To OD or not OD

[hammerg26]

Got your attention
I read a post the other day where Thermo stated that the "sweet spot" in the power band for the Expy is around 2000 rpms. During my commute, I have the occasion to be "cruising" at around 45 mph (about 1400 rpms in OD). Any time I have to accelerate, it is not quick... would it be better for MPG and for overall driveability to turn off my OD, or I do I leave the OD on? Or (most likely) does not matter at all...

Thanks.

Hammer

 

[alaskanexpy]

i turn my o/d off all the time (when i put the truck in gear its the first thing i do) unless i'm on the highway 65mph or more for a long period of time. any change in speed causes it to downshift from o/d into 3rd. makes for much better driveablity around town.

 

[saabkid]

just noticed that today. It drives me nuts, OD off from now on around town

 

[1997SCEBFEX]

Always on, less trailering of course.

With regard to mpg, if your commute it totally flat, the 'lie-o-meter' might not show a difference in instantaneous mpg, but would suspect over the long haul that there would be some reduction due to increased rpm not using OD. Sometimes mine will shift into OD as low as 39 mph, others higher depending on the throttle setting, road conditions, and trans line pressure.

PanHandler.

 

[toms89]

I would say overdrive on will save fuel. When the motor is not under load the lower rpms will require far less fuel. Only way to confirm is to go through several tanks of fuel both ways and check mileage.

That's really the reason overdrive was implemented. Fuel economy. Also saves on engine wear. I have a C4 in my mustang (no overdrive) which is great for responsiveness. But as far as fuel economy it sucks.

A custom tune would be ideal in your situation. You can have it wait to shift into overdrive until slightly higher speed and downshift with much lower throttle input. It would be biased towards performance and not fuel economy though to a certain degree it could help with mileage if it keeps the motor from bogging.

Not sure how good the "canned" tunes are as far as shift schedules..

I played with shift schedules a lot on my tune to perfect it to my liking. It makes it much more responsive and seamless in nature.

 

[GAINMOB]

i never have my on...so yall are saying to have it on...so o/d around town and no o/d on highway?

 

[toms89]

i never have my on...so yall are saying to have it on...so o/d around town and no o/d on highway?

I believe they are saying the opposite. O/D off around town, O/D on highway.

 

[Thermo]

Freeway, what Tom said.

 

[hammerg26]

Thermo - did I recall correctly what you stated previously???

 

[alaskanexpy]

I believe they are saying the opposite. O/D off around town, O/D on highway.

exactly, mines off at all times except if i'm on the highway for long periods of time.

i could care less about MPG the driveablity means ALOT more to me.