Speedo with a Stall Converter

[rrmccabe]

OK this has came up before but no one has ever answered it. It appears no one knows.

When running a stall under hard acceleration the speedometer stops working. And from what I have gathered does not start working again until you let off the throttle and drop below 80mph.

Now we know the speedo has nothing to do with the converter itself and I am not excactly sure where the sensor is.. I think someone said once but I forgot :crazy:

But the engine is revving in a similar manner as with a stock converter. The transmission and drive train is doing the exact same thing. The vehicle IS moving and should register speed.

So I am thinking that there must be some correlation between engine RPM and transmission RPM getting out of the "normal limits" in the ECM and it just cant calculate.

Does any of the tuners have the ability to fix this?

Any ideas what this is? I am going Yank and not looking forward to losing my speedo. Its ALMOST enough to keep me from putting it in.

[rrmccabe]

Yep, thats what I thought :confused:

[kenmosher]

I haven't looked at it in depth, but here's some random info ...

There's 2 speed sensors on the trans .. input and output shaft. There are several different torque and gearing calculations based on these sensors.

My guess is that there is too large of a difference between the front and rear sensors that the torque calcs are wonked (or at least out of range) for the stock cals. Probably affects a lot of the outputs from the TCM ...

There are several different verficiation flags that check for valid data. Makes me wonder if something gets set to "Not valid" during the period where you romp on a stall converter?

[rrmccabe]

I haven't looked at it in depth, but here's some random info ...

There's 2 speed sensors on the trans .. input and output shaft. There are several different torque and gearing calculations based on these sensors.

My guess is that there is too large of a difference between the front and rear sensors that the torque calcs are wonked (or at least out of range) for the stock cals. Probably affects a lot of the outputs from the TCM ...

There are several different verficiation flags that check for valid data. Makes me wonder if something gets set to "Not valid" during the period where you romp on a stall converter?

I am with you on the "not valid" part as I really think it has something to do with an out of range.

I would think that the sensors in the transmission are speed sensors and assume they would not be much different operating wise that a stock torque converter since both are after the TC. Assuming there is no difference in slip in the transmission they should not know there is a stall??

It almost seems that it has to do with something between RPM and trans speed.

I have no clue, but I am almost thinking about shelving the new Yank TC until a fix comes out. Regretting placing the order at this point.

[Nukedog]

Gotta love the new 4L70's...:mad:

[Silver06SS]

I've heard the 07's don't do it because there is actually a vss instead of the calculation thing.

[sslowered]

So has anyone come up with an answer on how to keep the speedo working with a stall? Tuners?

[TonyGXP]

So has anyone come up with an answer on how to keep the speedo working with a stall? Tuners?

should be fixed soon... at least for Wester's tuned guys...

[ltz03]

i spoke with lyndon the other day for other things and had asked him about the speedo and TC and he said it wont be a problem in his programming and i am sure that the other tuners will be able to do the same. by the time i do a stall(early 07) i will be all set

[rrmccabe]

i spoke with lyndon the other day for other things and had asked him about the speedo and TC and he said it wont be a problem in his programming and i am sure that the other tuners will be able to do the same. by the time i do a stall(early 07) i will be all set

Thats cool. Be interesting to see how that works.

I will have his tune her for testing next week and the Yank goes in shortly after. See how it works :)

[PEDRO]

i dont care that it doesnt register on the speedo,hell i know im going fast and the slip will give my MPH. If on the street,i'll know my speed by the cop givin me the ticket with how fast i was goin:) .lol

[rrmccabe]

i dont care that it doesnt register on the speedo,hell i know im going fast and the slip will give my MPH. If on the street,i'll know my speed by the cop givin me the ticket with how fast i was goin:) .lol

Hahaha, Yea I forgot the cops put the speed on the ticket !

Well I would still like it fixed if they can. If Westers does it then that can be a challenge to ADM and Vector !

[rrmccabe]

Hey Matt,

How about an official response from you or Lyndon.

Is the tune you are sending me gonna work with my Yank (speedo issue)?

I really did not think this was that simple of an issue.



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