Driving down the freeway today I rolled into it in 5th (about 3500rpm) and was greeted by a harsh misfire. It jerked the whole car, and also produced a metallic ringing sound from the engine bay. I tried again and was greeted with a similar result.

EGT's were 1350F front and 1450F rear. Probably 4-8psi of boost (definitely under 10), AFR ~10.5:1 and dropping.

Any ideas on what's going on? Car is a TII with 60-1, haltech, etc. Could this be a rich misfire, possibly causing detonation? I think I'll pull 5 degrees of timing and try again tomorrow. Not going to be happy if I grenade the motor!

 

Whats your ignition setup? coils, plugs, wires, etc?
How much advance?

10.5 is pretty rich for 4-8psi but with a good ignition shouldnt be hard to ignite.

 

Lean it up to mid 11s. Thats just too rich.

 

stock TII ignition with 9's all around. 25 degrees of advance at 0psi tapering linearly to 12 degrees at 15psi.

I'll lean it out this evening. With luck it didn't damage anything.

 

Sounds like a misfire from your ignition not being able to fire it. It's not gonna hurt anything but fix it.

thewird