Trans Am

I used to have MAC's with the cat Y pipe. I recently just got QTP headers and a 3" Ypipe with carsound cats in it. After that the car would sputter really bad in part throttle and especially under load or at WOT. A friend of mine told me to change the plugs and fuel filter. I did both today with Autolite non platinum plugs and a fram fuel filter. Both helped the problems a little bit. By tuning from the MAF Translator i had even better results. When i had the macs on my car the settings on the MAFT were 5% lean base and 0 WOT. Right now im still on 5% lean Base and 6% lean WOT. The car runs much better than when i got it back from the header install but it still has problems above 4k RPM from part throttle and WOT. Mainly backfiring during WOT. Any Ideas?

Venkman

iTrader: (4)

sounds like what was going on with my friends lightning when he put the spark plug wires on wrong <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Trans Am

The wires were on correct when i got the car back and i put them back on correctly, the wires on these car are stupid proof...

black00WS6

I installed MAC's on my car and had the same problems. I didnt take my plugs out so while putting the headers in, it must have damaged a few plugs. I swapped out the plugs/wires and had no problems afterwards. Mine started out only sputtering and backfires at the same range of RPM you are saying, and after a few days of driving it, it got worse.

Slowhawk

iTrader: (12)

Try setting the MAFt to 5% rich base and give it a spin.
I've done a few Header installs and found that the MAFT has to go 5% rich after to help the L-terms.
Couldn't hurt <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
Also make sure there are no header leaks,expecially around the 02 area.

HOSS99

I had the same problem shortly after Header Install. It ended up being just a loose Plug Wire. I know you just installed new ones. Check to make sure there are no loose connections on the wires at the plugs or coil packs. There is always a chance one of your new plugs are bad, but not likely.

1BAD-SS

My roomates camaro did the same thing so we took it back to where he had the engine built and they told us that it was a plug problem and that if you keep driving it you will mess up a valve. Get it checked out by someone that knows what they are doing before it becomes an expensive repair. Better safe than sorry. Good Luck. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

REVZ

I also had the same problem after getting my lt headers installed. The shop didn't seat one of the plug wires properly.