smarty and transmission

[brods]

Okay, I hear opinions on what Smarty setting will kill trannys faster. I still do not hear an explanation for Torque Management. As I understand it, the stock programming for these trucks includes a functionality we call "Torque Management". This limits the engine's torque output to what level, when does it do it, and why? Once this is understood, we can understand the difference between what the Smarty and Bullydog are doing. It sounds like the smarty's TM settings are referring to changing the stock TM parameters, and the bullydog's is something different entirely. Torque management is used by manufacturers to save drivetrains, and it is usually done by de-fueling (right?). My '00 Camaro did it during shifts. It sounds like our trucks do it off the line to keep from spitting drivetrain all over the road. If done with fueling, it is the same thing as low end fueling. If anyone could explain the torque management logic on our trucks I would appreciate it.

Very good questions. Hopefully we’ll get some answers, but for various reasons I doubt we will (I don’t meant that as a slam against anyone, it just appears to be another one of those complicated issues where factory information is scarce and the few in the aftermarket who really understand it feel the info is proprietary).

well, in my opinion, its not Tourque Management (or lack of) that kills transmissions, but low end fuelling. I think Marco gets these two confused sometimes.

TM or fueling, as HLewallen asked, what is the difference? Other than dumping boost with the wastegate, which still requires a reduction in fueling I would think, what else is TM besides fueling?



As far a factory TM, does the ecm or pcm compare engine rpm to transmission output shaft rpm and calculate slippage based upon what gear it is in and then de-fuel from the programmed fuel map? Or is the stock TM really just fueling maps designed to keep the torque below a safe level based on dyno tests DCX/Cummins did when developing the ecm program?

 

[RobertP]

Very good questions. Hopefully we’ll get some answers, but for various reasons I doubt we will (I don’t meant that as a slam against anyone, it just appears to be another one of those complicated issues where factory information is scarce and the few in the aftermarket who really understand it feel the info is proprietary).







TM or fueling, as HLewallen asked, what is the difference? Other than dumping boost with the wastegate, which still requires a reduction in fueling I would think, what else is TM besides fueling?



As far a factory TM, does the ecm or pcm compare engine rpm to transmission output shaft rpm and calculate slippage based upon what gear it is in and then de-fuel from the programmed fuel map? Or is the stock TM really just fueling maps designed to keep the torque below a safe level based on dyno tests DCX/Cummins did when developing the ecm program?

our trucks know when to lay off of power, they do read slip, and tq managment is designed to reduse the amount of tq the engine can make so it does not damage other components

 

[Reb.B]

Brod, ... ... ..... to try to answer the best I can, which is not the factory answer, just the answer i can derive from my tests, ... ..... TM is a lack of fuelling. So then you also asked why does TM kick in. I say when it sees too high RPM in any gear (autos) it pulls the fuelling back. The dodge don't calculate like the fords (I THINK?) So far, as i know, the dodges will measure RPM drop. If its too much drop or not enough it throws the p1740 code. This is why some trucks 03-07 will throw a 1740 code when the converter is too tight. As far as the fuelling goes i don't think its a whole other map, but a limit on the original.

 

[brods]

The 05 service manual says the following about the P1740 code: “Set Condition: The DTC will set if the expected RPM drop is not achieved while attempting to engage TCC or O/D. This indicates a malfunctioning torque convertor or overdrive clutch. ” It makes sense that a tight converter has less rpm drop when it locks up compared to stock and if it is less than the minimum drop expected by the ECM the P1740 code would set. Not clear how that would be connected with torque management. Does converter lockup and OD get disabled when the code is set?



The service manual lists the TCM (transmission control module) as part of the ECM for the diesel. If I understand this correctly, the TCM is like a subroutine in the ECM. One of the outputs listed for the TCM is a “Torque Reduction Request”. An indirect input is listed as “Torque Reduction Confirmation”.



This must be the Torque Management aspect being talked about. I assume the TCM determines slippage by measuring input shaft speed and comparing it to output shaft speed. It would seem comparing the shaft speeds to detect slippage would work the same for stock or built trannys. So why would anyone want to disable the TM feature when it does not kick in unless there is slippage?



Is the Torque Management subroutine enabled all the time or just under specific conditions?



Is there just one torque management subroutine or are there several triggered by different sets of conditions?



If the Smarty modifies the TM program does it also change the TCM programming to increase line pressure sooner or use some other control strategies to help the transmission handle the extra power?



I guess the most important question is why the TM program cannot protect the transmission regardless of which performance software modifications were done to the engine? Is the ECM limited in how much it can de-fuel?

 

[Reb.B]

well brods, its not input shaft speed (because there is no way of checking input shaft speed) but if they are checking a speed (which they could very well be doing) then it would be engine RPM vs. trans output speed. If this is correct, then a tighter converter will have will have less TM. You asked why would anybody want to get rid of TM, and my answer would be that the TM isn't (really) helping me save my transmission, its just not letting me rev like i want to rev going through the gears.

For your question about a box increasing line pressure(at the bottom), that would be a good thing on a box with low end fuelling. A box can't increase top end line pressure. Dave Goerend and I have been talking about this and I have personally asked Marco to look into this. What comes from it i don't know. Lots of testing and hours and i'm not sure if anybody is going to be that inthused. Keep in mind, that if u own an 06, when using tow haul, you will have higher low end line pressure. This is a good thing and should be used with heavy low end fuelling boxes.

 

[GaryCarter]

I did some reading on this a while back, here's what I recall. Torque management is basically a means of reducing engine torque (defueling) when shifting the trans.

-TCM wants to shift gears; sends request to ECM for reduced torque.

-ECM sends response back confirming TM request.

-TCM does the gear change.



As I recall earlier models the TCM was a seperate piece of hardware & software. Around 2004. 5 or 2005 the ECM was upgraded to handle the trans too, so now the TCM is really just a subsection of the ECM.



Gary

 

[Reb.B]

that sounds exactly right.

 

[brods]

Gary, do you recall where you found the info? So far this is the only thing I could find on TM relating to the diesel: “Contributing to the durability and long life is electronic torque management - limiting engine torque build up when initiating acceleration from a stop. ” This is definitely different from the request for a shift.



RebB, I guess I got faked out by the service manual. It lists input shaft speed as a direct input to the TCM. Looks like that is only for the 45RFE/545RFE though. Too bad, it could probably be used to save some trannies.

 

[Giachino]

Keep in mind, that if u own an 06, when using tow haul, you will have higher low end line pressure. This is a good thing and should be used with heavy low end fuelling boxes.

What did they change for 06?

 

[Reb.B]

06 has the tow haul option and O/D option, and when tow haul is on line pressure raises. 05 has a taul haul and no O/D off and my guess is that they also raise pres. in tow haul, but i have not tested yet. 04 has tow haul, but its more of a O/D off than a tow haul and it also has a manual detent lever so line will not go up other than linear. The 05- present has a motor for the detent, and can manipulate line pressure as it sees fit

 

[Signal73]

so are you saying the 06's will handle more hp a little better?

 

[DJKosa]

so are you saying the 06's will handle more hp a little better?

I would say thats a stretch 06's have a TV motor on the side of the trans thats how they get more line pressure off the bottom in tow haul mode. That is the only thing that makes the trans hold better than an 05. Personally I would rather have an 05 without the TV motor, for reliablity reasons.

 

[Signal73]

gotcha. will have to keep it mild when the smarty finds its way into my mailbox... .

 

[Big P]

05's have the TV motor, no cable.

 

[DJKosa]

05's have the TV motor, no cable.

I stand corrected... to many trucks going thru mind... .