Ok guys, today I got my datamaster software and cable, so I thought I would just play around and data log a little bit, such as the 20 minute drive I had to take tonight.

I'm looking back over the log and I see that immediately after starting the car it registers 293 knock counts. This number stays the same for 17 minutes, and it does not register any timing retard at all up until this point. About this time in the log I came to a not huge hill, but it widens to a double lane so I decided to pass this car in front of me. I had been cruising in 6th gear. I pressed the gas going up the hill and figured out it was going to take a downshift to pull this off in the time I had. I didn't downshift far, just 5th gear.

In any case the log shows the following.

TPS_____ RPM _____ MAP (KPa) __ Spark Advance ___ Spark Retard __ KC
38% ___ 1325 _____ 96.7 _______ 23 ____________ 0 _________ 293
44% ___ 1350 _____ 98.5 _______ 23 ____________ 0 _________ 293
47% ___ 1350 _____ 99.7 _______ 20 ____________ 0.6 _______ 364
47% ___ 1350 _____ 100 _______ 20 ____________ 0.5 _______ 364
47% ___ 1375 _____ 99.7 _______ 21 ____________ 0.4 _______ 364
47% ___ 1350 _____ 100 _______ 22 ____________ 0.3 _______ 364
47% ___ 1350 _____ 99.7 _______ 22 ____________ 0.2 _______ 364
47% ___ 1375 _____ 100 _______ 23 ____________ 0.2 _______ 364
47% ___ 1375 _____ 99.7 _______ 24 ____________ 0.1 _______ 364
47% ___ 1375 _____ 99.7 _______ 24 ____________ 0.1 _______ 364
47% ___ 1375 _____ 99.7 _______ 24 ____________ 0 ________ 364
47% ___ 1375 _____ 99.3 _______ 25 ____________ 0 ________ 364
47% ___ 1400 _____ 99.3 _______ 25 ____________ 0 ________ 364
47% ___ 1400 _____ 99.3 _______ 25 ____________ 0 ________ 364
47% ___ 1400 _____ 99.7 _______ 25 ____________ 0 ________ 364
47% ___ 1400 _____ 99.7 _______ 25 ____________ 0 ________ 364
47% ___ 1400 _____ 99.3 _______ 21 ____________ 0.5 ______ 436
47% ___ 1425 _____ 99.7 _______ 21 ____________ 0.4 ______ 436
47% ___ 1425 _____ 99.7 _______ 23 ____________ 0.4 ______ 436
47% ___ 1425 _____ 99.3 _______ 22 ____________ 0.3 ______ 436
47% ___ 1425 _____ 99.3 _______ 23 ____________ 0.2 ______ 436
Downshift
0% ______ 2150 _____ 75.7 _______ 34 ____________ 0 ______ 436
0% ______ 2275 _____ 30.3 _______ 34 ____________ 0 ______ 436
54.9% ___ 2100 _____ 29.9 _______ 41 ____________ 0 ______ 436
100% ___ 2175 _____ 102.2 _______ 27 ____________ 0.8 ____ 760
100% ___ 2200 _____ 102.6 _______ 28 ____________ 0.7 ____ 760
100% ___ 2225 _____ 102.2 _______ 28 ____________ 0.6 ____ 760
100% ___ 2250 _____ 102.2 _______ 30 ____________ 0.6 ____ 760
100% ___ 2275 _____ 102.2 _______ 30 ____________ 0.5 ____ 760
100% ___ 2300 _____ 102.2 _______ 31 ____________ 0.4 ____ 760
100% ___ 2325 _____ 102.2 _______ 31 ____________ 0.4 ____ 760
100% ___ 2325 _____ 102.2 _______ 32 ____________ 0.3 ____ 760
100% ___ 2350 _____ 102.2 _______ 28 ____________ 0.9 ____ 844
100% ___ 2375 _____ 102.2 _______ 29 ____________ 0.8 ____ 844
100% ___ 2400 _____ 102.2 _______ 30 ____________ 0.6 ____ 844
100% ___ 2450 _____ 102.2 _______ 31 ____________ 0.6 ____ 844
100% ___ 2450 _____ 102.2 _______ 31 ____________ 0.5 ____ 844
100% ___ 2475 _____ 102.2 _______ 32 ____________ 0.4 ____ 844
100% ___ 2525 _____ 102.2 _______ 33 ____________ 0.3 ____ 844
100% ___ 2550 _____ 102.2 _______ 29 ____________ 0.8 ____ 921
100% ___ 2550 _____ 102.2 _______ 28 ____________ 0.7 ____ 921
91% ___ 2575 _____ 101.9 _______ 28 ____________ 0.6 ____ 921
78% ___ 2625 _____ 101.1 _______ 30 ____________ 0.6 ____ 921
51% ___ 2625 _____ 97.4 _______ 30 ____________ 0.5 ____ 921
7.5% ___ 2625 _____ 72.3 _______ 40 ____________ 0 ____ 921


From this point onto my destination I encountered no more knock retard whatsover. I guess I was curious abou the knock counts. It obviously doesn't take too much to make a them fly up looking at the short time period that is actually represented here. That's no big deal to me, but I was curious about a few things. First, why did it register so many knock counts from when I first started it up? Could this be noise from the rockers before they get any oil to them?

Also on the spark retard, what is consider a lot? What type of scale are we looking at here? Mine never got above 1, is that measured in degrees? If so that's doesn't seem like a huge amount of retard to me. Also what do you think? Worthy of tuning or is it just picking up false knock because it hears my valves rattling under such a load of trying to pull that hill in a high gear? However if it was false knock it wouldn't have gone away when it retarded the timing right, so does this mean it was real knock?

Thanks guys, just trying to make sense of it all. I'm brand new to this software and you've got to start somehwere. All in all I think the data gathered is fairly good considering it's had 2 rounds of modifications since the chip was tuned, it was a guessed tune via the mail anyway, and I don't have heated O2 sensors either!


:cheers:

 

I've been running the same Datamaster program for a couple months now, & see the same results @ start-up. I'm told the knock sensors hear & record everything at start-up, including the starter solenoid & it engaging/driving the flywheel Etc. so that is why you see so many counts initally. I run only 92-93 octane so I installed the LT4 knock sensor & I now only see knock counts @ start-up W/ none during actual spirited driving. :D

 

Not sure how GM has their knock sensors set up but I can tell ya how they work on a big Mercury EFI outboard (hang with me.. the principle is probably cross platform).

On the Merc, the ECU gathers knock data from idle to 2500rpm (which corresponds to a high load, planing condition on the engine). This is the rpm band where real knock is highly likely but not detrimental due to the low rpm. The ECU uses the data in this band as a reference knock.

Later on in the rpm band (this is a boat so higher rpm always means more load) the ECU is looking for a knock signal and constantly compares it to the reference signal. It keeps advancing the timing until it receives a knock signal equal to or greater than the reference signal. At that point it rapidly retards timing to a safe level.

Looks like the GM unit may do the same thing. The ECM/PCM is always registering some type of knock value and keeping count. But it only takes action when the signal is greater than either a reference signal or some pre-programmed value.

Hope this makes sense. And, of course, I may be completely off base too :)

 

Looks perfect to me.

The system tries to advance, the maximum value, detects a knock, (you'll never hear it), and pulls back JUST ENOUGH. Then, starts all over.

If you EVER hear a knock, on any vehicle, you are deep, deep, deep into "spark knock". Love that computer control.

Now, did you type in all them numbers?

dlmeyers 90 coupe zf6 3 speed shocks