I finally had some time to have the wife drive the car around while I looked
at some parameters with my HPP. It looks like under hard acceleration / WOT
runs I get 1* and sometimes 2* of knock retard. It's interesting to note that
when you shift the knock retard goes to 3* but then back to 2* when WOT is
again applied.

Any ideas on the knock retard? I have comp pro mags, "R" lifters, and LT4 ED
timing set so there is lots of stuff to make noise. The "Rs" are set to 1/8 turn.

I also did a search and did not find what I was looking for.

 

I'd throw some race fuel in there and see if you still get it. Drive the car till you have about 1/4 tank, add about 2 gallons of 104 unleaded and drive the crap out of it and see if you still have it. If you do, then it's bound to be false, if not then it's real and you have something going on. I'll lay odds that it's false knock and nothing to worry about. 1-2 degrees isn't that bad IMO, but 2 degrees can cost you like 10 ft-lbs of torque on the dyno.

KR at the shifts is normal from what I understand.

 

Great idea on the race fuel. I have a local oil company that has the Unocal
100 unleaded. Putting about 5 gallons in a tank should yield an octane of
about 94. What are some of my options if it is false knock?

 

It can be desensitized through PCM programming. I've also heard of people wrapping the knock sensor threads in teflon tape and reinstalling to help get rid of false knock.

Dan

 

There is a resistor mod you can do to de-sensitize it as well. You can use two resistors in the wire to the knock sensor to tone down it's sensitivity before it gets to the PCM. The values of the resistor are dependent on the percentage that you want to tone it down.

 

Thanks for the info. I have an electronic guru friend and he can probably
come up with the resistor combination I need. The teflon tape idea sounds
good but I don't want to deal with draining the coolant at this point.

If if remember from some of the many posts that are out there on the
resistor topic, you have a simple dividing network where you use two
resistors and a tie to ground. This is the one that I found a while back:

http://www.charm.net/~mchaney/knock.gif

 

That's exactly it, only you can customize the resistance values for the amount of desensitization you desire. There is a little program that someone wrote that you enter a percentage and it shows the drawing with the proper resistance values.

 

Truedual; I had a similiar problem. My cure was put on the LT4 plastic covers! Yes you heard me right. The LT4 plastic covers were designed not only to look cool but absorb the extra valve train noise of the RR. I noticed almost instatly a major difference in sound from the engine. I have seen a few people with cheap alumimum covers off e-bay knock retard like crazy because they work as am amplifier! Sounds like you got a box or rocks in your engine. Engine noise in a knock sensor motor is bad. Just my 2 pennies.

 

That's interesting and seems to make sense to the naked ear, but with the knock sensor being located at the bottom of the engine and in a water jacket, I wouldn't realize that something like composit valve covers would make that big a difference...

If a man wanted to test that theory, he could cover a set of extra covers with some sound deadening material, or rubberized undercoating and see if it helped.

Something else that I considered at one time, was to put some sound deadening material on the knock sensor itself to isolate it from outside noise altogether.

 

Lwill;
I was hitting about 1-3 degrees at WOT before the covers 0 after. The before and after was within 1 hour under same conditions. And the side benifit was reduced noise to the ear. I makes sence to me as an engineer. The steel covers reflect the noise the plastic absorb, much like sound deading material on your car. I actually thought about sound deading material on the covers first. But did the LT4's instead. With Dal and Jason selling new for used e-bay prices i couldnt pass it up. If you want to try some bed liner or something on some stock covers let me know and i will send you a set! You can be the test guy!

 

Cool! That's great news then... I'm going shopping for some composite LT4 covers...hehe

And no, I'm NOT trying to be sarcastic here, I've got a slight knock retard problem too. 1-2 degrees at times.

 

Are these the correct part numbers for the composite LT4 covers?

P/N 12552321 LH and P/N 12552322 RH

 

Those are correct for the covers. You will also need 8 studs # 10108674 and 8 screws # 10108675 and the oil cap #12555685 i bought the whole set for $210 new from Dal. I try to spread my GM parts purchases between him and Jason

 

How would those covers fit with a valve cover breather?

 

Dont the stock system is fine for PVC venting. The hose connector is on the edge of the cover so if you got creative with duct tape, a staple gun and some silly string you should be able to fab one up