Hey guys, can anyone tell me why my '87 GXL likes to backfire very loudly at and over 3800-4000rpm (monstrously loud ping when you're shifting gears). I was told possibly bad acv or egr valve. Also, having a problem with being able to switch my plug wires (from L1 to T1 and vice versa)and the cars runs the same (NO change whatsoever). Is timing just way the f*ck off, or what? Any help you guys could give me would be praised for centuries. Also, can you guys direct to some good mods/ how to's for mods for my 7 that i can do? Thanks.


'84 GSL limited (BBS wheels factory)
"opened up" air cleaner
custom 2.25" exhaust (no cat) w/ 40-series Flowmaster
drilled secondaries
no emissions,a/c
"lightened"~2100lbs

'87 GXL
3-cat exhaust removed, single 3in. catco cat

 

The backfiring could be caused by a bad Anti-afterburn Valve. Its on the ACV, I think. Next cause, your car is running rich. Timing wont really cause it to backfire, but you should set it anyways.