ChrisM55

After about 5K miles and about 1K towing my camp trailer I have a few observations and a couple of questions to see if mine might be acting up.

1. between 55-60 it HATES 6th gear!! On the way to Oregon I let it do its own thing for a good portion of the way. Ran right at 1500 RPM and had a horrible drone. Kinda sounded like my air compressor was coming on. As soon as it shifted up it was gone.
2. My milage up was about 9.8-10 and when I left it in 5th gear it went up to 10.4. locked in 5th my rpm was right about 1800 which seemed just right. I know I could have sped up but speed limit in Or. and Ca. is 55 and I can't afford tickets.

Now the question. Every once in a while it seems like it will forget what gear it is in and shift up and down a couple of times. It is always unloaded when this happens and seems to be around 57-60 mph. Also it will sometimes buck a few times at that same RPM. Has anyone ever had this happen??

Over all I love this new trans and the tow-haul is awsome!! It is like having 2 completly different tranny's! Add the ex. brake and WOW!!

Thanks
Chris

motobuffy

mine seems to like 1800rpm for cruising as well, both from a performance and mileage aspect. As to the erratic shifting, nothing like that here!

Kman9090

I was just reading out of curisoity but only 10mpg? Holy crap how do you afford that? Even the hemis will get 12mpg.

GrandpasRam

Not towing camper trailers through the mountains they won't. He was towing, and considering it was in the mountains, that is probably reasonable mileage.

ChrisM55 - 1500 RPM while towing OR empty is not what these trucks like for a cruising RPM, it seems too close to the starting range of the torque band. Especially when towing, they seem to like 1800 RPM much better for a cruise setting, and mine likes 1700 RPM running empty. As to the shifting, if you're trying to run right at the RPM where a shift up/down would occur, any auto trans will try to shift when the load changes like going from flat to uphill, etc. Keep the RPM up a bit and I'll bet you don't get the funny shift any more. This may sound couter-intuitive, but when towing a load the engine doesn't have to fuel as heavily to hold the speed at a little higher RPM (middle of the power band) as it does at lower RPM (lower part of power band); that's probably why you're mileage improved when you went back to 5th gear lock at that speed. When I was doing the towing break-in on mine, I noticed that it like 5th gear better and got better mileage with it at the 55 - 60 MPH range, and it didn't really like 6th (for cruising) until 65. Here in the Dallas Texas area where I live, there aren't many hills, so I was getting 12.9 MPG with the 5th wheel trailer in my sig. After the towing break-in, I've found that 70 - 72 MPH is where Mine likes to run in 6th, which is about 1750 RPM - at that setting I get about 11.5 MPG - that is about 1MPG better than my old '05 got doing the same. Considering you're in some mountains there 10.4 is very reasonable.

Zarthur

I shift mine in to 6 gear on the shifter, keeps it from hunting for it.