Stalling in reverse

2008 6.7 (two different trucks I have seen this on) stalls sometimes when you put it in reverse. If it does not stall completely, it will drop the rpms significantly low and barely idle when going to reverse. Loaded a tune on one time on one of the trucks and put in reverse and it would immediately die. Did a new full flash and now it will not stall completely or die but it will drop the rpms real low like it is going to die but will not. This is the same exact tune loaded both times. Have any of you seen this? Thanks

Have you changed the pulse table considerably in the lower mm3 range and low fuel pressure (idle area)?

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Originally Posted by cumminsDK

Have you changed the pulse table considerably in the lower mm3 range and low fuel pressure (idle area)?

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Actually in this particular tune I have not even touched the pulse table until you get to the bottom right of the table while the idling area is top left so it is untouched. Thanks for the reply though.

Let me go in and verify what I am telling you because I may not have changed that particular table but if I changed either of the other two scales (pressure and mm3) then that would in turn change the pulse by moving into another box or area

Find any issues?

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Originally Posted by cumminsDK

Find any issues?

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Well I thought as a test I would just try something. I went in to the idle areas of the duration table (main injection pulse) and raised the pulse width 10% and 15% just in the idle areas figuring I would put a little more fuel in to keep the rpms from dropping when put in reverse. This made no change at all, still dies when you put it in reverse. When put in DRIVE the rpms drop slightly and then come right back up but when it goes to reverse the rpms start dropping and it dies. I will continue to dig further unless anybody has any suggestions. Thanks

I thought maybe just bump up the idle but I do not see where you can control the idle like the 5.9? Something is causing the rpms to drop. Interesting note...I loaded an older previous tune that I did for this truck and then tested it. Put it in reverse and the rpms dropped fairly low BUT not low enough to stall or kill the engine. Loaded the other tune and it immediately died when put in reverse so something in the tune is causing this but I cant find it. Why not in Drive? Why not in Neutral? Why only reverse? Is this a load situation where more load is put on the engine in reverse and not in Drive? Now it does drop the rpms considerably in Drive but it does not stall. What is making the issue worse in reverse?

Another little thing I found interesting. If the truck is idling in park and you drop in reverse it will die but if you are idling in park and just before shifting to reverse, you slightly put your foot on the throttle and raise the rpms slightly above idle and then droip it in reverse with the rpms raised just a little and then once in reverse you let off the throttle it will idle fine and not stall.

Sounds like a duration issue to me, all auto 6.7s idle lower in reverse its annoying to me but that's the way it is. My presumption is when the ECM is lowering idle speed it is pulling mm3 and in doing so is referencing too low of a duration number to stay running

I'm not trying to point out the elephant in the room here, but these guys might be able to help you more if you posted up a log and the tune