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Forum Index » 2014+ Ram 1500 (DS) EcoDiesel
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Brambles

Joined: 28/07/2015 11:06:22
Messages: 2
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I live in very mountainous terrain of Western Canada.

what I'm experiencing is when decending steep forest service roads in 1st gear, normally in low range, but it happens in high range 1st gear as well.

I stop at the top of a steep section, put in 4low 1st gear and start down the hill, holdback is ok for a diesel but not as good as one might expect with such a steep 1st gear. Once the RPM's increase over 1500 it's like the truck automatically throttles itself up, the fuel consumption gauge shows increased fuel consumption and the truck quickly accelerates forward on its own, at approx 3000 rpm the fueling stops and the truck slows back down.......depending on the steepness and length of the hill I'm going down, it will continue this cycle of self accelerating and decelerating. I have not touched the throttle or brake through this.

It will also do it in 1st gear high range,

This is sporty on dry roads and could be life threatening on snowy or icy roads.

Since you've seen the guts of how these things are are programmed could you offer an explanation of what's happening and if your capable of tuning it out?

It also happened similar in my 2012 ram 1500 hemi but I would have to blip the throttle manually to get it to slow back down. The transmission seems to do a good job of holding and slowing the truck back down...

Thanks

Brambles

Joined: 28/07/2015 11:06:22
Messages: 2
Offline
This truck is bone stock
GreenDieselEngineering
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Joined: 10/07/2009 07:25:47
Messages: 371
Location: Southeast Michigan
Brambles,

The phenomenon you are describing is 100% a result of the transmission programming.

At a certain speed the transmission decides that it needs to close the torque converter lockup clutch, however when coasting like in your maneuver the engine speed is far below the trans input shaft speed (turbine speed).
In this case, the trans sends a positive torque request to the engine in order to raise up the speed before engaging the lock-up clutch. However, the by-product of this is that you feel the vehicle push ahead.

Unfortunately this is not something that we can control with the engine re-programming and is a byproduct of poor transmission tuning by FCA.
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