rel3rd

iTrader: (43)

And speedometer seems to be accurate?

How's that possible?

Car is a 2000 Trans Am, but has a 2002 Silverado ECU due to being a Turbo 6.0/4L80 swap.

The car is a new acquisition, and needs some tweaking, no doubt, but while looking through the tune on my HPTuners, I see 2.73 as the gear selection, but the car has 3.73's...Transmission shifts as commanded, but as said, needs some dialing in to be to my liking...

How can the speedometer read accurately, as it is setup now?

Any ideas?

dw456post

They probably adjusted the trans revolutions/mile to adjust for it. If it had a 30" tire and now you have a 26", that could make a difference also. Or to make it easy, they just changed the gear ratio to match the speedo. Its hard to tell if you bought it from another person. You will have to do the math to figure it out and do it correctly.

rel3rd

iTrader: (43)

You just made me think of something...

I wonder if because it is a TRUCK ECU, it has/had the gear ratio formulas taken off of a TRUCK sized tire? I think my Silverado references a 30.87" tire as "stock"... I'll have to look at it again, and compare the numbers to my (coincidentally 2002 as well) Silverado.

You may be right about them simply changing the ratio until the speedo matched closer, and then called it a day.

Thanks for the reply.