'm going to find it's cylinder 6 again.

Could the plug wire be causing my leaning while cruising and this (now) reoccuring problem with backfiring under boost? Are there other things I should be looking at (larger injectors? anything?)

Thanks much, this problem has me baffled - the car runs outstanding when it's running, but I'd like to get some ideas on what to do to get 'er fixed on a more permanent basis. :confused:

First and foremost, a turbo car and the heat generated by the turbo itself is it's worst enemy. Anything you can do to cut down on the heat will be a benefit. This can include ceramic coating the turbine housing, header wrap, wire wrap/covers, bigger fans, etc. More than likely, your wires and coil packs are suffering from heat and/or are getting burned by the extreme heat generated.

Check everything: fuel lines, fuel filters, all plus wires, all coil packs - make sure all are in good working order without breaks, flow or inadequate response.

The lean spike could be from the computer seeing issues with something electrical - wires or packs. Check them for continuity.

Thanks John! With the turbo in the back I'm fairly safe from a lot of underhood heat, but with the headers I'm sure it gets it's fair share. You hit on what I think is the problem, that #6 plug wire that's getting eaten up on that header. I'm going to buy a new set of wires... Is there a wrap for plug wires that will let them withstand the heat a little better? Thinking back (pre A/F gauge) I think I may have been getting these symptoms before the turbo install, with just the headers - I may have to look into some header wrap as well it seems :(

Yes, they make wire jackets for your plug wires. Make sure you have good fuel pressure in the lines with and without the car running. Rip the throttle a few times while watching a good fuel pressure gauge and see if it goes down. Always check the basics first....I've learned that the hard way.

Thanks for the help man :)

I have an autometer fuel pressure gauge, it reads 58-60psi all the time (both with the car running and off). I have no idea if that's good or not though :confused:

I use to get lean readings like that on my WBO2 when I had my AIR pump hooked up. It'd pump a small amount of air into the exhaust and the WBO2 would pick it up right away. Don't know it might be it if you still have your air pump hooked up.
Easy to turn off if you have a editing tool.
J:D

That's definitely worth a look as well! No editing tool here, but I'm bought into my local F-Bod shops LS1 Edit... unlimited useage - I will have them do a quit check next time I'm in, thanks!