tnpete

At what RMP's does your 5.9 downshift? And I know it depends on wheel size, Gear ratio, Along with trans.
On my 2000 5.9 24 valve 275HP RV engine. That's found its way into my Chevy Kodiak C5500. It does not downshift until 1400 RPMS. Putting a 16,000 lb 5th wheel camper.
Truck has a 6 speed Allison dual OD top gear is 0.61. Rearend is 5.13's and tire size is 225/70R19.5's. This may be right on the downshift, but sure feels like it should be downshifting to 5th way before the 1400 RMPS and 45 MPH.
Pete

KATOOM

Have you tried adjusting the TV cable?

tnpete

The Allison is ran by wire no cables to adjust that I have found. Also does not matter how hard i press on the go peddle. It will not down shift until 1400. I figure its the trans tune that is going to be the issues.
Pete

KATOOM

Did you do this conversion?

tnpete

No it had 32,000 miles on it when I bought the truck.
Pete

tnpete

Thought of something last night. Don't think it would have any effect on the engine and heat. But I did put a muffler on around that time also. As it had 5" straight to the stacks on it. The muffler I put on claims to not change the back pressure or anything. Just take the droan and loud exhaust sound down some.

KATOOM

Thats certainly a possibility even though I cant imagine that a 5" straight through muffler would add any significant flow restriction. Was it straight through?

tnpete

Yes it was straight through as you can make one for sure. That is why I went with it for the free flowing part.
Pete

KATOOM

Then I doubt its related.

One thing I didnt think about was gauge accuracy. I ran across this years ago when I noticed my EGT's higher than normal. I ran under all the same situations and came to the conclusion that there was possibly something wrong with the gauge or thermocouple. I contacted ISSPRO and they walked me through some diagnostics and sent me some parts including a new thermocouple. After putting everything back together the EGT's regained their normalcy.

Just something to consider as thermocouples do wear out.

tnpete

Thermocoupler is only 14 months old. But I wil be swapping it and the gauge out. Also just a different thought. Could the exhaust brake flapper be closed just a little? Its frozen and has not worked the whole time I have owned the truck. But when the muffle was put on. I check the flapper and it was opened wide open. But may have closed some after that and causing the issues?
Pete

KATOOM

Gosh if the flapper valve was closed I would imagine your EGT's would most definitely be affected. But I'd probably only worry about this if the flapper was no longer hooked up to the exhaust brake mechanism because then it "could" potentially move on its own. Not likely but ya never know.

That said, when the exhaust brake is engaged there is no denying it. If the solenoid ever sticks or the flapper sticks and it happens to remain engaged while the throttle is applied then the EGT's will literally spike instantaneously.

I would probably consider a faulty gauge/thermocouple before I'd assume the EB flapper is partially shut.

But in regards to the exhaust brake, you should most definitely get it working. They're immensely beneficial when towing and simply around town just to take the wear and tear off the service brakes. I'm not sure what I'd do without mine.

gorms

Sounds to me like something is amiss between the TPS and controller, or the controller is stuck in econ mode...or parameters need to be changed.

You were talking about downshifting at 1400 rpm, not degrees on pyro right?

How is downshifting otherwise?