I'm having a backfire problem in 3rd and 4th gear while full boosting only when i hit 4000rpms each time i wot. My mods are in my signature and I'm boosting 28psi. I havnt had this problem ever. My car is detuned at the moment since the meth has been disconnected. Could this be a possible boost leak or spark plug problem. Any help or suggestions would be greatly appreciated.

 

change the plugs and see if it goes away...if your tune isn't up to par with the mods/fueling you are running you are going to be all out of whack

 

change the plugs and see if it goes away...if your tune isn't up to par with the mods/fueling you are running you are going to be all out of whack

 

I agree With That guy ^^^^^^

 

So i have changed the spark plugs. Car runs better but still has backfire with hesitation at wOT at around 4000rpms. What else could i check

 

check your FPR , make sure your set to 43PSI with your finger on the vacuume after disconnecting it from the fpr...

 

possibly a boost leak? Do you have a wideband? Either that or you car just needs to be redialed in.

 

i would close the spark gap alittle more. i would also recomend a ignition amp too.

 

How many miles on your 03?

Have you changed your plug wires? I had a similar situation, and forgot to change my plug wires at 60,000 miles. Once I changed them, problem went away.

Other than that, when you changed your plugs, did you regap them to a lower gap? This is important especially if you are running high boost.

 

lower gap and checking for arcing on the plug wires will likely show you your problem

 

No one thinks he could just be running rich?

 

doubt he is that rich to cause that.

 

I jst hit 80,000 miles. I have not swaped out my wires yet that was going to be my second guess. When I put my new plugs evo8 9's i gapped them at .028 which was recommened here for high boost high horsepower evo's. I turned down the boost from 27 to 24 psi... I'll try the new wires and check my fpr. Question could I have a cut in my fuel map cause of a mishap on a tune since my car was originally running meth and no longer is now without a new tune? This problem occurs on wot at 4000rpms each time

 

Thx again for all responses and suggestions

 

Mine was randomly doing the same thing until i re-adjusted my FPR, it was way too high for some reason out of the blue...