Cruising at about 50 the other day, I look at my RPM... I was about 1750 or so... I give it a little bit of gas without downshifting and the rpms drop to 1600ish... Now, I hit the gas and the RPM drops? Okay?! Normal? Torque converter problems?

 

Your torque converter is in the middle of lockup and coast it's called semi lock up. Lockup happens when you are on the gas calling for power to be transferred to the rear end. When you take your foot off the gas it comes out of lockup and goes into coast for better gas mileage. When the tow feature is engaged the torque converter stays in full lockup.

Now there's full lockup and semi full lockup and no-lockup. The trans can slip somewhat for fuel saving in semi lockup because of torque management in the PCM.
When I'm in traffic (stop and go) or towing I always engage the tow feature for full lockup so as not to overheat the trans or cause un-needed ware. When going up large grades of hills like 5% or 6% and up I lock it the towing feature in. This does two things:

1. Keeps the transmission from shifting in and out of overdrive which is VERY hard on your trany.

2. Next time you are going up a long hill drop into 3rd and watch your RPM's then engage your towing feature locking the torque converter. You will watch your RPM's drop about 200 to 300 RPM's while still in 3rd gear.

This dis-engages torque management which is meant to be there to increase your power band output, and match the trans to the motor to keep the power flowing for optional power. This is a bad idea in MY opinion because it increases ware but feels softer as to increase sales. This is why a lot of flashing companies will remove it. The torque converter does this with magnets.

When no torque management is called for more power is sent to the magnets to close tighter therefore stopping slip. Torque management sends small amount of current to the magnets allowing some slippage. Coasting removes power from the magnets to increase the most slippage (coast when no power is called for* fuel saving*).

So to answer your question, this is why and how it happens. Now the TPS could be out of adjustment or bad. So double check that. Also I assume you have a 5.9L and a 46-RE trans in a 1998 or 1999?

 

Tow button a 1998, 1999 feature only?

 

nope in the later years its labeled O/D off tho or at least mine is but it does the same thing im almost positive

 

I agree with Hydra. In the D or my van I keep it out of overdrive and let it lock the converter at 30mph to keep trans temps down when driving on city streets

 

That's not a tow button, that's an overdrive off button.

 

ya i know but i it does basically the same thing it locks it into gear and locks out the OD mine shifts "harder" when i use it and locks up at 1500rpms going up hill in 4th so it def locks it up more

 

Yea that's what I ment but:

Considering the torque management, it really is a tow button because it does more than just lock the gearing out of OD.

Also by the way it's acting is why I'm labeling it a 1998 or 1999 5.9L with the 46-RE, thats all.

 

BTW<------It might be a good idea to change out the transmission output sensor. But then again what year, motor are we working on? Model of trans if you got it?

 

Sorry, usually don't forget the critical info!

199 5.2L 4x4. I changed the TPS and aligned it to .68V... The best I could get without drilling the brass spacers out... I don't want to jack a new TPS just yet but .68 is close enough. Did this with the old TPS too... So, I guess I will see about the tranny output sensor? Anyone have prices for this peice? Location?