Wierd Question

[Nice rig]

Ok, I'll try and explain this as simple as possible. My truck has done this since day one of buying it used. If I'm driving down the highway going about 65 and get fully off the gas to prepare to stop, while coasting down and get to about 55mph there is a distinct drop in RPM (a few hundred) and I feel the engine braking me before I even touch the brakes...I can also hear the different pitch in the exhaust. This just isn't the typical smooth drop in RPM because I'm off the gas. If I drive below 55mph it doesn't do it. Not that I'm worried, just curious if this is a built in feature or what.

[Darkanion]

Does your truck have a "tow" mode? If so, it sounds like it is turned on. I haven't checked exact RPM's, speeds, etc., but that 'sounds' like what my truck does when I have tow mode engaged...

[Draenor]

Has the tranny been serviced regularly?

TPS could be dirty, have you inspected or cleaned the Trottle Body?

[Zembonez]

It could also be the computer reacting to the closed throttle. When the throttle is closed, the lockup converter will "engine brake" until it disengges... but upon disengagement, engine RPMs will drop because of the closed throttle position...

 

If it is consistent and does not cause any drive-ability issues I'd not worry over it.

 

But I am a Crazy Clown.

[Nice rig]

It doesn't act like the throttle is stuck open a little or anything like that. I bought the truck w/98,000 on it and have 120,000 on the clock now. It kind of feels like Zembonez mentioned, once the lock up is disengaged (which is around 45mph) everything is good. I'm not worried about it, she is still strong and has been doing this for more than 20,000 miles.