Big_Steve

Hey guys, im new to this forum but not new to mustangs. When i go WOT at around 5,000 RPM, i get a bunch of back firing and it has a hard time going over 5,000 RPM. The car dose have some modifications, including an e-303 cam, GT40X heads, Aftermarket Throttle body, and C&L intake tube. Oh and it also has mid length headers with no cats. I was thinking it possibly could be because the cats arnt on it but when i got underneath it looked like the o2 sensor would go before the cats so maybe that wouldn't affect it. If anyone could help me out i would greatly appreciate it! Thanks guys!

FivePointOhh

whats are the spring specs on those heads? could be mismatched parts. is the backfiring out the exhaust or through the intake, you should be able to tell pretty easy.

Big_Steve

it is backfiring out of the exhaust.

Big_Steve

BTW i got the car with everything on it already. Right now im just trying to get the bugs out of it.

mjr46

has the car ever run right and or is this a recent prob that just developed??

Big_Steve

It has been this way since i got it, just its the next thing on the list to fix

WhiteFoxGT

Fuel issues? Check the plugs. The TFI could also be acting up

Big_Steve

I will check it out, do you think it could possibly need a tune because of all the upgrades?

mjr46

tune up maybe^^^^..it should run okay on it's own, I'd look at making sure the maf is clean and all tune up parts are in good shape and all plug wires in proper order and pushed on cap tight

Jerome99

valve float?