I have an 89 TII with a haltech, fmic, 3" exhaust, 550 prim, and 800 secondaries, street ported w/ 3mm seals.

We were out yesterday tuning with a wide band and under full or almost full load it would start to sputter, pop, or just die starting around 5500 rpm. Unless the wide band was lying, it was plenty rich.
I still have the stock plugs in place with are 7's lead and 9's trailing.
Would this be the problem? Could I have a faulty coil as well? It I was watching boost mostly but I saw the tach jump alot when it sputtered.
Any suggestions?
I'm going to try the plugs later today. I think the stock ignition should be able to handle it.

Matt

 

WHen I mean plent rich, I wasn't too rich. I forget what A/F ratio it was but I think 11 or 12 sounds about right.
I was running a max of 14 psi boost, but I also tried 10 and lower. I still pops and sputters a bit.
Popping, I mean backfiring, not detonation.