Timing questions

[Jaredpear]

I have a 1999 K2500 with a vortec 454 in it. I got a tuned ecm from black ear performance and I had a question about timing. When it’s cold it idles at 30 degrees adavanced and when it’s warm 27ish adavanced. My question is, is timing supposed to retard when I press the accelerator. During highway driving when I gas it but don’t downshift it’ll retard to as much as 18 degrees and from what I know isn’t my base timing supposed to be lower and then it advance with acceleration?

 

[Christian Steffen]

There isn't base timing in a computer controlled engine. There is just a high octane map, low octane map,idle map, and then modifiers for things like IAT, EQ ratio, etc.

Your timing drops under acceleration because the increased load increases the possibility of knock. If you were to hold that same throttle position and keep increasing speed you should see timing increase with rpm.

30 seems a touch high for idle, 18 is OK for low ish rpm, high airmass scenarios. It would probably handle more but I'm sure blackbear has to be somewhat conservative when doing mail order tunes.

Here is my high octane table for some reference.

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