Mileage down shift time increases

[doc]

We have a 3000 Allison in a 2008 Damon Essence. We recently returned from a 1 day trip to Virginia and then back down through Tennessee across the Smokeys to N Georgia. The fuel mileage dropped from about 8.5 to a little over 7. Coming from Pigeon Forge across to Cherokee, after we got down on relatively level ground on the 4 lane from the Cherokee turn off to Dillsboro, I began to notice the Allison was taking some time to get into 6th gear. We were running about 55 to 60 MPH and towing a Honda Element. We got into Franklin and started down US441 and I was able to observe the tranny a bit closer. Again, it would shift very smoothly (never even felt it change) into 5th. It then would run several miles sometimes before it got into 6th. When we got below Clayton it was beginning to concern me and I would accelerate down hills and then back off on the accelerate, trying to get it into 6th. Sometimes it would and sometimes not. At one time I had a long stretch and had to get up to 75 before it would change.
It appears that it was more slugglish in changing after I had used the engine brake. I am unsure about this since I only noticed this the last 30 or so miles of the trip. I am also unsure where this started since I paid no attention on I-85 and 77 headed to Virginia and headed south on 81. Other than the milage drop off the the seemingly extended time to change into 6th I have no real evidence of anything amiss, but it is bothering me when it does take to long to change up all the way. Ideas? Is this normal or am I being paranoid? When we first bought this thing it did not take that long to change, that I am sure of.

[bdpreece]

Just a couple of thoughts. I am assuming you have a Pac Brake have you ever lubed it? It could be sticking. If you have the Cummins ISL ignore this thought you don't have a Pac Brake. Next thing to try is disconnect the batteries to the coach for about 30 seconds then re-attach. This will drop power to the computer and the Allison transmission will then re-learn it's shifting points with your driving. I am assuming you have checked your fluid level for the transmission. Another thought would be when was the last time you changed the fuel filters? Dirty fuel filters require you to give it more throttle and if the engine does not reach the rpm for 6th gear it will never shift and it will be sluggish.

[doc]

Thanks Brian, won't hurt anything to try the disconnect. Will give it a try. And, it may be just me getting paranoid - but the milage is lower so we'll see.

[Mr_D]

Quote:

Originally Posted by bdpreece Just a couple of thoughts. I am assuming you have a Pac Brake have you ever lubed it? It could be sticking. If you have the Cummins ISL ignore this thought you don't have a Pac Brake. Next thing to try is disconnect the batteries to the coach for about 30 seconds then re-attach. This will drop power to the computer and the Allison transmission will then re-learn it's shifting points with your driving. I am assuming you have checked your fluid level for the transmission. Another thought would be when was the last time you changed the fuel filters? Dirty fuel filters require you to give it more throttle and if the engine does not reach the rpm for 6th gear it will never shift and it will be sluggish.

Some 370 ISL's did have an exhaust brake rather than a engine brake. It depended on what the manufacturer ordered on the chassis.

As to mileage, according to one Cummins white paper it take 140,000 miles to establish a true accurate mileage figure, one or two tanks isn't enough, let alone a few miles.