Slipping between gears?

The transmissions behavior is heavily dictated by the programming in the Trans Control Module. Both my engine and transmission are tuned, and the tuner (GDE) went through a few iterations of transmission calibrations. The original settings they sent had it shifting too firm, it felt like a dump truck, coming to a stop it dropped into 1st with a notable thud. Definitely no "mush" going on there. Later revisions were more civilized, it turns out that the transmission's "tolerance" can vary, so the same settings will be a bit abrupt in a "low tolerance" transmission and a little soft in another. Evidently my truck's tranny is a "low tolerance" number.

I theorize that GM made the stock programming "soft" so no transmissions would be rough for the end users, but that leaves a lot of room for improvement for any individual transmission.

After tweaking mine with various tune files, I finally found a combo that works really well and does not excessively slip. Even my tweaked setup will slip a little and be lazy if you feather the pedal and take off really easy though. Accelerating briskly seems to work better, feathering the pedal leads to a lot of slipping/flaring in the transmission. No need to floorboard it, but feeding the trans some torque seems to have it shifting better and working as good as it can. I recall my stock trans programming had a really slippy "dipsy doodle" 3rd to 4th shift no matter what I did though.

On a somewhat related note, there are plastic panels that block off the lower portion of the radiator where the trans cooler lines come in. I removed these with no apparent issues with the trans or engine temps even in winter - the trans seems to run about 15 to 20 degrees cooler per the DIC, running in the 170s instead of 190s in ordinary use. I have no idea why GM put those on there, they are not present in the gas models. The panels can be accessed through the grllle and yanked with a long needle nose pliers and pulled out the soft bottom rubber seal under the truck without taking anything apart.

bigoilbob said:

Would you please expand on your trans tune? I read most new posts, but if you have already done so, just tell me and I'll find them myself. I am 180 out from you on engine tunes, but anything to make my trans more durable would be well received.

Thanks

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I can’t say I’ve heard of anyone just getting a trans tune. But, I wouldn’t see why you couldn’t. I have my trans tune through hACKman Customs (sold through American Diesel Power).

I do not recall having a bad experience with my trans before the tune (I did have a slow to react throttle though) but since then, I do know I have no complaints with the tune either. Shifts smoothly at all speeds and under varying acceleration loads (pretty sure my wife only knows how to drive fast while I am more easy going). It may shift more stiffly/ abrupt if you really lay into it, but it should as it’s trying to shift fast to keep up.

What duken4ver said about varying tolerances of transmissions sounds viable, I will say I have only ever had 1 iteration of a trans tune from my provider. It would be worth getting ahold of ADP to see about a trans only tune.

4stroke said:

Can you post a picture for me please?

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Here you go. No need to remove the front fascia, but this photo shows what is going on really well with it removed - the lower 1/3 of the radiator is blocked off by the two plastic panels, and the upper portion of the radiator has the intercooler in front of it.

I was able to reach through my Canyon's grille with a long needle nose pliers, pinch the panel's clip thingies and release them. Then just push the panels out the bottom past the flexible rubber gasket. The whole job took just a few minutes.

Have not noticed any issue at all with warm up of the engine, heater function or trans function this winter, and the trans definitely runs cooler in warm weather - I think 15 to 20F cooler. In frigid temps, the trans will get up to about 140F after awhile, cooler than before, but I don't think it presents a problem. The trans fluid heat exchanger coolant lines plumb into the lower portion of the radiator that is blocked off.

Fully warmed engine temp in warm or cold weather monitored by OBD Fusion on my phone remains steady at around 176F regardless of weather it seems, and the engine warms up the same with the panels off - pretty quickly while driving. The thermostat seems to do a really good job of warming the engine quickly and holding constant engine temps. In really cold weather, it is my habit to crank the seat heater to roast, drive off gently and leave the cabin heat off until the engine warms, which does not take long.

I don't see that the thermostat needs any "help" from these panels and the transmission works fine without them in cold weather. The extra cooling capacity without the panels might come in handy when working the truck hard in hot weather too, particularly for the transmission.

The radiator in our trucks does seem really efficient. Even choked off with all this in front of it, I have never seen the engine run hot, but the trans can easily heat up and get warmer (205F or so just driving around and not towing) than the 175F I prefer under those circumstances. Removing the panels seems to have solved that "issue" and gives more margin before the trans heats up past 240F. I know the trans fluid is OK at that kind of temp, but the life span of the solenoids in the transmission is shortened at sustained elevated temps.