Generic question, generally speaking, when should Over Drive come on? Reason I ask is that my recently rebuilt transmission, running with a Towing tune, OD seems to want to come on around 38 mph which seems too soon. Now, this is without me towing and I turn OD off when I am towing. I left the towing tune on since I just towed last week, and will tow again next week and didn't want to bother with reloading them. And I kind of like the aggressive performance with the towing tune, minus the premature OD.

Is my tune the blame here, rebuilt tranny maybe causing it, or is everything just right? The only reason I have concern about is that when it shifts into OD so early, it kind of bogs a little bit, like a stick shift when you go into 5th too soon. A little extra punch pulls through, but doesn't seem normal.

 

What device do you have for the tune ? and OD should be based on RPM not MPH..

 

I use an SCT tuner with tunes from MPT. Agree with the RPM, and when it goes into OD at 38 I am at 1200RPM. I'll have to doublecheck this morning, but pretty sure I'm well under 2000rpm's when it shifts into OD.

 

What is your tire size and gear ratio? I'm running a 285/70/17 with 3.55 gears and OD usually shifts in around 40mph. Can you adjust your shift points with the SCT tuner?

 

35's with 4.56. The thing that seems different is that I don't recall it shifting like this before the tranny rebuild. I have a query into the tuner and I'm also going to load the stock config as well to see if that is different.