T42 speed calculations

[v8vegaman]

Recently I have been working with a T42 and a 4L60E. When I run it on a dyno I get really high speed output numbers. 240Kmph. actual speed around 60mph. I went into the speedo calculator function of the programming and and the pulses per km are way big. toward the upper limits of efi live. When I change the tire size and gear an try to apply changes it wants to change 24856% ? so I apply it and it doesn't really do anything. My question is why is the number so high in the first place? The older LS1 speedo calculator has realistic numbers but not the T42. I have 1 T42 that has a 6 inch diamiter tire programmed into it from the factory? Is GM using a different format for calculations? I would expect to see numbers like 88000 to 133000 PPM but it not even close. Any ideas? I have a 40PPR speed sensor reluctor.

[MyM8V8]

Recently I have been working with a T42 and a 4L60E. When I run it on a dyno I get really high speed output numbers. 240Kmph. actual speed around 60mph. I went into the speedo calculator function of the programming and and the pulses per km are way big. toward the upper limits of efi live. When I change the tire size and gear an try to apply changes it wants to change 24856% ? so I apply it and it doesn't really do anything. My question is why is the number so high in the first place? The older LS1 speedo calculator has realistic numbers but not the T42. I have 1 T42 that has a 6 inch diamiter tire programmed into it from the factory? Is GM using a different format for calculations? I would expect to see numbers like 88000 to 133000 PPM but it not even close. Any ideas? I have a 40PPR speed sensor reluctor.

From what I remember, as I had a similar situation with my Ute, there is interaction with the cars BCM to give the output to the speedo with the T42.

I might be wrong, but I remember that when I brought the Ute back from new Zealand, I wanted to change the speedo from kph to mph.

I thought I could do this from the same speedo applet you have used, but whatever I tried failed due to the efilive cell limits imposed, so I'm still in kph. I was told that there was a mod' that could be done with the LS1 PCM to do effect this, but with the T42 it could not.(i.e change the speed units)

I am therefore very interested in where this thread leads to as I susepct it may be related.

[v8vegaman]

I will be able to check this out further in a week or so. I have the car running again and the E38 will have a auto trans programmed. I will post follow up info when it's done.