DEF
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New User
Joined: Jul 2017
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DEF
Just towed a 12000 lb 5th. wheel 1100 miles from Montana to the Desert, AZ, and noticed the DEF did not move. This included cold temps up North. The 2017 KR Diesel ran like a dream but having problems believing the def gauge stayed at Full. Have been in AZ for a couple of days now and still no movement on the gauge. Is it frozen, I doubt that after 3 days in the desert and warm temps. Was only a very small amount of def required for this trip, I doubt that also.
Please help me with the answer???
Please help me with the answer???
Junior User
Joined: Dec 2017
Posts: 64
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From: NC
I am wondering the same exact thing. I bought the truck about a month ago and it was full of DEF, the previous owner just had the truck serviced and topped off. I have driven the truck probably 1000 miles including pulling a loaded trailer up WV and VA mountains, the DEF gauage has not moved.
Freshman User
Joined: Mar 2008
Posts: 25
Likes: 0
From: Spring, TX
Towed a ~13k 5th wheel from Houston to Central California. DEF gauge stayed put for a good part and then dropped to 1/2. Topped off and not moving again. I'm averaging 9mpg and with cruise control at 68 outside of CA only dropped from 6th to 5th a couple of times.
Cargo Master
Joined: Oct 2015
Posts: 2,745
Likes: 72
From: West Virginia
It's been my experience that less DEF is used when pulling. You have to figure that it is only used during regen, and regen is only performed when the soot build up is enough to require burning off. If you are pulling then the engine is working, the exhaust temp is higher, and the soot is reduced. I used about 5 gallons in 5200 miles, half of which was in front of a camper.
Laughing Gas
Joined: Dec 2005
Posts: 906
Likes: 107
From: Seattle area
It's been my experience that less DEF is used when pulling. You have to figure that it is only used during regen, and regen is only performed when the soot build up is enough to require burning off. If you are pulling then the engine is working, the exhaust temp is higher, and the soot is reduced. I used about 5 gallons in 5200 miles, half of which was in front of a camper.
Nope. DEF use (SCR) and regens (DPF) are not tied together. Completely independent use (yes, they are in the same exhaust stream, but the two are different processes)
Cargo Master
Joined: Oct 2015
Posts: 2,745
Likes: 72
From: West Virginia
You are right. They are. I still suspect the amount of DEF required is going to vary depending on the exhaust temperature.
My understanding of the process may have been flawed, but my observation is not.
My understanding of the process may have been flawed, but my observation is not.
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It's been my experience that less DEF is used when pulling. You have to figure that it is only used during regen, and regen is only performed when the soot build up is enough to require burning off. If you are pulling then the engine is working, the exhaust temp is higher, and the soot is reduced. I used about 5 gallons in 5200 miles, half of which was in front of a camper.
Tuned
Joined: Nov 2016
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From: Saskatchewan
Gary
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Joined: Aug 2015
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I agree that regens happen less often when towing. The higher exhaust temps help keep the DPF clean meaning less regens. They higher temps also increase the usage of DEF though. DEF isn't for regens.
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New User
Joined: Jul 2017
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Gents, started this post, DEF, 2 days ago and thanks for the responses. Still not sure why the gauge never moved during our trip south. I must add that yesterday, while still towing in the desert, which may not have anything to do with the answer, the gauge finally moved to 3/4 full, and at least I now know it is working. I am somewhat still impressed we used less than a 1/4 of the tank hauling a 12K pound 5th wheel over 1400 miles. I have not seen the "orange flash screen" and guess I gotta read up on Regen and Soot filter.
Cross-Country
Joined: Nov 2017
Posts: 65
Likes: 3
where does everyone buy their def? i'm not yet ready to refill, but want to do my homework. i went by a filling station today just to see where the def pump is, and there are several on the large tractor trailer side, not on the passenger car side. several pumps dedicated to def. seems like alot of pumps to me vs how much one would have to fill up the def. unless the over the road guys really us alot. just want to make sure i am putting the right thing in before it's time.