06 with bucking cruise control during downhill coast

[foolkiller]

Hmmmm, then I guess my bucking cruise, that was cured with new injectors, shouldn't be cured either.



It boils down to the fact that the fuel system can't compensate for the leaking injectors.

musta missed a post..... if it works that's great.

 

[BILLVO]

I just got off the phone with him an hour ago and he says it is running great again with no more bucking. He Said they told him to use the 7 micron fuel filters from now on also.

 

[foolkiller]

nice... . i'll remember this one.

 

[jbpetersen]

They say, misery loves company - Mine does it too. Stock 06 automatic with a Banks Brake.

 

[HBarlow]

All Cummins powered Rams do it when factory new or with hundreds of thousands of miles on the odometer. It is normal and cannot be cured. It occurs because the cruise control is not quite capable of applying precise throttle to maintain speed when descending an easy grade. The grade causes the the truck to try to accelerate very slightly around the cruise set speed and the cruise control is trying to fuel just enough to maintain speed without slowing. All three of my Rams have done it.

 

[BIGNASTY]

It is normal. It occurs when the down grade is just sufficient to cause the cruise control to fuel very slightly then back off repetively as it tries to maintain speed control. My '01 and '06 did it and several years ago similar posts from other members questioned the same situation.

Dont know about NORMAL but had the same issue and only on down hill in cruise (then I thought why in cruise on down hill??) flat land not a problem.

 

[Tinman]

I had this issue with my 06 as well. Search my user name and there is a lengthy thread about it. In my case I had low flow in injector 6. The injector body was replaced when I had them tested and upgraded (50hp nozzles) at Dynomite Diesel. Problem solved. My observation was that is was fluctuating rail pressure (I have a gauge) that caused the surging. That being said I think bad injectors can cause this or make obvious a software issue. After seeing the erratic nature of the timing and pressure tables with EFILive, I feel this issue is partly a programing problem. If your cruise puts you in just the right spot on the curve it it can "bounce" the pressure a little and make for erratic fueling and the bucking. My problem was solved with a injector change, but once I smoothed out the pressure and timing curves with EFI, the truck ran much smoother and the rail pressure gauge stopped doing it's dance. Rail pressure is much more steady now. I did have a very subtle buck once after the injector was fixed with one of my EFI programs but after changing the pressure slightly it went away. This is one reason I think programing is partly to blame and that this issue seems to be much more common than bad injectors. My conclusion is that this might be a sign of a bad injector but it might also be normal on some trucks due to programming and perhaps mileage of the truck. If it is bad enough to not want to use cruise, I'd get my injectors checked.

 

[Tinman]

I thought I'd post and update about this issue. I can say with authority now that programming is the issue. I ran a different duration table last week and I got a good bit of bucking. Changed that table and problem went away. This is the first time I had any real issue since the new injector body. But changing the software created the issue then made it go away. I can't say exactly what is the culprit and it is probably a multi-factoral problem evolving many variables. And if there is a malfunctioning part as noted above, it can bring it on when it might not otherwise be a problem.