Black01M6SS

iTrader: (3)

I've been messing around with my truck and the timing is all over the place. At idle it hovers around 16-18* but a blip of the throttle will make it go off the charts in both directions watching the dashboard data logging. Seen it jump as high as 64*. There are so many tables that modify it but I still don't understand how it can jump up that high. The only thing I've really messed with is the high and low octane tables. Ive been filling it up with 92 which is the best I can find around here and logging to see if I get retard and usually I don't or very little but I question if its even normal for it to jump around like it does and which tables to modify and which to leave alone. Base spark, high octane, low octane, and the others that modify depending on engine/iat.

I read a post talking about a bad MAF causing a similar situation and it has me questioning it. The MAF frequency changes look normal to me. I'm not sure how high or low it should go but it responds and the truck runs great. I just don't remember ever seeing the timing jump around like that when doing a speed density tune on my car.

RamAirRocket

iTrader: (1)

Idle spark and off idle spark are different tables on some engines. You don't want to be running main spark tables at idle at all. It will cause an unstable idle that is difficult for the pcm to control.

I feel high like 64 would be too high, reality is around 45-50 is about as high as you would ever want to go or need to go. That time is only in an unloaded condition like decel. Look at the main timing tables (high octane) and then add in coolant temp adder and IAT adder and possibly EGR adder, see if you get close to your 64 value at that condition.

Not knowing what tune or tuner program you are working on, most have a high timing limiter, so even if the math calculates timing to go to 70 degrees, the limiter will limit to whatever it is set at, say 55 degrees.

Black01M6SS

iTrader: (3)

Thanks, that helps a little. I've only seen crazy values like that when giving it a rev in park. I have the p/n limiter at 3500. I've removed all the EGR stuff and disabled the system and MIL for it. I didn't even realize it had a table that adjust timing for it. I guess I should 0 it out now. Looking over the tables and how they modify eachother I just couldn't figure out how it could ever go into the 50-60* range but it will if you rev it with no load.

RamAirRocket

iTrader: (1)

What OSID are you using? What tuner program? I can see what I see for a limit on timing.