engine stubbles after acceleration.

stemo76 · #1 Tue, April 21st, 2009, 05:39 PM

Just received my custom tune and for the most part its really nice compared to what I had before.

do have one problem that I didn't before. When I pull forward or even step on the brake and then give a little throttle and let off the engine pulses. not so much on the tach but more with diesel chatter. the more throttle I gave it more noticeable the aftermath. I assume this happens when I am decelerating as well but the movement of the vehicle covers it up(I have an auto). Does this on 80+ HP setting and stock setting.

Any suggestions? I have the autoenginuty tool so I can get some readouts but its pretty new to me so I don't really know what to pull up and look at and then to know what it should say.

thanks.

Truck
late 99, stage IIb split shot, 4" banks exhaust, banks trans commander.
80+ hp chip from power hungry.

Rustler · #2 Thu, August 6th, 2009, 09:31 AM

I have a suspicion that if you disconnect the trans command your problem may stop. I own and have "looked" at several of Bills diesel tunes all of them had modified trans controls written in. I think they are conflicting with each other.

Very generally speaking in simplified terms.
Both the transcomode and Bills written in trans controls provide more clamping pressure to the clutch packs in certain circumstances to prevent slipping / put more powa to da ground. Moving a from a dead stop, decelerating and the OD shift creates the highest pump pressures. IMO.

My WAG is the pulsing occurs during the lag time difference between the electric command signal from the PCM to the trans to do something verses the mechanical time it takes to dump the extreme pressure caused by the dual trans controls.
The chattering you notice is the trans acting upon the engine during the time it takes to dump the pressure and release the clutches.

Or it could be the torque converter itself, the 99's were famous for being noisy, increased pressure makes it worse.

Or I could be wrong.

Dang, I just noticed how old this post is.

***Power Hungry*** · #3 Sat, August 8th, 2009, 12:55 PM

The thing about the Trans-command is that it is easily bypassed by installing the bypass plug in the harness. However, even though this is supposed to effectively bypass the Trans-command, we've found that it doesn't always work and complete removal of the unit is the only way to be 100% certain that it's not causing issues. Of course, this was learned from actual experiences with customer's vehicles.

I've never been a fan of the Trans-command as I've always felt it was trying to best guess what the transmission was trying to do. A chip or programmer ultimately has much more control over the transmission functions.