Strange detonation issues

[forcefed86]

Helping a friend tune his car. E85 8.5:1 6 bolt block 1g head. BC 280 cams straight up. SD, GT35R, tuned with AEM EMS.

Keeps logging knock when not in boost. Usually around 0-10inhg of vac. I've tried locking all timing cells to 18* with no change. Cruise timing is 32* max no knock at cruise. Verified 5* base timing. Pulls strong to 25psi. Zero knock while in boost. So we assume it's phantom knock. Pulling the plugs shows otherwise. They are very speckled. Installed a new set of plugs Bp8es turned boost down to 16-17lbs. Peak torque timing at 15* ramped to 18 by 7000. Drove the car 150 miles. Same issues no knock logged in boost. Light knock at higher load accel but not in boost. 4-15* of knock. Pulled plugs and they are still speckled? This thing is defiantly detonating.

Tried a new CAS this time around with new plugs. Boost turned down to 12psi (low as it will go). The turbo has spiked a bit over 35 psi and did log knock at these levels in early tuning. (fuel system maxed).

Any ideas? this one has me stumped.

 

[livedsm4g63]

What are your settings at for it to show knock? Tps wise along with speed.

 

[Arthris]

With e85 and those timing numbers It should not be knocking. I wonder if it is running to lean. Do you have the Wideband set for e-85? If not I would look into that. As lambda for e85 Is a lot richer than gasoline. Just food for thought.

 

[livedsm4g63]

You dont have to switch that. Your car may be reading knock but it may not be knocking at all. I bet those values are zero'd out and it is picking up everything.

 

[forcefed86]

Yes we have a WB02. Tried everything from 11.0-12.5 on the AFR's. No change. The Knock sensor is setup correctly. I can bypass the knock I'm seeing down low and it won't register. But the plugs are still telling me there is detonation. Have also tested the "e85". It's around e70 (winterblend). Still plenty of octane for boost/timing being run. Something has to be off in the initial setup. Something is causing these plugs to pepper. I just can't figure it out. Idle is great etc.


I did notice something slightly off. My timing light is adjustable and picks up RPM. Idle rpm reading is all out of wack on cyl1. At 900rpm it read 1850-2200 and jumped all over. This didn't seem to bother the initial timing setup. The timing mark was very visible and was easy to set. But if I place the inductive clamp on the #4 cylinder it reads RPM perfectly. A new set of wires/plugs did nothing to change this. All plugs appear to be firing clean. Gapped properly etc. Could the coil be cross firing internally? Even if this was the case I don't see how this would cause detonation on all the cyls. All the plugs are "peppered".