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I'm noticing in my logs the spark advance is always 5-12* higher than what the high octane table says it should be. My hunch is the computer is assuming ethanol content in the fuel and adding timing, but I want to know for sure. Is there a PID that tracks inferred/virtual fuel composition? What else could I look to know why timing is being added? I'm seeing some KR when the timing advances too far and I want to adjust whatever modifier is adding the timing. (2011 Silverado E38)
There are several spark correction tables that can add or remove timing. Anything from IAT temps to coolant temps and even the commanded EQ ratio in the calibration. If you have VVT that could also be doing something.
All of those things can be logged. You can log ethanol/alcohol content. Same with all those spark correction tables, that way it can show what it adding or removing timing.
Log everything with the word "advance" or "retard" in the list of available channels and you'll find out what's doing it pretty quickly. Could be PE/COT modifier, could be IAT, ECT, all kinds of stuff.. might be Ethanol content. There's an easy way to find out though.
Quote:
Originally Posted by 5FDP
Thanks for the advice. I know there are lots of things can impact timing. Looking at the common ones and their multipliers though, I can't make them add up to 12* like I'm seeing at times. Looking for any 'advance' or 'retard' PIDs to logis a great idea. I forget how versatile VCM can be.Quote:
Originally Posted by schpenxel
What is the PID to log the virtual ethanol content? The only ones I can find show 4.3% no matter what fuel I put in it. Even with a full tank of e85, it doesn't change.
There isn't a special channel to log for alcohol content. I usually log both channels for ethanol/alcohol content.
The virtual sensors are known to not work right even if the setting is set to enabled in the tune.