There was an oddball item with the 99'* that I mentioned to you at one time. If you tried to put TM to 640ft lbs the car would start, stall and make you pull your hair out. If you set it to 639.9 it would work great. There might be something similar in your tune, which is part of the reason I suggested and sent the harness to you. Since I've had a buyer and you didn't respond. Not being a jerk about it ...but try it or send it back, it'* been a year.

How are your O2'* reading during the 1900 rpm area, any odd fluctuations that might show an adder table is messing with the tune? With some recent stuff, I was reminded about how many tables we don't have visibility of, that may be effecting a tune.

Have you tried reflashing a totally stock file and seeing if the KR still exists?

I flashed back to the basic intense tune, no change.

Forgot about the PCM, it'* on the shelf. I'll have to get it shipped back ASAP.

Why not try that pcm/harness first?

Haven't had time, nor will I any time soon.

I did a bit more experimenting on my way home from work. I get the same KR at 43 mph, now this is in 3rd gear and again, same 1900 rpm. Go up or down 1 MPH and the KR is again gone. I tried shifting to 2nd, but ran out of time before I got a good run at 1900 rpm. Keep in mind, I only get this KR at 43 and 60 when using cruise, on a level road, no boost, just driving along.

I ran my torque app on the way to work today, set cruise to 43 and got KR. Checked RPM, dash looks like 1900, torque said 1800 to 1825. Again, one up or down, and no KR. Level road. No KR going up or down hills.

cant think of what else it might be beside some kind of resonant vibration. you've replaced everything else. dont you have some mashmellow mounts laying around you could try for testing?

Ran another experiment on the way home. I did find torque is far more sensitive seeing KR then my aeroforce. I can get KR at 60, at 43, and at 25. Each of those is a different gear and about 1800 rpm. I also saw small blips of about .1 degrees when the engine would pass 1800 rpm. It has to be a harmonic, I can get it using my foot, or cruise. It seems the longer the engine holds that rpm, the higher the KR will rise.

What does your balancer look like is it old have you been swapping it from motor to motor.And how old is your coupler..Just trying to think of a harmonic type rotational part

All have been changed. NOTHING is the same from the first engine other then the supercharger, and that I took the belt off of and still had the KR. Now that I'm looking closer I see that it'* VERY specific as to where it is. As I take off from a stop, each time the engine gets to about 1800 there is a tiny blip, then it'* gone. If I accelerate faster, then nothing. Something is vibrating at that RPM, and no other. All sensors are different, anything, and everything that rotates has been replaced. At this point I think I'm just going to kill all KR in that very tight window.

Dan, I see in this link that you run Autolite 103 spark plugs with .045 gap. I tried to find103'* at Advance and they ended up not having them so they sold me Autolite Copper 606. They said to gap them at .060. I have a lot more faith in your knowledge of Bonnevilles so i gapped them at .045. Do you recommend .045 in the L67 SC motor?