Diesel mileage

[Sludgy]

During a longish trip to New Hampshire to climb Mount Monadnock, my wife and I took the F350 diesel/automatic. For shorter trips we always take her Corolla, but I get leg cramps in it on long drives. I'm already on Coumadin for a blood disorder, so leg cramps are not simply uncomfortable for me. They're dangerous.

Anyway, with the Scangage and careful driving, the beast only got 17 mpg. To say the least, I've been very unhappy with this truck, as my Chevy 5.0 and GMC 4.3 liter trucks got better mileage, without the $5000 diesel option. And I still have 2 years of payments left on this P.O.S. grrrrrrrr

A question: Several companies make diesel ECU programmers that claim more HP and better mileage. Has anybody here used them? Did they help improve mileage?

[Joe Gardner]

My brother had a Dodge Cummins 2500, he consistantly was getting 21 - 22mpg freeway. He had his ECU programmed for better millage when his job location was re-located another 40 miles out of town. From that point out he was getting 24 - 25mpg consistantly. And would only get sub-20 when towing his jeep to Moab.

I think the cost was just north of $100, but for a 3 - 4 mpg increase, it was worth it.

[Joe Gardner]

BTW, that 2500 had 300K miles when he bought it, and 460K when he sold it. He sold it for $1K less then purchase price. IMHO the big reason to keep the diesel around is for the long life of the engine / truck. Resale is going to be worth a bit more as well. Something else to think about.

[Bunger]

Originally Posted by Sludgy

A question: Several companies make diesel ECU programmers that claim more HP and better mileage. Has anybody here used them? Did they help improve mileage?

Yup! Those programmers are awesome!!! I've seen 4-5 people increase mileage a decent amount and also see HUGE increases in power. My buddies dad installed one on his Dodge and said that it paid for itself in the first 3 months, just from the mileage increase! I'd say do a little research and pick yourself up one.

[rh77]

I used to drive an E-350 non-turbo (1996?) which got in the low 20's if I remember right. When the fleet was upgraded to E-350's with the PowerStroke Diesel, the turbo alone sucked the fuel down and generated SO much more power than the standard V-8 diesel -- but more power = more fuel.

I think the secret might be to get a programmable chip or Engine Management System that regulates the turbo pressure, among other factors. You're at an advantage because of the wide range of chips/controllers available. A programmable one could reduce power and increase economy for commutes and long trips, but also be able to switch to a higher turbo psi and fuel pressure for towing, etc.

Also, reduced cruise speed will help with the high drag on pickups.

RH77

[molecule]

mt. monadnock is a nice hike
you can see mt. washington snow peak on any decent day
i've heard with a set of binocs and an illegal night of camping you can see the tip of the prudential building in boston
lol

[Sludgy]

WAI helps mileage, but my turbodiesel has an intercooler that cools the intake! Can I get better mileage by bypassing the intercooler?

[rh77]

Originally Posted by Sludgy

WAI helps mileage, but my turbodiesel has an intercooler that cools the intake! Can I get better mileage by bypassing the intercooler?

The intercooler is there to cool the incoming air so the ECU can use added turbo boost (cool air allows more pressure without the risk of detonation) and more power is available. Warm air would cause the ECU to reduce the boost because of the risk of pinging and detonation, and reduce power. I'm not sure what the limits would be on how hot it would have to get, and if it would dump more fuel in the charge to make it run more rich and prevent catastrophe. I'm thinking that Diesels are susceptible to detonation like gassers. Maybe I'm off. Do you ever get black smoke from the exhaust? If you disconnect the IC as a test and draw in hot engine air, then a trail of black exhaust (as seen in the side mirror) shows that you're pumping more fuel in there. Do you have a ScanGuage or something to monitor engine variables?

RH77

[GasSavers_DaX]

Originally Posted by rh77

The intercooler is there to cool the incoming air so the ECU can use added turbo boost (cool air allows more pressure without the risk of detonation) and more power is available. Warm air would cause the ECU to reduce the boost because of the risk of pinging and detonation, and reduce power. I'm not sure what the limits would be on how hot it would have to get, and if it would dump more fuel in the charge to make it run more rich and prevent catastrophe. I'm thinking that Diesels are susceptible to detonation like gassers. Maybe I'm off. Do you ever get black smoke from the exhaust? If you disconnect the IC as a test and draw in hot engine air, then a trail of black exhaust (as seen in the side mirror) shows that you're pumping more fuel in there. Do you have a ScanGuage or something to monitor engine variables?

RH77

By no means am I a diesel mechanic, but don't diesels run off the concept of detonation? My (limited) understanding is that a diesel is a "pre-ignition" engine, as it does not have spark plugs and ignites the fuel simply on combustion chamber temperatures and compression of the fuel. I have seen turbo diesel trucks run 120+ psi of boost.

[rh77]

Originally Posted by DaX

By no means am I a diesel mechanic, but don't diesels run off the concept of detonation? My (limited) understanding is that a diesel is a "pre-ignition" engine, as it does not have spark plugs and ignites the fuel simply on combustion chamber temperatures and compression of the fuel. I have seen turbo diesel trucks run 120+ psi of boost.

Yeah, I was thinking of that. I guess the turbo pressure and fuel pressure may be the variables of interest. At tractor-pulls or similar events, huge turbos and massive amounts of fuel are pumped: result = LOTS of black smoke. Same with guys who add more powerful fuel pumps to their Dodge/Cummins trucks -- more power and more black smoke. So then it would be reasonable to assume that hotter air does what? I'll have to look this one up...

RH77