6.7L Cummins Forum

I have noticed something interesting about the J35 update that my insight gauge help discover.

My truck is a 2008 3500 dually (in california) w/4.10 rear end and auto 6 speed (make we are on the same page) I have an edge insight gauge setup and one screen has setup for monitoring dpf pressure, dpf trigger, cat sensor and regen status. I run with the EGR disconnected.

With the EGR disconnected, J35 flash in place, on my truck DPF pressure was rising. Regens where very sort, about 2 minutes and turn off. DPF temp would get to 1100 and I could hear the extra inject cycle at exhaust stroke but not run for any length of time as before.

The J35 flash raises the trigger to 5.9, I was a 11 and still rising ..... Nothing to be concerned about, I had a very long way to go before problems and the truck is running great, no performance issues, mileage good ..... But it got me thinking, especially hearing on other forums the problems people where having and folks with completely stock trucks having no issues

So I plugged the EGR back in, cleared the codes, and went for test. Regen kicked in a couple minutes and insight showed it go off again in a 5 minutes. Yet the temp stayed at 1100 and when about 10 minutes, pressure started dropping. 20 minutes later, dropped to 5.2 and it turned off and temps went back to around 725 at 70 MPH.

Here is what I found on my truck, J35 changes a few things .... 1. the PIDs seems to be different, SOOT and SOX regens seems to be swapped. 2. J35 flash will not work correctly unless EGR is working. Subroutine in the code sees EGR error and short cycles. 3. my mileage with J35 and EGR working or not working does not seem to change .... still average around 14.5 combined. I do not know if #2 was intentional or a bug ..... knowing that its no secrete about the EGR, cummins/dodge may have used this a right time to insert a trap ..... If true, its an expensive one for the uninformed owner !

This info is based on about 2000 miles of usage with J35 flash in place. Still investigating and testing, but here is what I found so far. The edge insight has got to be the best around without keeping a laptop in the truck and special software running all the time.

Hope this helps, those of you that have J35 in place and run with EGR off, heads up. Depending on locations, truck setup, things may vary.

Cheers.

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That's a great observation. I recently went to Colorado for vacation and we took our 5th wheel. I average since I have towed this trailer 9 to 11 MPG and have always had the EGR plugged in.
I thought since it was about 2800 miles round trip I would have it unplugged to get better mileage. Well, I did not get better mileage, we check it at every fill up and it remained 9 to 11 MPG.
The only time I get good fuel mileage is when I am not towing or driving and my wife drives. She can get 25 MPG out of my truck, she did 600 miles on 1 tank of fuel and we were not on empty. The best I get is about 17 MPG on the highway.

Thanks for the heads up.

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2008 Dodge 2500HD 6.7L 4X4 Laramie
Edge insight, Amp tailgate step, 4" Boss Bars, rear air bags with compressor, spray in bed liner

Whats your rear end ratio (3.73) ?

25 ... Holy cow ! Are you sure she's not sneaking fuel into the tank when you are not looking

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Yes 3.73 I know it drives me crazy but then I think how much i'm saving and I let her keep driving.

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2008 Dodge 2500HD 6.7L 4X4 Laramie
Edge insight, Amp tailgate step, 4" Boss Bars, rear air bags with compressor, spray in bed liner

The same happens to me. I have 3:73 and standard trans. The wife can get 19 and I'm stuck in the 13-14 range.

This is dang funny.

If my wife drives, I all get is serious chest pains, more white hair, and my life flashing before me !!

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