can you have too low of spark?

[ozorowsky]

Let's say your running 23 degrees of spark, and get 2 deg. KR. You reduce down to 21 deg. of spark right?

How about if your running 0 deg. of spark, and get 4 deg. of KR. Do you start adding? What do you do? I'm at this situation right now. Thx.

[98_LS1]

0 degrees of advance or absolute timing? Check for things that might be causing false knock. Most short throw shifters (M6) cause false knock if you don't make sure they are tightened with LOCK TIGHT. Also, the torque-arm bushing/transmission mount, if loose, could cause it. If you have an older car, try replacing the knock sensors with newer ones (01'+). Unless you are running 15:1 compression and 15:1 AFR, at 0 degrees, you shouldn't get any knock, at least that's what I would think.

[jimmyblue]

With zero advance and 4 degrees KR you have to be
looking for false knock or straight preignition (from
compression stroke and hot spots etc.). The only
cars I've had, with close to zero base idle advance,
were 10:1 iron head Buick motors. And even then
the vacuum would push it up from there.

Too little advance and the charge is still burning when
you open the exhaust valve. That's "burnt valve" time.
You want most of the energy to have gone into expansion
and not still be chemical.

[ozorowsky]

SO in laments terms, what do you suggest?

[jimmyblue]

I would be looking for engine clatter (rockers / pushrods
especially) first, if you see big KR with no engine load.
You may want to play with the knock sensor sensitivity
params. But you don't want to desensitize them to the
point of uselessness. I think some other folks have
posted sensitivity settings changes that worked for
them. If it's a '98 then it wants the newer style sensors
(if that has never been done). Looks like that does not
apply here.

Cylinder imbalance, injector problems could give you a
single lean cylinder that's knock prone even when the
average mixture is OK (per the O2 sensors). In this case
I would expect the knock to be accompanied by elevated
current misfire counts that would lead you to the bad boy.

KR that only happens under load may be exhaust or other
banging.

[ozorowsky]

I'll mess with it a bit. Jimmy, we've talked a bit in past, it's going to be probably another month before I REALLY have time to tackle this. When time comes can I send you a log and have you look over it? Let me know what you think? The more I learn the more everyone will learn cuz I'll keep updating my programming for dummies guide. Let me know. Thank you.