I would rather have a good working EGR system than have to put DEF in there all the time.
We all have to change our oil when the time comes up.

 

Except for a few unfortunate owners who have had a NOX sensor calibration issue, the DEF usage and subsequent refills have been a non-issue. The cost of the DEF is less than 1/4 cent per mile. The cleaner running engine also gets great fuel mileage. The far fewer EGR events coupled with the new design has allowed many to run well over 7500 miles between oil changes.

You will be hard pressed to find anyone without the NOX sensor issue that will complain at all about the DEF. When the programming fix gets installed in a couple of weeks, the NOX guys will also be happy.

Regards

 

The worst I have heard is about 3000 mi. between fill up with extensive towing. Not my idea of inconvenience. I respect your opinion though. I just have trouble wrapping around the wisdom of having my engine burn 25-30% of it's own exhaust at high power settings.

IMO opinion this was a factor in the showing during the Rumble in the Rockies test. While it is a very real possibility that the elevation was above the critical altitude for the Dual stage turbo thus limiting boost available there is no doubt in my mind the throttle plate was being cycled to assist EGR flow.

My WAG,
1. WOT sends the Turbo vanes open for max boost as the truck climbs and the compressor unloads the turbine spins faster, higher flow thru the turbine side reduces exhaust pressure for EGR circulation. The extended wide open throttle is the worst possible scenario for NOX production which the PCM is going to try to combat with EGR and DEF. I would think that emissions will always win over performance and the PCM will position the throttle plate as required to maintain EGR flow further knocking boost and power down. GM figured this out very easily and capitalized on it no doubt.

My 2 cents.

 

If that is true, why was there only 8 seconds difference in the Edmunds 11 mile uphill pull comparison? Pulling that hard for that long of a distance and time would certainly raise egt's to the point where the DEF system is running full tilt. If EGR and DEF are tied together as you propose, the EGR would be cycling at maximum rate as well. The performance shortfall for the Ford was 1% in this comparison. It was much higher in the Rumble commercial.

There are other owners here, Von Overkill is one, that live and operate daily at high altitudes. They confirm that their trucks run much stronger at lower altitudes. If it is just programming and not the turbo choice that limits this performance, it should be an easy fix...but we have not seen an update yet...

Regards

 

Let's just put this into perspective for a minute.

I could argue all of these are sad:

1. Being consistently beaten by a truck with 3 HP less in every towing test done to date

2. 6.4L fuel in oil dilution problems mandating severe service maintenance

3. 6.0L engines with repeated high-dollar failures nearly destroying Ford's warranty

4. Overall diesel reliability being nearly dead least among the Big 3 for the last 7 years until the new 6.7L engine.



My point is that as much as we all love to bash GM and Dodge, nobody hits home runs all the time. Our engines seem to be top of the heap right now, but let's not let this go to our heads here. I could argue that Ford's diesel history is far more tarnished than the other two.

 

I am with Tom here. I have been called the Big Ford Drum and a lot worse at the rv site. I, however, do not bash the other manufacturer's trucks. I do rebut disingenuous owners of OB trucks who post incorrect information or exaggerated claims of problems. After owning a problematic 6.0 Ford, I realize how easy it is for a manufacturer get it's hard earned reputation tarnished. Yes, GM has a similar but larger DEF issue than Ford. I do not celebrate their woes. I have been down that road and it is not much fun. If my posting of the long GM thread looked like "piling on", I am sorry I posted it.

Regards

 

its easy to get an exemption when the government owns the company.

 

Rick,
To answer your question about the Edmunds versus Rockies tests, of course it's elevation every turbo installation has a critical altitude where it can no longer make it's max boost (appears to be about 23 lbs. for us) this is measured by the MAP sensor. Like I said earlier the compressor starts to unload because it just can't physically compress the air to 23 lbs. no matter how fast its spun causes the exhaust flow thru the turbine to go up lowering the exhaust pressure in the manifolds. There is an exhaust pressure sensor in the rt. side feed pipe to the turbo. If you look at the Coffee Table Book and the sensor range charts you will see the difference in the two pressures is pretty steep. Another interesting fact is look at the values for the downstream backpressure sensor post turbo, it's single digits. They extract a lot of work out of that exhaust and the exhaust system flows pretty well even with all the aftertreatment devices.

I remeber the critical altitude on the 7.3 turbo was 8000 ft. btw.

When the turbo compressor can make 23 lbs of boost (and actually more than that down low) it is causing a fair amount of backpressure to do that work allowing the exhaust pressure to be at a value the PCM is happy with for EGR flow rates. The throttle stays open allowing full intake flow, the more air the better the burn for the amount of fuel injected actually helps with NOX production as well. There is a chance they could also be using the throttle plate to protect the turbo from overspeed loading the compressor as well.

I remember reading a comment some where that during one of the comparisons that the GM trucks used considerably more DEF during the tests it may be that their strategy uses the DEF to compensate for the reduced egr flow. Hey it just dawned on me, if they have an emissions exemption how can any test be considered Apples to Apples?

 

Wow, you might be on to something. Makes a great deal of sense. Anyone confirm the Rumble Chev had an EPA exemption?

 

...not likely seeing that the Rumble was last summer and the GM DEF issues began after cold weather. This exemption is quite recent. The GM problem is much more widespread in all manner of scope. Geo-graphic's, temp spread's and truck debilitation issues are much wider than Ford has experienced.

It is too bad that the still rather small sample of trucks from both manufacturer's have had this DEF related issue. The Dodge Boy's would like to think they could make a much bigger deal out of this problem than exists.

Regards

 

Take a look at the tag under the hood Duane posted the exemption is dated 4/10. My motivation isn't to redeem the Ford or bash GM just to understand what be it hardware or software caused the gap.

 

That date was explained on the GM forum. They had to go back to the original production start date to cover any and all trucks that had the issue...just what I read

GM had several re-flashes prior to going the exempt route. They could not prevent the activation of limp mode. This provided a hardship case for owners so the exemption was granted. It is my understanding that owners have to sign a statement that they understand the temporary nature of the exemption and that if they do not return to have the truck re-flashed with the end result solution they have voided their warranty...

Regards

 

I hope they get it cleaned up quickly, the GM folks are as passionate as us and it's gotta be frustrating. There's plenty of room for all 3 brands in the market.

 

I agree wholeheartedly...but don't try to tell this to the "Boys" over at rvnet

 

I agree we need all three to keep the trucks fresh. We wouldn't have a 400/800 diesel if Chevy didn't have some thing that beat the original numbers. Plus the small things like factory tow controller and up lifter switches. I hope Dodge makes a 500/1000 diesel so my next ford can have even more.