[railbuff]

Here in Canada, the normal highway speed limit is 80 kM/hr (50mph). I have a 30 mile journey into the local large town by means of a narrow road. I like to travel at just over 80kph so as to keep the truck in overdrive. This way I achieve about 22 mpg. Unfortunately there are usually drivers in front of me that are driving at just below 80 kph and since it is unsafe to overtake, I have to slow down. This results in the transmission dropping out of overdrive resulting in higher rpm and an increase in fuel consumption to about 18 mpg.
My question is: Is there any easy way to lower the speed at which the transmission drops out of overdrive, to say 75 kph (47mph)? As you probably realise, I am not interested in performance, just fuel conservation.

 

[carcrafter22]

Efilive!

 

[Mike L.]

Efilive!

I don't know if that's possible with EFILive but I would not do this if it is.

 

[DURAtotheMAX]

need to keep fluid moving. 1200rpm locked up in 5th gear around town might be getting a little low...

 

[carcrafter22]

oops! disregard then if mike says bad idea then I would listen

 

[Bill 3]

I don't know if that's possible with EFILive but I would not do this if it is.

It is possible with EFILive. You can change the diff gear ratio and it changes everything. I was messing with it last night. I run bigger tires and was interested in getting my shift points and (mostly) my TC lockup back down around 45mph. BUT if Mike L says it is not a good idea, I will change it back.

Mike L, can you briefly explain why? I want to learn as much as I can. I beleive it is a waste to have the TC unlocked when cruising, so I may try to raise the shift point into 5th and/or use OD lockout and lower the TC lockup so it will apply in 4th. ???

Bill

 

[epb091786]

Mike, what is the lowest RPM that you could safely lock the converter at and drive around with it locked up?

My truck will not lock up untill 1500 RPM's in 5th, how much lower can we go?

Bentley

 

[Mike L.]

I would not go under 1500 rpm as the pump speed would be too low.

 

[JoshH]

That's weird. My truck will lock the TC and run in 6th gear down to about 45 mph. I guess I should explain. It will shift into 6th at about 53 and it will hold 6th down to about 45 as long as I don't give it too much throttle. It shifts into 5th at a little over 35 if I'm being light enough on the throttle.