TCM vs. ECM same table, diff values....

[MMLMM]

OK i'm trying to get speedo to work perfect, and so when I adjust shift points I dont have issues.

In my stock ECM table VSS pulses per revloution show 40, and in the Stock TCM file they show 10

In my stock ECM file table Final drive ratio shows 3.73, and in the stock TCM it show 4.10

Any idea on this? Should I correct the TCM to match ECM, leave it???

 

[MMLMM]

Should I just make all my Speedo changes in the ECM and Forget about the TCM?

 

[TIM Z]

Bump for ya, Would like to see what the answer is.

 

[1slow01Z71]

All the tranny tuning threads Ive read everyone seems to just adjust the rpm shift point and not care about the mph. So that would leave me to believe that you should just get your ecm lined out and set your shifts points accordingly. Just basing that off what Ive read. Im just now starting to get back into reading about all this crap.

 

[DmaxHawk]

I checked on my tables and everything is the same except for the revs per mile on the tires. I just adjusted the tire size through the ecm and left he tcm alone, seems to work.

As for you, I'm not sure if changing those would screw something up....

 

[TrentNell]

i would try it and log and just be easy on it at first . but i dont have seperate tasbles for ecm/tcm

 

[SteveFord]

What I did was adjust the ecm first. Used a gps to verify the vss was right and then adjusted the tune from there. Then adjusted my shift points in the tcm were I wanted it. Doing it this way has gotten me within 200 rpms were I want it and shifts the same everytime.

 

[motohed]

i just gps'd the ecm and left the tcm. took more jackin around with it to change my shift points, but i just adjust them based off of how far off my stock to 35" percentage difference is.

i really love my tranny tune. ill post it up, but its set up for 35s and locks up pretty early. its perfect for my type of driving which is a lot of in town 55 and below with a bed full of tools

 

[motohed]

ok under allison tunes, the tcc lock up. its not the first one though. its further down the posting

 

[LBZrcks]

My ECM and TCM are both different also. Heard the reason why but forgot what the answer was.

 

[LBZ]

My ECM and TCM are both different also. Heard the reason why but forgot what the answer was.

X2. I have never touched the TCM only the ECM and whenever I do TCM changes the speedo always seem to stay the same.

 

[The Neens]

X2. I have never touched the TCM only the ECM and whenever I do TCM changes the speedo always seem to stay the same.

Yep, same here

 

[MMLMM]

Yep, same here

:rofl:

good catch Chris.


OK, I adjusted the ECM for speedo. Left the speedo part alone in the TCM. All my TCM tunes have quite a bit of changes. I was just trying to figure out if I will have issues with things clicking off in order if my TCM speedo stuff was off. So far so good never had an issue. I guess I'll play with it some more. Just looking for someone who has played with theres. (that sounds bad.)

 

[chevyburnout1]

I believe the ECM speedo file controls just the IPC speedometer and the TCM speedo file informes the TCM for shift points etc... :dontknow:

I've heard stories about the speedometer speed and tranny speeds sometimes differ slightly. Like sometimes in the TCM file if you want a shift at 20mph sometimes you have to set it a little above or below 20 for it to shift at actually 20mph. This has been my train of thought on it but I have no proven facts. Plus I haven't messed to much with the TCM anyhow.

 

[Lennart]

I did change my TCM to match the shift speeds closely. Changed H0103 till it matched

 

[LBZ]

Yep, same here

What are you trying to say?