Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 03-10-2016, 08:39 PM   #15
Senior Member
G Schulz's Avatar
Join Date: Oct 2014
Posts: 119
Originally Posted by jharrell View Post
They do different things, DPF is for soot, DEF is for NOx.

They have a relationship in that for an engine to have met NOx emissions up to 2010 without DEF it needed more EGR to run cooler, because heat and pressure is what creates NOx from air. However when the engine runs cooler it creates more soot causing the DPF to need more often regeneration. So DEF helps reduce regeneration indirectly only because the EGR can now be reduced increasing temps, which also helps mileage and power. It doesn't necessarily change how regeneration is done, only how often it's needed.

For 2010 emission engine makers realized they couldn't meet the tougher standards without DEF, they tried everything, Navistar really tried and failed. EPA doesn't care how you get emissions down, just so happens DEF is the only viable way to get NOx down right now. Volkswagen got caught tweaking EGR which reduced power and mileage but only while testing instead of going with DEF, then on the road it ran hotter but no DEF, so it put out 40 times the NOx.

Here is a diagram, notice how the DEF system is after the DPF:

Attachment 121098

Thanks for the info on emissions. You do know your emissions. I didn't know DEF engines used a DPF as well. I thought the use of DEF eliminated the DPF.

2009 Safari Cheetah 40'
350 HP Cat
2014 Ford Focus
Air Force One

G Schulz is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 03-11-2016, 06:49 PM   #16
Senior Member
lanerd's Avatar
Tiffin Owners Club
Join Date: Apr 2009
Location: Oregon Coast for the summer
Posts: 1,184
You know, I've never measured mine. The DEF is so cheap and I use so little of it, I just don't see the need for measuring. If I'm doing a lot of traveling, I'll keep it about 3/4 full....if I'm setting for a long period of time, only about 1/4 full.

In any case, I guess i can say....who cares?

Ron, Sandie, and Maggie May
2013 Tiffin Phaeton 42LH
2011 GMC Terrain SLT-2
lanerd is online now   Reply With Quote
Old 03-13-2016, 02:00 PM   #17
Senior Member
Winnebago Owners Club
Freightliner Owners Club
Join Date: Nov 2009
Location: Olympia WA
Posts: 131
I asked the original question since my consumption seems high compaired to what the dealer and Cummins says 2% and wanted to know if I should have it looked at next time I take it to Freightliner for service.
Thanks to all the replies.

2012 Journey 36m
erstanfo is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
2015 London Aire, DEF consumption Biverson Newmar Owner's Forum 12 08-09-2015 07:58 PM
DEF Consumption slabman Newmar Owner's Forum 12 11-24-2014 03:55 PM
How is the MPG (Fuel consumption) with your 36LA ?? peprous Tiffin Motorhomes Owners Forum 12 11-16-2014 09:21 AM
DEF Consumption Rate gMw Cummins Engines 19 06-12-2013 02:16 PM

» Virginia Campgrounds

Reviews provided by

Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities

Copyright 2002-2015 Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 05:18 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.