I recently did the TH400 swap (I had an M6). Initially, the speedo read double the actual road speed. Simply changing the tranny type to "auto" corrected this, the speedo is now dead on. But when I datalog with LT1_Edit, it is still showing double actual road speed. WTF is that about? I thought that the PCM drove the speedo?

Any comments would be welcome.

Rich Krause

 

You should do the correction with Tunercat, it always worked fine for me. Lt1_edit doesn't seem to allow change of as many road speed variables as Tunercat does...
If you want, you could send me your file and give me your gear/tire size info and I can modify it for you.

 

I will do that but I don't have it at home (it's at the shop) so will retrieve it tomorrow.

Thanks!

Rich Krause

 

It seems sometimes LT1 edit is funny when changing gears and stuff on that screen. Seems like if the speedo is working correctly then the PCM would be right also. I bet if you started with an A4 program it would work correctly. I've got an A4 file if you want that has the electronic tranny coded deleted if you are interested. You would have to copy all your tables over to it.

 

It was probably reading 2.35 X actual speed, because of the difference in the number of teeth on the A4 reluctor wheel vs. the M6 (40/17 = 2.35). I ignored the problem.... disconnected VSS. Keeps the odometer mileage down . But then I don't use the stock PCM for anything but tunring on the fuel pump and managing the IAC.

I think you need to do a complete reflash with an A4 program. Then defeat all the A4 tranny related DTC's.

 

I would appreciate the file!

Rich Krause

 

Do you drive yours on the street? Having a speedo is kind of a necessity, or am I being a wuss?

Rich Krause

 

Even like that, he'd still have to do it with Tunercat since lt1_edit has what... 1 code for a4? There's plenty of other ones to get rid of. I still think correcting the speedo in Tunercat would be easiest.

 

Who needs a speedo when you have a cage and a 5point harness?

 

Well i am having the same problem. 700R4 in an M6 car. installed 40 tooth reluctor on and it reads 2.35 * the speed. I have and M6 and a A4 computer from 94 f-bods. As well as LT1 edit for both of them along with the A4 file with the tranny stuff deleted(from brents site). Now I can open the file in LT1 edit and change all my values, but it wont let me save it cause the vin dont match. How do I do this? Thanks.

 

You have to upload it in the PCM first, then download it and then you'll be able to edit it.

 

Ok thanks. but will pcmprog let me upload it with the current vin stored in the file even though it dont match the ones that i am licensed too? Or will I have to do a Vinedit on the file first? Thanks for the fast reply!

 

Vinedit won't help, but yes, pcmprog will allow you to upload it even if the VIN doesn't match.

 

thank you very much!

 

The files I recieved from 94 NO TOP Z and Madwolf both worked fine! Wierd that the speedo and the PCM would read different spees though. Damned if I could figure that out.

Thanks.

Rich Krause