dmaxximus

Looking to get some positive suggestions / help with this problem. Here's the deal....

I am getting a knock sensor / misfire on my port engine only:

1>Usually only happens when engine is warm, under load, and between 2000-3500 RPM
2>When engine is idling, it almost sounds like there is a spark jumping around somewhere but unable to locate.
3>I am running 10-20% 110 octane mixed with 93.
4>The motors are low 8:0-1 and 5-6psi boost.

Any ideas, help, or suggestions would be thankful.

GPM

What ignition box are you running, any chance it could be rotor phasing.

MILD THUNDER

iTrader: (3)

Are you sure its not actually knocking? Warm engine, low engine speed, heavy apache, possibly too much timing there? I dont see the need for race gas if its 8:1 with only 5-6lbs of boost. We been running that on 93 octane forever..with even more boost.

mike tkach

iTrader: (3)

i would replace plugs,wires,cap&rotor.carbon tracking in the cap or spark jumping from one wire to another.

F-2 Speedy

iTrader: (6)

^^^^ agree cracked cap ? maybe a wire boot arcing to the head, fire it up in the dark, if its an arc easy to see.

MILD THUNDER

iTrader: (3)

These are EFI engines? Or Carb? What ignition setup?

dmaxximus

I actually think it's a backfire, makes a snap/pop noise when it does it but the knock sensor goes off.

Accel DFI
Accel Rotor / Cap
Phillips Racing Spiral Wires
MSD Ignition 6M-2
Crane Cams Fireball LX91

MILD THUNDER

iTrader: (3)

Cap rotor and wires a good start. Sounds like it may have a lean spot in the curve too if its popping back thru the engine..

GPM

Are you running the dual sync distributor

sutphen 30

I'd check the valve lash again.