delayed shifting?...

[inspector g]

hello. first time posting. I have an '01 3500 LB7/ Allison, mechanically all stock. When flooring it from a stop, the rig gets hung up in second gear and seems to just stop accelerating, although screaming, until finally getting into 3rd. what the heck? almost like a dead spot. i don't like it and have been dealing with it for quite some time now. any thoughts? if this is old news to some folks well, sorry.

[Kennedy]

hello. first time posting. I have an '01 3500 LB7/ Allison, mechanically all stock. When flooring it from a stop, the rig gets hung up in second gear and seems to just stop accelerating, although screaming, until finally getting into 3rd. what the heck? almost like a dead spot. i don't like it and have been dealing with it for quite some time now. any thoughts? if this is old news to some folks well, sorry.

How many miles since you changed the fuel filter?

I have a handy restriction gauge that will help dignose filter restriction and should stashed behind the seat in every Dmax. There are some odd 2001 tuning quirks, but this sounds like a classic example of a plugged filter.


http://www.kennedydiesel.com/images/Dmax-fuel-filter-rest1.gif

[inspector g]

Thank you. filter was changed in november '07. I will change the filter saturday and post results. that was not something i'd thought about. as for the restriction guage, where do i get one... thanks for your time.

[inspector g]

Thanks Kennedy! Amazing what happens when running a dirty filter. Makes perfect sense. I must admit that I generally drive conservatively and getting on it from a stop is not something i usually do. Probably the reason i was able to deal with the performance loss. I will grab one of those restriction guages and check frequently. Seems like the smart thing to do since I frequently pull my 8ton flatbed gooseneck.
That said, I've now got the performance bug. I see an intake and exhaust upgrade in the near future! Start with the foundation, right?
Take it easy and thanks for the input!

[More Power]

The Allison "adaptive learn" can also produce lazy shifting. Once the Allison has adpated to grocery runs, it'll shift somewhat lazy when the truck is then driven aggressively. This shifting delay usually becomes more exaggerated when adding power - at least till the Allison clues-in to how the truck is driven. :)

Jim

[inspector g]

Is the adaptive learn continuous or can it get to be like an old dog? I do suspect my tranny has bad manners.

[DmaxMaverick]

The adaptive learn process is continuous. Once you get an "old dog", however, it relearns slow, but it will. The feature has to modes. Fast and slow learn. Fast learn is initiated when the values are lost or reset (Tech II), and will get the behavior in the ball park very quickly. The slow learn will fine tune the shift qualities over a longer period of time. A "long period of time" can be a few hours to days, depending on your driving habits and type of driving you do at the time. A more abrupt driving style change will cause it to happen quicker than a subtle one. Changing from empty to loaded, or stock power to a programmer/box would be considered abrupt. More aggressive driving will expedite the process, as will more frequent starts/stops (vs. just lazy highway driving).

[inspector g]

I played "teacher" today on my commute to work. About a 60 mile drive consisting of 2 lane highway then single lane ,mixed 55-35mph, with lights and a nice stretch of hills; a good classroom so to speak. Not being sure of the way the Allison "learns" until now, i drove as if i was from new jersey. which i am. to my surprise, i noticed that the shifting got with the program quickly. Good Girl!
Later this week i'll be running hooked up and loaded. A nice abrupt change.

I've also got with the program... filters. Don't rely on time or mileage.

Did I say thank you? Never thought a machine could get lazy...