While driving on an Interstate Highway during low traffic volumes I try to flow with traffic and stay out of the other driver’s way. Inevitably someone has to block the left passing lane because that is easier for them than moving back to the right lane. In this situation I am not afraid to pass on the right while speeding up to get past. Speed limit in my area is 70 mph. I normally run 77mph. In order to get past the road hogs I have to sometimes quickly accelerate up to 85 mph.

I noticed that if I go to almost wide open throttle the truck wants to downshift and then immediately up-shift. Anyone else noticethis condition? Or is my transmission slipping?

The truck drives/shifts normal under all other driving conditions.

 

This your first vehicle? It is normal for a transmission to kickdown when you put the pedal on the floor.

 

This is how an automatic transmission operates. Same question: First vehicle?

 

in the 60s the 727 would not drop to 2 nd unless you went WOT. in the 70s chrysler put a part throttle down shift in TFs. cant remember when or which spools / springs made this change. these guys can give you the better info. http://www.areds.com/,,,, i have known these guys since the late 60s. an other out fit to check is Trans-Go. hope this helps.

 

I started driving in the early 1970's lol.

However, this is my first Mopar.

The kickdown is expected, and I was expecting it to hold the lower gear, it is the sudden and almost instant upshift after the kickdown that is new to me.

The rest of the story is that I was on a 1,400 mile cross-country trip. On my way South I was towing a 5,000 lb. travel trailer. I only ran 60 mph while towing and was able to run 700 miles in one day. That say's alot about RAM truck quality if you know much about towing.

It was on the way home when running solo that I experienced the sudden upshift situation. May not have explained the condition very well in my post.

 

Still sounds normal. Kicks down then upshifts when it hits a designated RPM or if you lift back off the throttle.


In the old days there was a kickdown solenoid on the carb and it would hold the kickdown until you let off the throttle enough to deactivate the solenoid, regardless of RPM.

 

Yes and No. I would still be heavy into the throttle when it upshifted (almost immediatly) after downshifting. And the RPM's would be steady because there was no time for spinning up. Maybe I should have been using full throttle instead of almost wide open?

Guessing no one else has experienced this sudden up-shifting...

 

I think I've experienced something like that before. Probably just a quirk of the shift logic. That's just software and this situation is probably a boundary condition that isn't dealt with well.

Rob

 

Thanks Rob, agreed must be shift logic (surprisingly fast).

 

I've experienced exactly what you are describing on other electronically controlled automatic transmissions (I don't have a fourth gen RAM), at those higher speeds and near WOT (wide open throttle), the transmission will downshift simply because you are at or very near WOT (which the computer sees as you demanding maximum power, causing an immediate downshift), but sensing no significant load (or real demand) will upshift ASAP as being in the lower gear isn't necessary.

I wouldn't call it abnormal, just a little quirk some autos have at faster speeds and WOT, due to the programming/shift tables. Said quirk may become a lot more prominent if downshifting causes you to come near the upper end of your RPM limit, the transmisison will be very eager to upshift to avoid running the engine at high RPMs (or possibly over-revving) for sustained periods of time.

Hope this helps explain the phenomena.