dicknkay

This weekend I'll be traveling on a road that has the grade that gives me the trouble and will get accurate data on engine performance. Will post this info asap.

my c-9 is 400hp with 1200ft-# of torque. I've talked to Allison before and they feel it's an engine problem. For some reason it will not do any downshifting on the 7% type of grade until under 40 mph.

It's been a while since I've had a steep enough grade to cause the problem but I believe that rpm went as low as 1500. On all other hills the shifting works great. I lose only 1 to 3mph before rpm increases to keep climbing the grade. There are no codes in the TX.

My shift pad is a single window. The problem has been going on for years and no one can fix it. The closest hill that will cause the problem is over 1 hour away so it is not easy to get a tech to spend about 3 hours or more to hook up a computer and take a ride with me. To clarify what is happening: Traveling at 65mph with cruise control on, rpm about 1750. Start up the very step, long grade, about 7%min. Speed will drop quickly while rpm will drop but no shifting occurs until speed goes below 40mph. If I arrow down while speed is dropping the TX will not down shift until around speed gets to under 40 mph and 2nd kicks in. I then start to arrow up but I can't build up any speed until the grade starts to level out towards the top of the hill. I've lived with this since most of the time the hills are no problem EXCEPT for the 7% or better grades. But, it annoys me to no end knowing that something is not right and no one can find it. Thanks for your input

2005 Country Coach pulls fairly steep grades OK. When doing 65mph the engine will increase rpm when speed drops about 3mph but on very steep hills will not downshift until speed drops under 40 mph. Down shifting manually does not work either until 2nd gear. All tests show everything OK. Boost pressure, fuel pump pressure,etc. all where they should be. Allison says it's an engine problem. The engine guys can't find anything wrong. What are they failing to check?