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Towing, Heat and Transmission Life  RSS feed
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yakers

Joined: 13/08/2009 19:10:10
Messages: 7
Location: Pasadena CA
I have an 06 CRD with the F37 service. While I would like more MPG and performance my primary concerns are longevity/reliability especially the transmission. I sometimes tow a 3,000 lb travel trailer. This is well within the capabilities of the CRD. I usually cruise about 60MPH in 4th gear. Works great on the flat and often I get 20MPG towing. But I shift down to 3rd (OD off) when ever going up anything but a small grade. I do not think I have a problem with the engine temperature gauge. The CRD runs cool regardless of the outside temp (OK, it goes up a little when it is 110) but will heat up going up grades. I normally run @ 7/16 of the dial and rarely gone up 1 or 2 markings over half except for when it was 110 degrees and going up the Grapevine. But as soon as I see the heat gauge going up I shift down to 3rd, turn off the AC and try do whatever is necessary to bring it down. I have never experienced the automatic fuel/power reduction or the transmission warning light but maybe that is because I pay great attention to not overheating the transmission.

What does the tune offer to those who tow and are concerned heat, towing and with transmission life?

“There are only two ways to live your life. One is as though nothing is a miracle. The
other is as though everything is a miracle.” - Albert Einstein
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GreenDieselEngineering
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Joined: 10/07/2009 07:25:47
Messages: 374
Location: Southeast Michigan
The tune has several features that benefit towing situations. Here is a breakdown of what we have incorporated into the product:

1. Advanced injection timing and higher boost improves towing fuel economy in any gear, this also keeps the exhaust temps lower.
2. Engine torque limit while the transmission is in lock-up mode to minimize the possiblity of initiating "shudder" in the torque converter. This helps to prolong the life of the TC.
3. The electric fan is turned on when the transmission fluid is above normal operating temps when towing. The top three rows of the trans cooler are exposed to the electric fan in the cooling pack and we modified the tune to activate the fan based on trans fluid temp. This is not active in the production calibration.


Honestly, you do not have to be concerned when the coolant gauge starts to rise, only when it is in the red zone do you need to back off the throttle. The engine is self limiting based on coolant temp. The AC will automatically shut off when the heat load is too great. Check out our coolant gauge temperature breakdown on this forum for the 2005 and 2006 clusters.

We could change the the coolant gauge output that is displayed on the cluster to always point in the middle safe zone unless there is an emminant problem. We have not done this and want to gauge what the owners would prefer. If the gauge is moving toward the red zone when the engine is still in normal conditions it does not make much sense and only leads to unwarranted concern by the driver. What is your opinion about this option?
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yakers

Joined: 13/08/2009 19:10:10
Messages: 7
Location: Pasadena CA
GreenDieselEngineering wrote:The tune has several features that benefit towing situations. Here is a breakdown of what we have incorporated into the product:


Honestly, you do not have to be concerned when the coolant gauge starts to rise, only when it is in the red zone do you need to back off the throttle. The engine is self limiting based on coolant temp. The AC will automatically shut off when the heat load is too great. Check out our coolant gauge temperature breakdown on this forum for the 2005 and 2006 clusters.

We could change the the coolant gauge output that is displayed on the cluster to always point in the middle safe zone unless there is an emminant problem. We have not done this and want to gauge what the owners would prefer. If the gauge is moving toward the red zone when the engine is still in normal conditions it does not make much sense and only leads to unwarranted concern by the driver. What is your opinion about this option?


To answer the gauge change question, I just need to know what is ok on this vehicle, need to recalibrate my eyes more than the gauge.


I'm really glad someone is looking into these issues and boy do I appreciate the gauge heat level display,makes me a bit more confidant that I did not fry anything. I want to develop a strategy to best deal with heat while towing up serious grades. I assume I want the engine at an ideal RPM would that be 1800 to 2000 or is it better to use a higher RPM? And then how to help preserve the transmission which is AFAIK the weak link. I pull a trailer that may get up to 3000lbs. I come across the California central valley (US 5) and it is commonly over 100. Recently it was 110 on the flats (no problem on the temp gauge) and as I started up the Grapevine it was 104. I was in 3rd (OD off) and I turned of the AC while just starting up the grade. The temps did climb more than I had seen before. I recognize this is an extreme condition but one I will encounter occasionally. As the gauge headed over the 3/4 I turned on the heater. The gauge did go up another two markings. There are two truck lanes; one for slow trucks and one for very slow trucks, trailers must use one of them. I started out in the regular slow lane and a truck pulled out in front going very slow so I ended going up in 2nd gear as the was no time/space/power to do anything else. I never experienced a decrease in engine power and the transmission warning light never came on but I was getting a bit worried with the engine temp gauge headed so far north where I never saw it before. On my 98 XJ Cherokee there is an almost instant jump from that point to pure overheat, don't ask me how I know. Anyway it looks like everything worked out fine but I want to have a good plan in place before I do serious mountain grades again. These are such extreme circumstances but its only 20 minutes out of an 8 hour trip, I don't mind going up in 2nd with the heater on if that is the best strategy. But I would like to start out with an ideal RPM and gear both for the engine and the transmission. Fortunately I have never had a shudder in the transmission. The engine fan coming on when the trans heats up is a great idea. Sounds like the tune would provide a bit more power but I still need to figure out the optimal approach to serious grades even with the tune.

“There are only two ways to live your life. One is as though nothing is a miracle. The
other is as though everything is a miracle.” - Albert Einstein
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GreenDieselEngineering
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Joined: 10/07/2009 07:25:47
Messages: 374
Location: Southeast Michigan
How fast were you going up the grade and what did you slow down to? Were you wide open throttle? With a 5000 lb trailer at 110 F we targeted runs at 55mph and settled in around 42-45mph up Baker grade. With a 3000 lb unit you should be able to hold 55 (we just push it to the floor with AC on until it shuts off on its own and keep going, the speed will gradually slow down until stabilization is found). Sometimes the trans will downshift to 2nd' if speed drops too much (used only during towing), it should pick up speed in that gear or maintain. With 3000lb or more we would recommend O/D off driving if the transmission keeps shifting up and down, 3rd lock-up keeps the mechanical fan spinning at the optimum speed for air flow through the cooling stack operating in high ambient temp/altitude conditions. Do you use trailer brakes? Definitely recommended on the KJ to help keep the best stability.

With a beefed up torque converter and tune to hold lock-up at peak torque, it might be possible to hold more grades in 4th or 5th lock-up in normal towing. This would improve fuel economy and ride smoother.

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