Quick question about the knock counter and knock retard. I'm using Freescan and have noticed that i am pulling timing some during part throttle driving along with the knock counter increasing at the same time. Unsure if its false or not yet. Still experimenting. I have plenty of noise that can be inducing it. What i'm curious about is when i go WOT, where i have a lot of timing pulled out, it still pulls some timing, but the counter has not gone up at all like during part throttle. What do you guys make of this? I'm thinking it may be false. I'm only running 24 deg in the 1.00 map range unter boost. Premium gas, FMIC with 50/50 meth injection and not running it up to full boost. Only up to about 10psi. Any ideas? Thanks.

Ken R.

 

Knock count is an elusive concept, at least to me. I've reviewed hundreds of data logs, and there are many cases where knock count is incrementing, and there is no knock retard, and other cases where there is knock retard and no change in the knock count. I'm guessing that knock count is a number generated internally by the PCM, based on the readings of the sensors that have a tendancy to be tied to knock potential - IAT, CLT, and MAP being several that I can think of. Again, just a guess, but knock count does not seem to be related to the actual signal being picked up by the knock sensor. It isn't a response to noise, just a response to conditions which may promote knock/detonation.

That might explain why the PCM reacts by incrementing the knock count when it sees irrational MAP values (irrational, because the PCM logic was not based on an engine running boost).

Just a theory, but it does seem to explain why incrementing knock count may or may not cause knock retard, and why you see so much of it under boost.

 

I've also seen this too. Just hard trying to figure false from real at this point.

Ken R.

 

One reason for retard with no increase in count is "burst knock retard." This is programmed in the stock tune, if a sudden increase in airflow happens, the PCM will preemptively retard the timing to prevent knock.

Those settings are changable with tuning programs. I have effectively programmed burst knock retard out of my tunes and see no knock happening. It's probably more of a safety "just in case" thing from the factory, rather than very necessary.

Fred, I've never seen counts increase without retard. That is strange. Could it be those particular tunes had retard programmed out (which is possible to do)?

 

Most of the data logs I'm looking at are out of stock PCM's. I have hundreds of them.

 

Thats when i would see the majority of my timing pulled, during a sudden increase in air flow.

Ken R.

 

Yep, that's burst knock retard. It's easily disabled (or lessened) in the PCM tune.