Horrific Gas Mileage Hemi eTorque

[Hammer1]

I got the TSB's done with my first oil change today. Didn't even have to ask , the service writer said it needed them and it would take a couple hours to update. Got them done and refilled with gas on the way home, will see if mpg increases at all.

A couple of hours.?Each update pays .2

 

[Biga]

A couple of hours.?Each update pays .2

Yea that's what they told me but the paperwork does show .2 each. The gave me a ride back to work and picked me up a couple hours later so I didn't really care.

 

[NoRamForUconnect]

A couple of hours.?Each update pays .2

What is your production date Hammer, and did the mileage get better?

 

[Hammer1]

What is your production date Hammer, and did the mileage get better?

9-18 and no improvement

 

[768mph]

Last week my truck was in for service (oil change and that weird vibration issue) and while there they did three firmware updates. After those updates my MPG’s immediately increased by more than 3mpg. I am now getting the city mpg as was advertised (I do not do a lot of highway driving). I have the e-torque with 22” wheels and 3.92 gear. I forget the exact names of the updates but one was for the hybrid system, one was for the transmission and one was for the pcm. Good luck!

19 Laramie E Torque- build date 7/18

I visited a Dodge dealer here in Houston, (here on leave visiting family), and there were 5 flashes my truck needed. After the dealer in Missouri refused to look at it due to me just “reading updates were available” on the boards.

My mpg went up by 2 combined and hwy. (eTorque Hemi) No more” drag” at low speeds and turns either. Smoother driving and smoother downshifts. Very impressed.

Now 22mpg between 65-70 (tested on 50 mile trip) and 19.5mpg running around town and hwy.

Im pleased now. But I will update when I return to Missouri to see what I get up there. Best was 15-16 around town and 19-20mpg hwy.


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[Jtr]

Had my first fuel-up (only a half tank from the 87 oct dealer probably put in) since picking up the truck last Saturday and I hit the 93 octane for sh** and giggles. Put about 90 miles on and it is now coming in avg 19.3 MPG. Up from 19.1 on the same mileage odo trip. Keep in mind I have not had a lot of city stop an go. I am in the sticks . But I have also not hit a freeway averaging 70 mph either. I am b/w 60 mph max and just stop and go around rural towns between minimal hills/elevation. Since fuel prices are pretty good my plan is to deplete this fuel load as close to empty as possible and hit the 93 oct again and report my manual calculations to ya'll.

 

[pber1]

What kind of MPG?

17-18 on the highway and 11-12 in the city! Before lift I was getting 21-22 hwy couldn’t tell you the city mpg I drove it 500 miles home from San Diego and got it in the shop the following day

 

[kjn86]

Had my first fuel-up (only a half tank from the 87 oct dealer probably put in) since picking up the truck last Saturday and I hit the 93 octane for sh** and giggles. Put about 90 miles on and it is now coming in avg 19.3 MPG. Up from 19.1 on the same mileage odo trip. Keep in mind I have not had a lot of city stop an go. I am in the sticks . But I have also not hit a freeway averaging 70 mph either. I am b/w 60 mph max and just stop and go around rural towns between minimal hills/elevation. Since fuel prices are pretty good my plan is to deplete this fuel load as close to empty as possible and hit the 93 oct again and report my manual calculations to ya'll.

Not sure if this matters, but I had a conversation with the service manager about gas. His take was 87 or 89 only, 89 preferred, nothing more. He said 91+ leaves residue and told me not to use it even if I were willing to pay for it. Don't know enough about engines to know if this is true.

He also said they add some additives for the winter which also reduced gas mileage slightly. Had never heard of this either. This link seems to discuss it pretty thoroughly: http://www.zhome.com/ZCMnL/PICS/winterGas/winterGas.html

 

[Futta112]

About 800 miles on mine.

Just completed an 80 mile trip through rolling hill country with about 12 stoplights . Made a stop for drinks and another for an appointment. Average speed limit was about 50. Used Adaptive cruise . Ended up with 20.3 miles per gallon.

Did you have the updates done? Or was this just how yours is?
My build date on my rebel is the same as yours, and I drive conservative. 15.6 at 1200 miles on truck is the best I can pull. Not expecting 20’s, but 17-18 for mostly county hwy to work and back. My 4th gen with level and 34’s pulled 18’s or better all day.

 

[CouchAssault]

Not sure if this matters, but I had a conversation with the service manager about gas. His take was 87 or 89 only, 89 preferred, nothing more. He said 91+ leaves residue and told me not to use it even if I were willing to pay for it. Don't know enough about engines to know if this is true.

He also said they add some additives for the winter which also reduced gas mileage slightly. Had never heard of this either. This link seems to discuss it pretty thoroughly: http://www.zhome.com/ZCMnL/PICS/winterGas/winterGas.html

on older engines too high of octane can cause carbon build up. It's possible for the carbon to get so bad that premium is required.

Current GM and Ford engines will use knock sensors to know when to advance timing to fully burn higher octane fuels. They've been open with this info. Unfortunately I haven't seen the same from fca.

 

[Gman]

on older engines too high of octane can cause carbon build up. It's possible for the carbon to get so bad that premium is required.

Would love to read some science to back that up. Higher octane means a more stable mixture under compression, but there's just as much carbon in any of the fuel grades.

...and just because it's more stable doesn't mean that it's resistant to burning completely when ignited.

 

[Bram2019]

Generally premium fuel resists ignition knock better than regular fuel. FCA 5.7 engine have 2 knock sensors. One on each side of the block. Basically it detects ignition knock and the pcm reduces timing advance to a point when it does not knock. The pcm has long term and short term memory. So if you add higher octane fuel, it can advance timing further depending how well the fuel resists knock that is currently in the truck. There are limits in the pcm which limit how far the advance can go. It may be only as high as 89 octane will let it go. I don't know. The owner manual recommends 89 octane for 5.7 engines. But can use 87 for which I am sure it slightly retards timing to compensate. It never says anything about 93 premium.
The reason older vehicles may require 93 octance is due to carbon bulidup in the heads which raises compression ratio. If it has no knock sensors so the pcm can't retard the timing. You can get the combustion chamber cleaned to help this. GM had a fantastic spray cleaner which required soak down for the carbon issue.

 

[CouchAssault]

Would love to read some science to back that up. Higher octane means a more stable mixture under compression, but there's just as much carbon in any of the fuel grades.

...and just because it's more stable doesn't mean that it's resistant to burning completely when ignited.

So where does the excess energy go from not advancing timing or increasing compression?

 

[ExcursionDiesel]

So where does the excess energy go from not advancing timing or increasing compression?

What excess energy? 87, 89, and 93 octane gas all have the same BTU per gallon. Gas engines only convert 27% of the fuel's energy to mechanical power. The rest goes into heat.

 

[CouchAssault]

What excess energy? 87, 89, and 93 octane gas all have the same BTU per gallon. Gas engines only convert 27% of the fuel's energy to mechanical power. The rest goes into heat.

I'm not a scientist or an engineer.

I do know that carbon build up from running premium unnecessarilly used to be a thing. Go ahead and Google it. Plenty of stories.

I never said the hemi is susceptible to this issue either. Most modern engines aren't. I've only ever heard about it from old timer mechanics.

 

[alow]

I went on a long road trip and I think the crazy tanks which I promise arent a real thing were me fat fingering the numbers. I get around 18-19 city and 20-22 hwy depending on hills and such. Some of the road trip has very long down hills so I think that plus punching the wrong numbers due to me learning fuelly and being out of reception (so I couldnt do it at the pump and had to remember it) had a lot to do with it.

Can you go in and knock fuelly tanks out? I know the 30 and obviously 40 tanks are wrong.

 

[cmdr bobert]

Just finished up getting all the PCM and TSB updates my truck needed at the dealership.

When I spoke to the service advisor about this issue, he chuckled and said “you’ve got the best fuel economy for the eTorque we’ve seen”.

It definitely made a difference I could measure in the ride to and from the dealer. A 6 mile ride with 1 light and mostly downhill roads got me 18.2 mpg in normal for me driving on the way there (pre update), and using more gas to push back up the hills on the return netted 18.1 mpg post updates.

Anecdotally, I’ve taken the same roads home many times before and would get 15-16 so something is different after the updates were applied.

I’ll run a more scientific test on the highway nearby to compare to my last go.

Hopefully this did the trick.

 

[upstateram]

I'm also seeing around a 2mpg improvement after getting the TSBs, at least according to the computer.

 

[Ortiz7983]

go get it updated. I just had mine taken care of (was getting 13.5 MPG on 55mph highways) After the update i enjoyed 23 mpg.

Here is what they did:
RRT 18-132: 2019 DT Hybrid Control Processor
RRT 18-131: 2019 DT TCM Updates
RRT 18-130: 2019 DT PCM Updates

Is this for the non etorque engines as well?

 

[Futta112]

Is this for the non etorque engines as well?

No. This is for the etourqe


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