This is the story.
Car is corvette 1991 6spd.

After I installed my hotcam, 16rrs, lpe heads,and headers with open exhaust I got this knocks at the same rpm range all the time.
When the car gets hot I get the knocks at 1400-2200rpm. It doesnt matter if im under load or not. Its mostly at 2000-2200rpm. When I get abow 2200 no knocks what so ever, not even at WOT, its like you turn off a switch abow 2200rpm.

Im still running the stock chip, the car is very rich, BLMs at 108.

This is what I have tested.

Frist I retared the timing in the mina spark advance at that rpm range 10 degrees, no diffrent.
I used octane booster, no diffrent.
I have checked all the plugs, no sign of detonation.
I hade the car on jacks with a friend reeve the engine, and I whas all over the engine lissen for knocks. No strange sound, the engine is super smooth.

The only thing that bugs me is that the knock counts comes and goes. Sometimes I can drive the car at the critical rpm range. Then all of the sudden it starts- But ONLY at 1400-2200rpm?

Does this sounds like vavletrain noise to you? And false knocks?
Is there someway I can make the knock censor a less sensitive?

Thanks for your time..

 

Try adding some fuel in the areas just before the knock.

Using a pipe coupler with a 45d offset can deaden the K/S, but be real careful. You can get tip-in detonation and not trigger the sensor. Gotta read the plugs to make sure all is correct.

 

this is with the stock chip, så my BLMs are 108 all the time. Its super rich.
THe plugs looks fine.
I heard about the pipe coupler with a 45d offset . Is that something you can buy or do you have make it yourself?

What is tip-in detonation?

 

You're pegged at the ecm's threshold. I can no longer remove any extra fuel it's reading from being in closed loop. Don't go WOT but if you burn your own proms just lower that limit down into the 80's, I've done it before when I went from 18psi (max on the stock holley regulator spring) to 28psi. Just be certain you do the math and recalc the injector constant. Mine is set at 100 right now but it might need to go down even further.
It's hard to read plugs now with all the adatives in gas. Try setting your "knock counts needed before retard" to a higher value to be certain you're getting actual detonation.
Tip in is when you tip into the throttle. I consider it going from either idle or decell to actual accel without entering PE. The time it takes for my foot to move down is the "tip in."
The 45 offset can be bought from Lowe's I believe. I had to use one because my SLP tri-y headers got in the way of a direct hookup.

 

I had the EXACT same problem. 2100 rpms knock city, load or no load. bupassed KNock sensor = perfect for now. it was false knock. i also have a cam similer to hot cam, 1.6rr, TF heads and super ram. I'm also running the stock chip with blms around 126

 

If you back the cruise timing way down, and add a lil fuel you might be able to get them to color-up.

Using Brand X, Y or Z fuel and I can pretty much get mine to read right all the time. I'm typically in the high 20s at cruise, and high 13s AFR wise. Seems to be an all around winning setup for me, thou MPG did suffer a couple MPG.

 

i got a update on my knock probleme..

What my engine whanted whas to reduce the timing 200rpm before the knock started. And I alos added som fuel in the are just before.
So before I hade 29 degrees of spark advance, and I now have 24 + som added fuel.
My knock counts whent from 200 to 30 to my "trip to work".
I THINK the 30 knocks I did get is a exhaust leak I have, I can just hear it from the collector.

thanks grumpy for the tips
regards

 

a "strange" thing is that abow 2000rpm I can run 34 of timing advance with no probleme @ crusie. But when I get below 2000rpm, i must drop the advance to 25. But mayby thats just what the car whants? I dunno..