Passing at high speeds

[mikeminner]

I recently took a trip with my 03 standard cummins with auto trans. When I tried to pass at 70 mph I found that the Trans. did not shift to a passing gear. I found that it does not shift from 65 above. Is this normal. I recall my 98 did a better job passing.

 

[sag2]

Don't know what axle you have, but try running in third at 70 and check your RPM. If it is close to the governor, the PCM will not let you downshift.

 

[navyramman]

and the cruze control will not go above 85mph.

Greg

 

[TImler]

MMinner- Mine is the same way, just boggs down, won't shift. The turbo winds up a little more but thats it. I agree with you, my 2001 did a better job of shifting. After I installed the Edge and the AFE it did seem to help in this area. Just for your info. .

Tim

 

[BHolm]

Mine is like that too. I have 3. 73 gears and it just hangs onto fourth. I find that it does get rolling pretty good though. It is the big torque that moves it along with less drama than a downshift would give.

 

[JThiessen]

Me too...

I've found that it wont down shift at highway speeds, and it wont down shift while towing at lower speeds. I've found that manually shifting makes it go pretty good though.



I'm just curious if this is intentional (always had gassers before).

 

[Swayse]

I had a Duramax/Allison and that darned thing would always be down shifting, I hated it. It would defuel, down shift, speed up maybe 5 mph defuel and shift into 5th. Felt like a stupid gasser.



I like the idea that it holds OD, perfect, throw a box at it and call it good. But you shouldn't be driving an auto anyway.

 

[Kilby]

I just towed my Jeep and trailer to Sacramento Friday, came back yesterday empty. 80+ mph wasn't a problem whatsoever and the cruise control was working just dandy at 90. Mine never downshifts out of OD (except towing) which is perfect. The engine likes it better down low anyhow. The truck is a SO/48RE.

 

[BHolm]

Swayse, Your take on the duramax/allison is right on. I hauled my Unimog from Atlanta home with the Chevy. That thing wouldn't pull in OD at all. I was getting 5 mpg at 65 mph. I complained loud enough on the Chevy diesel board that I got the attention of Allison. They sent a tech with a laptop and we hauled and collected data. They cam up with a re-flash of the trans computer based on that. It has worked pretty well since.



Still, I think the Chev is going to be replaced very soon. The Dodge is super popular at work. The Chev is getting troublesome and I see leaking injectors in my future if I keep it



Everybody that asks me about these trucks gets the same story from me. The Dodge is the only automatic the "likes" being in OD at low rpms. These are diesles, that is where the power is, that is how they should be set up.



I did try hitting the OD button to make a pass at about 60mph. It worked really well, she got up and went