G56 RPM going up at shift

[up@12]

Hello Everyone.

I was wondering what is causing my rpm to continue to rise when I grab the next gear. It will only do this if my foot is to the floor. I put my foot to the boards and go to grab the next gear at 2500 ish or 3000rpm the rpm will rise another 500-700 rpm. Do I need to just shift faster or am I commanding to much of something. The g56 is a bit of a different animal to the auto's I've had in the past

Thank you

[KhakiCummins]

Are you off the throttle before you push in the clutch? There is a lot of energy in the rotating assembly at those RPMs. If you are not fully off the throttle before the clutch is disengaged, you are going from a highly loaded rotating assembly to one that has very little load. This will allow the engine to increase RPM before the ECM realizes the change in throttle position and clutch pedal positions and pulls fuel.

[up@12]

Thank you for the quick reply. From what I can recall I am off throttle. I have to head out tonight and will have a go at it again and just confirm that

[arinkuddy]

You should log it if you can.

I think my truck does this some times. From what I remember it looked like there was a delay from when I lifted on the throttle to when it stopped commanding fuel.

Sent from my SM-G935V using Tapatalk

[tylerltr450]

Like Arin said log it and get back to us.

However if you are to the woods with the skinny slamming gears I would bet the truck is still commanding fuel when you left off the pedal.

[arinkuddy]

I don't know if anyone found anything out on this but I figured I would post what I found. I've been living with it for a long time but its really annoying because I have to wait to be able to shift when RPMs finally fall. I tried changing to another os but that didn't help. You can see in my screenshot that it commands fuel for a long time after lifting. It could be excess rail pressure related. IDK what the solution would be, maybe lowering timing in the high RPM low fuel corner. That causes its own set of issues especially if you are running no pilot.
22969

[tylerltr450]

What is your CMD Demand vs acutal?

That is some interesting stuff you going on thats a very high RPM spike. Arin if you want me to run your tune I can after I put a new trans in later next week.

[arinkuddy]

Tyler are you referring to fuel pressure?

I have the main timing pulled back to -5deg in the region that causes the surge. That seems to help but I want to try pulling it further and maybe playing with pilot to keep the engine from missing when operating there normally.

Feel free to try my tune I have a lot of stuff going on in there so be aware if you have over 15% injectors, aftermarket CP3, don't want to turn 3800RPM, or run over stock rail pressure.

Also I think I have the rail pressure sag fixed that you saw in the screenshot.

22981

[arinkuddy]

23050

Pretty sure I found it. This pic was from HP Tuners there is a deceleration limit. I have messed with this and it seems to have fixed the issue.