regeneration... Ye gads?? - Montana Owners Club

richfaa · 10-12-2007, 12:23 PM

Got my high tech guages the other day and have been watching them to learn how this diesel works..Started the thing up in the school lot for the trip home.. EGT reading @ 300 degrees at warm idle ..normal..good..pulled out into traffic and the EGT's started to increase at a rapid rate, Scanned through some other readings and my MPG's are heading down at the same rapid pace. I am in a regeneration sequence.. My EGT increased by 500 degrees..thats right 500 degrees at IDLE..I am looking at 850 and I am not happy... and my MPG dropped to 7.8mpg.. This lasted for over well 5 mins...This is NOT a good thing..has anyone observed this???

Ozz · 10-12-2007, 12:48 PM

I have heard about it, but haven't noticed mine doing it.

gjetzen · 10-13-2007, 02:49 AM

What do you mean by regeneration?

richfaa · 10-13-2007, 03:26 AM

this only occurs on the new 08 and late 07 Diesel engines that must use ULSD fuel..The EPA thinks it is a good thing...me thinks it is a bad thing..

gjetzen · 10-13-2007, 03:35 AM

Didn't answer the question, what is it? This is a term I am not familiar with. Was a auto/ truck technician for 35 years before I retired and I have not hear of it. Of course I'm out of the loop now been retired since 04/06

richfaa · 10-13-2007, 04:33 AM

perhaps this will help http://en.wikipedia.org/wiki/Diesel_particulate_filter Or just google "Diesel regeneration" and read up.. I just drive them..The theory is way over my head.

sreigle · 10-13-2007, 06:32 AM

800 is not hot as egt's go but it is pretty high for idle rpm. I've seen that number at idle when coming to a stop after a long hard uphill run while towing. It takes a bit to cool down. I do not yet have gauges on this Dodge so cannot tell you whether egt runs the same as yours during regen or not.

I read that a regeneration cycle can use up to .6 gallons of diesel but I don't know if that's the max or if that's the norm. I assume that's in addition to what it takes to maintain speed. That sounds like a lot and it will have some impact on overall mileage but I'm finding it is likely a very small impact overall. I recently read an article showing a test between the 5.9L Cummins and the 6.7L Cummins. The 6.7L got slightly better mileage than the 5.9L despite regeneration. So I'm not too worried about it.

So far I've not seen any performance degradation whatsoever during regen. I can't even tell when it's doing a regen unless I'm watching the mileage. But once I get the gauges I'll probably be able to tell by EGT, like you did.

Also, if your EGT probe is prior to the turbo then you've probably discovered it rises and drops very rapidly in response to conditions. I read somewhere that a diesel is running at it's optimum efficiency when the EGT is between 700 and 800 degrees. Of course, that was pre regen engines. Stomp the pedal from a stop and it will likely jump to somewhere over 1000 degrees in a hurry. Climbing hills with Montana in tow will likely show temperatures in the 1000 to 1300 degre range. I try to keep mine under 1200, or did when I had a truck with the gauges. 1200-1300 is ok so long as you're not doing those temperatures for a long time. These are pre-turbo numbers. Post-turbo numbers would be lower and the gauge would react a whole bunch slower.

richfaa · 10-13-2007, 07:50 AM

Steve..When you get gauges installed It will be interesting to see what happens to the EGT's during regen. I also can normally NOT notice the reg process but this time since I was monitoring EGT I knew something was up. I was a bit surprised to see the jump in EGT when in regeration.Wonder what would happen when you are in a long hard pull and the EGT's are up anyhow.....??????

You may also like: