When running the datalogger with a coolant temp of *35 my timing is at *20btdc. but it jumps around *5 degrees steadily. At 1500rpm, 5%TPS and *100 coolant temp my timing maxs at the preset *40btdc. Im pretty sure my chain has some slack in it. But isnt the timing pretty retard for that temp and load? I only run 93octane b/c thats just a pet peeve. Im not recording any knock except at start-up i had 2 knock counts. Are them 2 counts from the starter?

 

Your knock counts are possibly the "test knocks" that are induced by the ECM on startup/warmup. It will advance until it detects a detonation event, then adjust timing accordingly. I'm actually surprised there are so few.

As for the wandering advance, it may be due to the engine RPM operating near the threshold of an RPM step in the timing tables. As the RPM rises slightly above the threshold, the timing tables step to the next plateau. As the RPM drops just below the threshold, the timing advance is returned to the previous table entry.

Common timing table entries are at 400, 600, 800, 1,000, 1,200 RPM, and in 200 RPM increments up to 2,400 RPM. Since you may be operating near either the 1,400 or 1,600 RPM thresholds, the timing tables would be "flopping" as described. It is not uncommon to have over 7° steps in timing between 1,400 and 1,600 RPM, depending on the load factor. Another item to consider is that the tachometer is not 100% accurate, and you RPM may be closer to the thresholds than you might think. Coupled with timing adders for open loop, CTS, and other inputs, the variation you are observing is not beyond the scope of normal.

However, that is only my off-the-wall, simple-guy guess. Since I don't know much about it, I'll move this over to the PROM board where you might get some real help.

 

What Mr. Vader said. It's completely normal.

As for a "loose timing chain", I actually had one and through my data logging I was actually able to "see it" before I could hear it.

I started to notice knock counts CONSTANTLY at all rpms. The Knock Counter just kept accumulating quicker than my 1/10ths digit on my odometer.

Initially I was a bit perplexed and thought it may be my 300,000+ km timing chain, so I took my distributor cap off and then started turning the pulley on my harmonic balancer back and forth. I had a LOT of play before I would see the rotor on my distributor move.