Is The 12V Tune The Best Economy Tune?

[ORDuner]

4th gen trucks are great and all, but the old VE and P-pump 12V trucks Even the VP44 trucks and early (03-06) common rail trucks seem to get better fuel economy.

If I gingerly drove my '02 truck, maintained 62mph on the freeway, let everyone pass me and rarely hit the brakes, I could get 20mpg out of it. Pretty Damn impressive it you ask me! Especially for a 4x4 Auto truck. I wouldn't believe it unless I had done it myself.

Friends of mine have reported similar results from various models of 2nd Gen trucks and another friend of mine reported 20mpg from his '03 dually w/ manual.

I doubt I'll ever get the 20mpgs that I used to, and quite frankly, that was an anomaly. Realistically driving the speed limit or faster, I'd get 16mpg.

The 4th Gen trucks have a weight penalty, because they're bigger. Plus, the engine is bigger. But you'd think with the emissions system taken out of the equation, better fuel injection technology, VGTs and 6-speed transmissions. I think I ought to get the 16mpg I used to. Not the 14 that I typically get on the HWY.

Logically, it makes sense that if you tune the truck like a 12V, you might get performance, including mpgs, like a 12V. Is there any truth to that?

If I eliminate the pre-injection and post injection and well as bump up the timing, that saves fuel right? Is it significant?

Any tips on making a good 12V tune?

TIA!

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[AK Bob]

Interesting question, following!


2014 RAM 3500 (Aisin) 3.73 4X4 Limited Crew Cab Long Bed DRW. Oil Bypass Filter, Fuel Filtration Kit and 50 Gallon auxiliary fuel tank.

Sent from my iPad using Tapatalk

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[TexNeck]

No tips on making one. And please correct me if I’m wrong but My understanding of the pre and post injection is the same amount of fuel enters the cylinder on a given power stroke but instead of it being one large shot (12v) it’s broken up so the noise is reduced and the fuel has better potential to completely burn since it’s being commanded in a smaller dose/shot.

Running DRD 12v vs reg tuning files I did not see any gains worth writing home about besides the fact it sounds great when warmed up. It does run rough (not like old 12v rough- rougher imo) at cold temps and seems like it almost misses so I wouldn’t recommend running it full time in cold climates.

Hopefully someone will be more helpful than me here LOL

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[cumminsdieselfreak]

The pilot injection is removed/modified, it's purpose is to reduce combustion noise. That why you have more noise/chatter on a 12v tune.

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[ORDuner]

At this point I've taken out both the pre and post injection timing. It's surprising me how much you can delete/zero out of these tables and not notice anything.

The engine is noticeably louder. But it doesn't sound like a 12V yet. I'm going to give it some timing and see how it reacts.

1 change at a time...

We'll see how it goes.

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[ORDuner]

I adjusted the main timing EOM 1-9 tables.

I added 2 degrees of timing over the whole table with a max of 24 degrees. The truck seems to pull a little harder at higher RPMs.

I know timing is where the secrets are in the tuning world, so I'm not expecting many people with valuable experience to start sharing. What is a timing table supposed to look like? In my tune, all the tables are identical. As a person that appreciates simplicity, I wonder why they just don't all reference the same table.

It seams like a common shape of the graphical display of this table is to ramp up around the edges at low RPM/MM3s, have a fairly flat middle ground at moderate RPMS/MM3s, and a steep peak. I think the idea is to shift up the flate part of the table so that timing is higher at moderate RPM & MM3 values. Any feedback on that?

TIA

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[ORDuner]

I'm finding out that these are what's known as "Single-Event injection tunes." Lots of stuff to read about when you know what words to look for.

Supposedly there are some gains to be had by pilot injection other than just reducing noise. It pre-heats the cylinder and helps the primary injection burn a bit better. Maybe I'll tinker with it after I get that sweet 12V sound.

Notice how nobody wants that lovely 24V sound that the VP44 trucks made? Hmmm. I actually kinda liked it. Ain't nothin' louder. I wonder what it would take?

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[OneTon]

I get 20mpg regularly on 35's if I keep the speeds under 65mph.

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[16 Cummins]

I had a 2016 with a 68RFE on 35s and got 17-18 mpg unloaded. Never better than 18.5.

I now have a 2016 with a manual transmission and it got 18-18.5 mpg consistently unloaded and 20-20.3 if kept under 60 mph on stock size tires.

It now gets 16.5-18 on 37s.

Both trucks are deleted.

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[timshooter40]

Interesting.

I had a 01 Cummins, 50 over Injectors, built trans, fire punk vp44 injection pump, air dog 165gph fuel pump, fire ringed, mishimoto radiator large core, and 33" tires and consistently got 18 in town and 22 too 24 on the road hand figured.

65mph on highway speeds but I drove normal.

I guess pushed on skinny pedal when needed to pass but right back on cruise after that.

Even towing I averaged 16 -18 mpg.

Route driven Northern Idaho to Northern CA, Red Bluff, CA driving habits contribute to mpg I guess.

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