N20GMC

What exactly is DFCO because my truck does the exact same thing.

MikeGyver

iTrader: (5)

Deceleration Fuel Cut Off. If you have stock values, in other words if you or your tuner haven't messed with it, then it is not the cause of your issue.

closet red neck

iTrader: (6)

Well zeroed them out, took the truck on a drive and the jerking went away. It still goes to lean but the fuel cut off then on again(hence the jerking) has went away. By zeroing out the values it cuts the fuel off and keeps it off so then the truck just decelerates. No jerking.......

James

closet red neck

iTrader: (6)

Personally Corey I've never seen a noticeable difference having it enabled other than the severe "braking" effect. I disabled mine and never looked back. When you go off throttle and back onto the throttle I never liked the jerk or lash that the DFCO caused. It's much easier on your drivetrain to leave it disabled.
__________________
-Joe
This is what I did.........gonna see how it works out and let ya'll know....

James

MikeGyver

iTrader: (5)

Technical bulletin:
It does not cut the fuel off, is disabled. The jerking came from it turning on (cutting the fuel), and turning off (turning the fuel back on), turning the engine on and off. With DFCO enabled, and you let off the throttle, the fuel cuts off when the engine speed falls to the DFCO entry rpm. Then rpm drops rapidly to the DFCO exit rpm, and the engine cuts back on instantly.
When DFCO is disabled and you let off the throttle, the engine tries to return to idle. It does not instantly go to idle because of the throttle cracker and follower tables. When they are correctly set up, they act like a carburetor with a closed throttle, in that the carb lets a little air and fuel through when you let off the gas, allowing the engine to gradually return to idle.
DFCO might be nice if you could enable it manually, like maybe a button on the gearshift, to use engine braking in the hills.

closet red neck

iTrader: (6)

Thats cool.........so when disabled, it turns the fuel on?? When enabled, the fuel gets cut off??? But never the less, the fuel gets turned on and off hence a jerking feeling. The fuel being turned on and off was the best way I could describe what I was feeling. After the modifications I did to the tune, it went away. I will say this, it acts like a "jake brake" now. I kinda like it because when I'm hitting the 130mph range the engine helps me slow down. I'm gonna play with it some more and see what I can screw up.

Thanks for your help...

James

Atomic

iTrader: (42)

I personally like it enabled, I dont have to use the brakes near as much.

MikeGyver

iTrader: (5)

It cuts the fuel off. When it is disabled, it does nothing. When enabled, it does what its name implies.

closet red neck

iTrader: (6)

Well with the hold, entry and exit tables zeroed out, I'm assuming that the DFCO goes into instant mode(if you will).....its still enabled in the fuel control/fuel cutoff tables. I left that alone. When letting off the throttle, its instant "jake brake" and when barely appplying the throttle, the "jake brake" in instantly gone. This is what I noticed this morning while driving on the interstate.

James

Atomic

iTrader: (42)

Yea, but I have mine set so it really only applies at highway speeds.