Ken88GTA

I don't understand why I'm getting knock retard (as much as 9 degrees at idle)but it's not indicating any knock. There are times when it is showing knock AND retard so I know I have a problem but why would it show retard but no knock?

Also, I've tried to eliminate the knock by adjusting the timing, no can do. Cleared up a small header leak, no change. Knock sensor is 6 months old. Did a search on this, there seems to be different opinions as to what can cause knock counts other than detonation, what else might I look at?

Thanks,

Ken

Enkil

Knock retard doesn't go away as soon as the knock does.. So perhaps what you're seeing is just the knock retard left over from a knock that you didn't see with the scantool.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

Ken88GTA

I think I understand what you are saying, what I watched it do today was it read: knock=NO, knock retard=9*. It kept saying no knock with various degrees of retard. This went on for a while. Maybe the knock signal is too brief for the scan tool to reflect a change but as you said, the knock retard is of longer duration?

Thanks,

Ken

Enkil

Knock retard stays around for a while, and then slowly goes back to where it was.

If it sense a knock, retarded, and then immediately went right back where it started, it wouldn't protect the engine very well.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

Matt87GTA

The slowish baud rate of the interface with the cars ECM is likely the cause of not seeing the actual knock signal. You may also have a bad knock sensor. Does the scantool ALWAYS show knock retard with no knock (as in at all times when running)? If it does, something is likely not right. I have heard of some cars having an automatic timing retard setting in the EPROM that pulls timing out that might show up on your scantool in the knock retard data field. If you suspect the sensor itself, you can test it with the old 'hammer the block' method and watch the scantool for knock detection. If you already aren't doing so, run the highest octane gas you can find/afford as it will minimize the chances of knock occuring.

Some ideas.........

good luck

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, Home-made cold air system w/ K+N cone and AFPR, TB bypass, AirFoil, !AIR, !A/C, !EVAP, 2300 stall.

"Stop Lights timed for 35Mph are also timed for 140Mph"

Ken88GTA

Thanks for the replies!

Matt,

There are times when it does indicate it's seeing knock and times when it doesn't so you may be right about baud rate. I've always used 93 octane, there is a VP fuel near work, I think I'll check them out .
Do you know if additives like 104+ work?

Thanks again,

Ken

Matt87GTA

My view of additives is they are a bandaid and a 'mechanic in a can'. They are just not capable of doing the things they are advertised to be capable of doing. I don't personally run any additives in my car(s) but I have heard some good and bad things from others about them. Some people like them and others I know have used them and they did not change a thing as far as knock and performance goes. I would save the money from the additive and just use it to replace whatever part is actually causing all the knock. Is your EGR system working properly? If your EGR valve is not working it may cause the engine to knock excessively. Do you have any stored DTC's?

More ideas......

Good Luck......

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1987 GTA L98 MD8 GH3
355 '97 Vortec 4-bolt block, TRW(suck) forged pistons 10:1 CR, TFS 23*, LT4 Hot Cam, Ported plenum and intake, SLP Siam Runners, Edelbrock TES, gutted Cat, Flowmaster, Home-made cold air system w/ K+N cone, AFPR, TB bypass, AirFoil, !AIR, !A/C, !EVAP, 2300 stall.

"Stop Lights timed for 35Mph are also timed for 140Mph"