3.0 injector cleaning to increase MPG?

[21JLURDG]

I mentioned to the dealer that I was seeing decreasing MPG on my 21 JLURD, and he suggested injector cleaning at ~$300 at the next oil change. I normally take the dealer's suggestions with a grain of salt, but I'm hoping some of you have informed suggestions.

Stock, I was getting ~25-27 MPG.
~12,000 miles in the summer of 2022, I added a lift and 37s with no gear changes. With the speedometer adjusted, I was seeing ~23-24 MPG.
~16,000 miles/Fall 2022, I had added a full set of skid plates (i.e. belly, diffs, shocks) and front axle truss. I didn't really pay attention to fuel economy at this point, but I'm estimating ~22 MPG.
~18,000 miles/Jan 2023 I took a 3000 mile trip that averaged ~18-19 MPG.
~21,000 miles/Feb 2023 took a 700 mile trip that averaged 17 MPG.

All these long trips tend to be at about 75 mph and cross mountain passes. Occasionally I use 5% biodiesel. I use Hotshot's Secret EDT every fill up.

I know I should expect some MPG reduction with larger tires and slight decrease with winter blends, but my biggest concern is what appears to be a consistent drop in fuel economy. Any thoughts on what may be the reason and/or corrective actions?

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[DGT]

I have a nearly identical setup as you do on my 22 JLURD. I average 21 mpg on varied driving, including a recent 2400 miles trip to Baja, MX. I've surmised that 20-22 mpg is "normal" loaded up like we are weight-wise.

BG245 diesel fuel system cleaner ($40 on Amazon) is excellent for cleaning your injectors, but I doubt that is the issue. 17-19 mpg does seem low if it stays that way or continues lower. I'll keep watching this post for updates.

 

[21JLURDG]

BG245 diesel fuel system cleaner ($40 on Amazon) is excellent for cleaning your injectors, but I doubt that is the issue. 17-19 mpg does seem low if it stays that way or continues lower. I'll keep watching this post for updates.

I'll try BG 245 and see if it makes a difference, then post any results here.

BTW, it looks like we spent some time together in the same general area last month. I didn't notice your Jeep, but maybe you saw mine. It tends to scream: "hey, look at me!"

 

[DGT]

I'll try BG 245 and see if it makes a difference, then post any results here.

BTW, it looks like we spent some time together in the same general area last month. I didn't notice your Jeep, but maybe you saw mine. It tends to scream: "hey, look at me!"

Yep! I did Wayne's World and Fault Line at Sand Hollow. Had a great experience at the Winter Jamboree. I only saw one other diesel there out of the hundreds of Jeeps. But did have a few negative comments regarding the diesel from old timers.

I hope the BG245 works and look forward to hearing what's up with your mileage.

 

[ChuckQue]

I know you said you use EDT but what about Extreme every 5-6k miles?

 

[21JLURDG]

I know you said you use EDT but what about Extreme every 5-6k miles?

I'm not familiar with it but it appears to be a simple injection cleaner to add periodically. If the BG 245 makes a difference, that means I'm getting dirty injectors with using just EDT. I'll consider using a cleaner such as the Extreme on a regular basis.

Does anyone have opinions on bottled injector cleaners vs. a professional injector cleaner done at the dealer or any professional automotive shop?

 

[Shibadog]

I’ve ran diesels for decades. Currently have a 3.0 Ram EcoD and a 3.0 Touareg. I run Power Service through mine occasionally, gray bottle in Summer, white bottle in winter. I probably treat the fuel every 4 tanks or so. As of today, both vehicles, one with 110k and the other with 80k are still delivering basically the same mpg’s as when new. For what it’s work, my Ram has ran a Green Diesel Engineering tune since it had 15k (its at 80k now). Tune gave a nice kick in power/torque AND about an 8%improvement in mpg’s. Best $$ I’ve spent on a rig.

 

[ALeeL]

Every vehicle I have ever owned always got worse fuel economy during the colder months due to increased air density of colder temps. It is worse for vehicles with higher drag coefficients. My BMW 328d diesel has a drag coefficient of .28Cd and I generally see my mileage drop from 48 mpg to 45 mpg (-6.3%) during the winter months. My Ram 2500 diesel truck has a rage coeffect of around .41Cd and its mileage generally drops from 17.5 mpg to 15 mph (-14.5%) in colder temps.

I live in South Texas so I don't get that cold for too long and those in colder climates may see a more significant drop in mileage.

From what I have read, the JL's drag coeffect is even worse than my truck at .45Cd so I can see it's mileage dropping around 15% to 20% depending on how cold it gets in your area. That drag coeffect gets worse the higher your rig is and the wider your tires are.

 

[21JLURDG]

Every vehicle I have ever owned always got worse fuel economy during the colder months due to increased air density of colder temps. It is worse for vehicles with higher drag coefficients....
From what I have read, the JL's drag coeffect is even worse than my truck at .45Cd so I can see it's mileage dropping around 15% to 20% depending on how cold it gets in your area. That drag coeffect gets worse the higher your rig is and the wider your tires are.

I can see colder (hence, denser) air increased drag, but I would think there would be some offset from denser air entering our diesels that thrive on colder air.

I do like the discussion of Cd for our vehicles. It's been a long time since I've heard anyone use this technical term (drag coefficient) for aerodynamic drag. To get total aerodynamic drag (ignoring turbulent, boundary layer, etc.), you need to multiply the frontal area by the Cd. I have no idea how the frontal area of trucks compares to a Wrangler's

https://www.carsales.com.au/editori...ings-about-new-wrangler-worth-knowing-110027/ : "Jeep is very proud of improving Wrangler’s aerodynamic efficiency by nine per cent to a still brick-like 0.454 coefficient of drag."

 

[grimmjeeper]

Density of air doesn't help engines with turbos as they operate off of absolute pressure. The turbo is adjusted to keep bost at the same level.

Higher air density only helps naturally aspirated engines.

 

[NickJar]

Yep! I did Wayne's World and Fault Line at Sand Hollow. Had a great experience at the Winter Jamboree. I only saw one other diesel there out of the hundreds of Jeeps. But did have a few negative comments regarding the diesel from old timers.

I hope the BG245 works and look forward to hearing what's up with your mileage.

I’m wondering what negative stuff did they have to say?

 

[ChuckQue]

I’m wondering what negative stuff did they have to say?

Nothing productive, I’d wager.

Yes, our engines are “niche” so to speak, but I feel like the majority of diesel Jeep owners are hobbyists who wanted something different and interesting in addition to the advertised benefits of the diesel. That’s just my perspective. I know for me that was a huge part of ordering it. It turns heads wherever I go because out here in SoCal there are Jeeps everywhere, but when I get closer and they hear that diesel clatter they go, “Wtf..?” It puts a smile on my face.

I think the haters look at the quirks and issues this engine has and focus on that while conveniently ignoring the myriad of problems the other engine choices have.

Meanwhile, I’ll keep enjoying the awesome low range torque on the trail, followed by the higher fuel mileage off.

 

[Deleted member 59498]

Probably just negative because they think people give two rat turds about their opinions that no one asked for.

 

[ALeeL]

I can see colder (hence, denser) air increased drag, but I would think there would be some offset from denser air entering our diesels that thrive on colder air.

I do like the discussion of Cd for our vehicles. It's been a long time since I've heard anyone use this technical term (drag coefficient) for aerodynamic drag. To get total aerodynamic drag (ignoring turbulent, boundary layer, etc.), you need to multiply the frontal area by the Cd. I have no idea how the frontal area of trucks compares to a Wrangler's

https://www.carsales.com.au/editori...ings-about-new-wrangler-worth-knowing-110027/ : "Jeep is very proud of improving Wrangler’s aerodynamic efficiency by nine per cent to a still brick-like 0.454 coefficient of drag."

I believe any benefit you may receive from ingesting colder air into your engine would be negated by the lower energy content of winter diesel versus summer diesel. Many refineries mix kerosene in with #2 diesel during the winter along with other additives to keep it from gelling. Regular #2 diesel has an energy content of around 140,000 BTUs while kerosene is around 130,000 BTUs so the more they add, the lower the energy content.

I don't recall the actual numbers because I haven't worked at Cummins for over a decade, but I remember they did a study on most efficient outside temps for diesels. I want to say it was between 40F-70F, and once you start getting out of this range then efficiency starts to drop.

If you like technical data, there was a whitepaper that Cummins released when I was there. It is for heavy duty trucks but many of the same principals apply to light duty applications as well. It breaks down what each factor(aero, tires, gears, etc..) has on fuel economy at different speeds.

SECRETS OF BETTER HEAVY-DUTY TRUCK FUEL ECONOMY

 

[DGT]

I’m wondering what negative stuff did they have to say?

Generally, that diesel engines are not meant for Jeep Wranglers and are worse for rock crawling/climbing than gas. I didn't care enough to ask why they thought that. It happened 3 separate times though so it's definitely the opinion of some that diesels are inferior to gas engines in Jeeps for offroading. Heck, it could even be true! But I'm still very happy with mine and would choose the diesel again if I were purchasing today.

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