TCC won't lock until 45 MPH

[WarWagon]

Any reason GM won't lock the TCC until 45 MPH? Happens on 85 Olds, my 1993 etc. Just wasting fuel in town with the TCC unlocked in 35 MPH zones. Wondering if GM had a good reason to do this other than 'feel'?

 

[NVW]

With my chip mine locks at 35 mph, I don't really care for it as the engine lugs too much. It needs quite a bit of the TPS to unlock the TCC.

 

[tanman_2006]

With 3.73s and a buddy tune I lock at 44mph. Lugs a bit but my truck does good with it. I would like it to lock a bit sooner at times but I'm rarely in town so it's not a big deal.

Sent from: Source Unknown

 

[WarWagon]

Maybe it would lock and unlock a lot? Several places I have flat spots with high engine RPM and low throttle that I just flip the TCC override switch on.

 

[tanman_2006]

Cruising back roads at ~48mph I will lock and unlock on the slightest hills. My tranny is weak (285K) so I just figure thats just going to happen but I would guess if RPM's were even lower I wouldnt hold TCC Lock very well. If it was a 5 speed that problem would be solved BUT I get tired of changing gears all the time with all the driving I do.

This is also the reason I dont drive below 60mph in my dmax, 6th doesnt kick in until ~59mph and 5th doesnt hit until ~52mph so low speed cruising for mpg is hard to do. My 6.5 can do it ALL NIGHT LONG! lol