Truck retarding timing???

[dropem]

ok so i got my truck back up and running and it was running fine. But now once i go full throttle its really really sluggish and my aeroforce gauge says its only getting about 3-6 degrees of timing at full throttle.

Is that right?

And if not what would be making it do that

Oh and it idles fine if that matters

[GasGuzzler]

Not right. MY slow GMC with no FI got a new tune yesterday and I tested the KR to 100 WOT and got -1 and the 1-2 for less than half a second. Did you up the boost without a new tune?

[dropem]

no i havent messed with the boost at all but it is retarding even if i punch it from a dead stop even before boost becomes an issue

[mean05]

yeah it's caused by TM or the motor itself seeing knock...you can pull up to 15° of timing...i have seen them go into negative timing before

[dropem]

well how could u tell if the motor is seeing knock?

[GasGuzzler]

Hook up the scanner and tap on the side of the block with something non-metallic. Watch the KS frequency. Compare the test frequnecy to the frequency reading under load when the KR is happening. If they're close, you may have something coming loose.

How much KR is it showing? If enough to make the math work you probably have knock. If the KR is only -1 or -3 then the base timing somehow is goofed up.

I have heard of T/C stator problems causing this too. Need to make sure the converter is OK.

[mean05]

well how could u tell if the motor is seeing knock?

hook up Ryans laptop to is and scan it...watch the scan and see what it does...you can always email me the scan also and i can take a look at it...being turbo'd your main spark table is prob in the 15 degree area and also another factor is IAT's, the higher the IAT's the more timing it will pull....i say go log it and see what it's doing, that will give you the best idea of whats going on

[brobradh77]

trey I agree with virgil...get it logged.

[Sleaper]

I'm pretty sure that you won't see max timing until right before you shift or upper rpm's. In other words, if it's set for 15 degrees and you floor it, it will advance timing gradually throughout the rpm curve and not just give you 15 degrees immediately. Normally it stair steps to get you to max timing so that knock is minimized. Hopefully that makes sense.

Like everyone else said, there are other factors that will pull back timing as well.

At what rpm are you getting 3-6 degrees?

[dropem]

I'm pretty sure that you won't see max timing until right before you shift or upper rpm's. In other words, if it's set for 15 degrees and you floor it, it will advance timing gradually throughout the rpm curve and not just give you 15 degrees immediately. Normally it stair steps to get you to max timing so that knock is minimized. Hopefully that makes sense.

Like everyone else said, there are other factors that will pull back timing as well.

At what rpm are you getting 3-6 degrees?

yeah im def. going to log it but its getting it all through the power band all the way to 6000