RAM 1500 Diesel Forum banner

can someone explain regen frequency and how it may affect mileage

6K views 13 replies 8 participants last post by  Bounty Hunter 
#1 ·
Ok here goes

I use my truck to commute to work 37 miles each way on relatively flat two lane highway never breaking 60 mph. I work 3 on 4 off 4 on 3 off.

I hand calculate each fillup and have typically seen 22-24 mpg. I have a crew short 4x4 3.55 with the 275/65/20 toyo at. And I calculate the difference in tire size as well

When its all said and done my hand calculations come out very close to what the trip meter says. Close enough that I believe the instant read to be fairly accurate which is where my questions comes from

I recently started driving and not letting it shift into 8th gear as I tried it a few times for kicks and I ultimately feel as though it was often lugging when it would go into 8th and I also figured that 7th gear with my taller tires at those speeds couldn't be a whole lot different than a 3.92 truck in 8th gear. Low and behold I see much more consistent 26-31 mpg readings on the instant read where before I would see 22-25 plus its less shifting on the trans. So I can only assume that when I am on that same stretch of highway and my instant read is 21-22 I am in a regen?? And this adds up to where I could or would see this about every other trip to work about every 80 miles

Does any of this make sense?

I am totally onboard with getting a GDE but I like many others are still waiting out the EPA situation. I guess I am just trying to understand my truck a little bit more is all thanks for any incoming information
 
See less See more
#3 ·
So the constant regens are what seems to be holding my mileage back the most based on my driving style/environment

IF this is the case I should think that a GDE tune would yield some good MPG increases over what I am seeing now. Probably not 30+ but should get me back up north of 25
 
#4 ·
I have a very similar commute. Prior to GDE my regens where between 80 and 150 miles. After GDE they are 650 to 750 miles. I see a 2 to 3 mpg drop during regens. So I agree you are on track.

Sent from my SM-G955U using Tapatalk
 
  • Like
Reactions: RandyF
#5 · (Edited)
Another way to look at it, on road trips in my truck the trip average is usually cut somewhere in the 1-2mpg average during a regen. Thats using a bunch of extra fuel. As stated stock I would see a regen at approx 100 mile intervals and with GDE on the highway they are usually somewhere north of 800+ miles. So you have to figure with the stock tune your using a good bit of extra fuel over the course of a tank of fuel.

IF you average say 600 miles to a tank thats 4-5 regens with stock tune and less than 1 with GDE
 
#8 ·
During a regen in my Tradesman...it displays on the readout that Inam going through one and the filter level. Took about 15 min at highway speeds to get through it.
 
#9 ·
During a regen in my Tradesman...it displays on the readout that I'm going through one and the filter level.
That only happens when previous regen attempts have failed and the the DPF level has gone over the 80% level. Normal active regens start about 65% and you'll won't see a notification unless you use a third party monitor. Many people don't see the factory regen notice.
 
#11 ·
I am about 45-50 miles each way but typically see higher speeds. I haven't bothered to check to se how much my instant MPG drops during a regen, since I monitor with Torque Pro.

My current average for regen distance is 325 miles stock.
 
#12 ·
KISS...

Since during a regeneration raw fuel is dumped into the exhaust to burn at the DPF, it's not powering the engine. That means the mileage has to go down as that fuel during regeneration is wasted.

Just did a rare run of 230 miles today, mostly on Interstate doing mostly 80 mpg. 45 minute stoppage for a wreck during return. Got home and looked at one of the digital monitors I set when I left. No towing is what interested me to do this.

28.5 mpg showing at return. With GDE, pretty typical. No regenerations during that run either. My UltraGauge tells me so.
 
  • Like
Reactions: RandyF
#13 ·
update

SO after about 3 weeks running my 7th gear experiment it seems to be working minimally. Last fill I was up 1 mpg. I know its minimal but in theory if I do not allow it to run in 8th the engine will run a little harder cleaner not lugging so less likely to add soot to be regenerated right? so fewer or less often regens
 
#14 ·
The factory tune uses unnecessary injection events to smooth out the engine and make it less 'diesel' like. This is the reason for the large amount of soot generated, as it's unburnt fuel. This will happen the same regardless of gear or RPM.
 
  • Like
Reactions: 97hmcs
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top