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JMonroe · 05-11-2018, 10:06 AM

We were delayed in leaving Florida this year, in part because of a bad NOX sensor. As the diagnostic codes also said the engine had been "derated" we had to arrange for a Cummins field tech to come to us.

The tech's computer confirmed the bad NOX sensor (unfortunately, it was the one ahead of the turbo, requiring the bathroom floor to be removed for access) and, at the same time, that our ECM was way out of date in terms of updates. He took care of that to, taking us from version .14 to .21.

I can only guess that the update was responsible for a major decrease in DEF use. I have previously complained, both here and to Cummins, that we were using something near 8% DEF to fuel when Cummins says should max out at 5%. With only the one 500 mile trip behind us so far, best I can calculate we were very close to 5%.

Obviously I'll continue to monitor this, but I'm optomistic that our DEF use may have been cut by almost 40% by the update.

WILDEBILL308 · 05-11-2018, 08:44 PM

Quote:

Originally Posted by JMonroe

We were delayed in leaving Florida this year, in part because of a bad NOX sensor. As the diagnostic codes also said the engine had been "derated" we had to arrange for a Cummins field tech to come to us.

The tech's computer confirmed the bad NOX sensor (unfortunately, it was the one ahead of the turbo, requiring the bathroom floor to be removed for access) and, at the same time, that our ECM was way out of date in terms of updates. He took care of that to, taking us from version .14 to .21.

I can only guess that the update was responsible for a major decrease in DEF use. I have previously complained, both here and to Cummins, that we were using something near 8% DEF to fuel when Cummins says should max out at 5%. With only the one 500 mile trip behind us so far, best I can calculate we were very close to 5%.

Obviously I'll continue to monitor this, but I'm optomistic that our DEF use may have been cut by almost 40% by the update.

That is good news, any change in fuel mileage?
Bill

JMonroe · 05-12-2018, 08:08 AM

Don't think update effected fuel mileage, but it was probably too short of a trip to know. Especially combined with the multiple start/idle sessions while diagnostics and repairs were being done (not only for the NOX sensor, but for damage caused by a rat). We also used more fuel in the Oasis than usual due to a much colder than normal winter.

That said, I do think we may be seeing a slight uptick in milage simply due to the miles we've acumulated. We experienced the same thing with our last coach too, especially past 20 - 25k miles on the odometer. On this coach we're at about 16k.

I've never had a complaint about mileage with this coach. We got 7mpg on our very first tank of fuel.

tom chelbana · 05-12-2018, 05:45 PM

On our 18 London Aire with Spartan K3 and new X15 getting about 200 miles per gallon of DEF.

JMonroe · 05-13-2018, 07:46 AM

Quote:

Originally Posted by tom chelbana

On our 18 London Aire with Spartan K3 and new X15 getting about 200 miles per gallon of DEF.

Assuming you're getting about 7 miles per gallon, that would be approximately 3.5%. I'd be very happy with that.

The next couple of tanks of fuel will be a better test. No excessive idling, no use of fuel for the Oasis. I'll be revisiting this in July.

uncnavy2000 · 05-19-2018, 10:55 AM

I just had my 16 coach in for annual service at Cummins yesterday and they updated my ECM as well. Like you, I was way out of date and have experienced high def usage (needed to fill def on every fuel stop, though I do tend to need nearly 200 gallons at fill up time). I'm hopeful we will both see a drop in consumption!

JMonroe · 05-19-2018, 02:06 PM

What kind of coach can you add 200 gallons of fuel to?

uncnavy2000 · 05-19-2018, 04:24 PM

The King Aire has a 200 gallon fuel tank

WILDEBILL308 · 05-20-2018, 08:51 AM

I would be looking at filling at 1/2 tank and definitely before 1/4. I never run under 1/4 tank before looking for fuel.

Bill

JMonroe · 09-01-2018, 07:02 PM

Just an update to my original post.

We just returned from a 3500 mile round trip from South Carolina to New Mexico and back. We averaged 7.2mpg and DEF use comes in just below 5% (4.7).

Seems that ECM update done last April had a positive effect on DEF use. We're now within parameters suggested by Cummins (for the ISX), a lot lower than the 7 to 8% I'd been complaining about.

jd956jd956 · 09-01-2018, 10:07 PM

Hi JMonroe - that is great news. How did you come to get the ecm update? Was it a warranty issue? How does one get ecm updates? THANK YOU, Jeff

jd956jd956 · 09-01-2018, 10:11 PM

Ooooops! Please disregard JM.... Sorry, I failed to go back!
Yet as I type now, how wound one know if they are in need of ECM updates? I am one of those who has never stepped inside a Cummins dealership.

JMonroe · 09-02-2018, 07:25 AM

Normally they would be done during normal servicing.

For decades now I've always recommended that your car be serviced at the dealer, and I feel the same about our coach. Yes, you can get an oil change done for less, but the records won't track and if there is an issue downstream you'll be fighting to prove that a lack of proper maintenance didn't cause your problem- not to mention that the quick change shop isn't going to check for technical bulletins, recalls or do updates.