I just wanted to get some info here on knock/timing. I know every car is different and reacts to various things (tuning, fuel, etc.) but based on what I've read and throughout my research, it seems that most people are seeing up to 3 counts of knock before any timing is being pulled. I've spoken to a couple tuners and they say it takes approx. 6 counts before the ecu pulls 1 degree. I'm asking this because my car seems to pull 1 degree for every 1 count of knock. I dont know if this is normal or acceptable, but because of this I have to be very conservative with my timing. I know my fuel is not the greatest (Jamaica has 90 octane **** water), but could it really be that? I doubt its the tune but roughly I'm about 2-3 degrees at peak torque, and about 9-10 degrees at redline. My AFR goes from about 12.0-11.8 during spoolup, and about 11.4 going just a tad richer till end.
Has anyone else seen 1 degree being pulled for every count?
I've attached a couple logs to show.

 

It is near enough a third of a degree per knock count. Since you are logging timing only to the nearest degree, this is why it appears inconsistent, but it is not. Read my knock routine thread if you want more info from the disassembly.

 

It's roughly 1 degree per 3 counts...I think the actual amount was 90/255* per 1 count of knock.

I think jcsbanks found this when going through the knock control. You may want to read through his thread again or maybe he can post here.

I forgot if anyone ever determined whether the ECU can actually pull a fraction of a degree of timing though. The logger will only log in 1 degree increments, based on the scaling.

Either way, the 'tuners' that told you it takes 6 counts of knock before timing is pulled...maybe you shouldn't be 'tuned' by them.

Edit: Looks like John clicked submit a few second before me.

 

Thanks for the reply. Yea jcs I think I need to take a closer look at that knock thread. Those were the only logs I could find at the time but I've logged before where 3 counts pull up to 3 degrees.
Well you guys are the pros so if you both say it looks normal then I'm good with that.

 

ok as a follow on question, will timing be pulled regardless of octane value? I sometimes see knock counts up towards 8 with no octane value reduction and I acn't be sure if timing is being pulled. this is of course separate from the part throttle knock I'm seeing that either isn't real, or just doesn't matter as the ECU doesn't seem to care.

 

Timing is pulled based on knock sum, other factors that confuse the relationship are interpolation and temperature trims to load and directly to timing. The engine speed at which octane updates turn on is slightly after that at which knock control starts, so you can have a big knock sum with timing correction that doesn't drop the octane.

 

I think that often the knock count and amount of timing pulled does not appear to match up because the logger is not fast enough to log every ignition event. Using John's DMA logging I think you might see a relationship closer to 1 degree per 3 counts.

 

Wreckleford could you point me to this DMA logger?

 

2 degrees

 

I've seen one count of knock effect the timing advance before

 

could it be that not all the timing tables are consistent?

 

It is built in to the live mapping software (if that is available for your rom)

Wut?

JCS banks has actually disassembled the code and seen the 1/3 timing per knock count. While I think its entirely possible that there is something else going on that we don't see, I have a feeling that the event you saw fell into the "not fast enough logging" category.

 

It's funny how John and I gave the answer and yet people are still giving bad information.

I don't think you guys realize how much time people like John have put into disassembling the routines to know the true answer. He didn't just pull it out of thin air.

This thread should have been finished at post #2 (I was posting at the same time that John did, and what do you know, said exactly the same thing).

 

So you don't think it was worthwhile for me to point him towards John's DMA Logging in order to hopefully allowhim to better see the relationship between knock and timing?

 

Not you, wreckleford. Your advice was good.

I'm talking about people questioning John or giving different information when he disassembled the whole routine and knows exactly what the ECU is doing...no guesswork trying to match up numbers in resolution limited logs.