car have a loud backfire when i hit around 7500-7800 RPM in my turbo s2000 with WOT. I see some white smoke came out when i look in the rear view mirror. it sound like a gun shot. car wasn't doing this couple days ago when i got it tuned. check spark plug and regab to .026" and it's still doing it. Spark plugs going out?

it only does it in first gear, the other gears are fine.

 

fixed. bad spark plugs, change it out with a spare set and gab it to .025 and it's running good now.

 

Could be ap1 Coil packs. Mine was hitting a brick wall on the dyno at 7500 rpm's even with the plugs gapped way down.
Swapped to K series coil packs and the problem went right away.

 

From which year k series? Are they plug n play?

 

Interesting you say that as mine did the same at the exact same rpm. Never had it back to the dyno.

Coil packs fixed it ya say? So you re-dynoed and that was the cure?

Funny thing was I could never tell it was hitting a brick wall while driving, it felt strong. Only the dyno showed it was having difficulty.

 

We swapped them on the dyno and it Pulled right to redline with a bigger gap on the plugs.

 

Good to know. Muchos Gracias.