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Discussion Starter · #1 ·
???

Overheat caused by overfueling? Can it be minimized with a "focused tune"?

jeff
 

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At the cost of power yes. I don't think you could impove a stock tune enough to run cooler.
 

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You could copy all the tables over manually, you won't see an improvement in cooling ability in my opinion.
 

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I think we are reaching a bit here. I believe that this is a mechanical issue pure and simple. Be it turbo, heads, injectors, whatever...
 

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Maybe we should look at this topic again. Perhaps from the point of view of looking for anomolies that might explain poor economy. Overheating appears to be related. Datalogging etc. I have a date with a poor mpg vehicle, and am planning to datalog the event. Is there interest, among those that have replied here, to collectively dig into it?
 

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Discussion Starter · #8 · (Edited)
The engine is overfueled to some degree to meet constraints for reduced NOx. Overfueling is a known contributor to diesel engine overheating.


When the GM engineers put together "a tune" - they have to meet both particulate limits (PM) and reduced NOx. Also, when GM puts out a new "tune" - I wonder how much they can change before putting the truck through epa emissions testing again? Are their hands tied to some degree? I did a search on google for "NOx diesel emissions tradeoff" and found some rudimentary info...

Here is a quote from one technical paper...

"...this trade-off occurs because of the contradictory properties of PM and NOx emissions.

Particulate matter tends to form at low temperature and when the fuel is not completely burned, whereas the NOx emissions form at high temperature and when the fuel is completed combusted."

And another from Argonne national labs...

"Therefore, the engine torque and the CVT ratio were both controlled to operate the engine at the most efficient point while satisfying the power demand. However, when the engine operates on its best efficiency curve, it produces excessive NOx emissions."

The full article can be found here :
http://www.transportation.anl.gov/research/hybrids/hybrid_powertrains.html

So the bottom line is that there is power and efficiency to be had simply by ignorring the constraints that the GM engineers were under - namely NOx and PM reduction to meet U.S. federal emissions for the truck.

So it isn't just trading off power to get a cooler running motor - you can trade off emissions standards compliance to get a cooler running motor; Since many here are blocking off their EGRs and most sierra clubber's don't own diesel pickups, I think this is a safe thing to propose in this crowd. :)

jeff
 

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Jeff, I believe you are exactly correct, the EPA certification process, what little I am aware of, is a lengthy and expensive process, not likely to be repeated. Changing the settings that would likely result in emmissions changes, would be tantamount to federal tampering.

Are we ready to conspire to this same level of risk, in order to do what GM contemptuously refuses to do.?
 

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Discussion Starter · #10 ·
Are we ready to conspire to this same level of risk, in order to do what GM contemptuously refuses to do.?
Let me think about it for a second. Yep. :muahaha:

jeff
 

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It's been a while since I was involved in emissions certification, but I don't think things have changed much since that time.

It takes 50,000 miles of typical every-day driving on the proving ground or the equivalent time on test rolls plus multiple emission tests in between to certify a new emissions package. If you average 40 mph including highway and city driving, this will take around 1,250 hours of actual driving time plus the time for scheduled maintenance plus a full 24+ hours for each cold start emissions test to complete. Minor changes can get approval with a 4,000 mile test vehicle. However, if there is a significant change in emissions, a new full blown 50,000 mile test is required.

For truck engines, this test is simulated on an engine dynamometer, so the actual time can be reduced.

These times are in addition to the time required to develop a new package and perform adequate durability testing to validate it before EPA submission can start.

As you can see, it takes quite a bit of time just to get a change out to the public.
 

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Discussion Starter · #13 ·
LOL, I'll get'er done and start a new thread in the EFI section.
Cool - since you brought this thread back to life - you own it now...
:grd:

jeff
 

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Hello, I have '04 2500 duramax That over heated on me pulling a 31ft. trailer I took it to the dealer in vegas . all they could find was small rubber pieces in the thermostat. They replaced both thermostats and I was on my way agian. On my way back from the trip I overheated agian. This time I took to my chevy dealer and they said that its a known problem and they can't do anything about it. Is there anyone who knows what I can do about this problem? I would appreciate any advice. thanks
 

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there is on person with great help working on this problem should have 99%
fix by i think he said before summer waiting on parts states gm is totaly
aware of problem but wont fix its got to do with engine he could tell you
more i think his sig is txchristoheper dont yell at me if im wrong very tired
right now not thinking straight but he is working on fix
 

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So it isn't just trading off power to get a cooler running motor - you can trade off emissions standards compliance to get a cooler running motor; Since many here are blocking off their EGRs and most sierra clubber's don't own diesel pickups, I think this is a safe thing to propose in this crowd. :)

jeff

I wonder is some of the aftermarket tuners take this direction as well. -ie: Edge/BD/Predator/etc, aside from changing timing and duration, and boost, I wonder if they are side stepping pollution control tunes to help increase power and mileage?
 

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I haven't seen where the EGR adds more than 1 degree to the coolant. Its closed way more often than it is open and its coolant flow is small in relation to the overall system.

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