Engine/Transmission (1998.5 - 2002) Typical performance for TC lock up?

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trying to find lost mpg on a new truck!

2001 3500 4x4 ctd dually!

On the highway and other slower speeds it seems like the TC is unlocked alot! for example at 70mph rpms are 2000 if I let off the pedal rpms decrease to about 1500-1600 and if I re apply the pedal it is very soft with no real speed increase until 2000 rpm! I just relearned my apps and it is now different but not better! Before the apps reset I could release pedal at 70mph and 2000 rpm the revs would fall to 1500 and if I re applied pedal the tc seemed to stay locked and give me a locked speed increase?

Any thoughts on how this should perform? I have only had this truck 1 week so I have no history to compare! I am seeing 13 mpg and my friend is seeing 15. 5 and 20 highway! I think my truck is a little off!

Thanks for any help!

 

[JoshPeters]

At 70mph 2000rpm is normal for 3:54 gears. If you want to really see what the TC lock-up is doing... . Cruise down the road and lightly touch the brake pedal, just enough to actuate the brake lights. The RPM's will flair up to where the TC is unlocked. When you back out of it and it holds at 1500-1600 that is just the small ammout of engine braking you can/will acchieve through the fluid coupling in the converter.



Hope that helps a bit,

Josh

 

[hdtrukn]

Could be a dirty MAP senser or a bad injector.

Do yourself a favor, pickup a set of 275RV injectors about $250 and about 1. 5 hours to install. You will see 3-5mpg increase.

Just my thoughts