Ok, I have had this tune installed now for almost two weeks. I have not yet had the opportunity to take my truck out on an extended road trip to test out the MPG Booster. That will come later this year (perhaps in July because of my work schedule). I will try to convey the proper information in a clear manner. Unfortunately, I am not an engineering type of person, so it may not be as well put for some of you out there.
First – the behavior of the truck prior to install.
Initially, I have found our trucks to be a little bit sluggish. I did test drive a 2500 with the 5.7 under the hood before buying my PW and I am ever so glad I chose the PW. The extra size in the engine definitely helps get this monster moving.
The truck had 265 sized tires on it when I took it on my first road trip to Yellowstone. (We won’t get into my lack of research concerning standard PW equipment from the factory) Maintaining at least the speed limit (but never more than 5 over) I was able to average 15.5 mpg for the entire trip. This included towing a car on the way back home. During the tow home, I kept my speed down to 60 mph because of the less than stellar appearance of the towing dolly from U-Haul. My mileage peaked at just a shade over 17 mpg (17.2 I think) and I was extremely impressed.
Even around town, the truck stayed above 14 mpg. But like I mentioned earlier, it seemed to take more time to accelerate to appropriate speeds. For a truck almost hitting the scales at 8000 lbs. I really can’t complain.
Bigger tires = less MPG
We are all familiar with the tire debate on the forum. After much deliberation, I decided on 35” BFG’s. After the install, with great disappointment, I watched as my fuel economy start to take a huge hit. Around town mileage went all the way down to 10.4 mpg! Limited highway exposure saw the numbers climb back to a somewhat respectable 11.5, but gone were the days of my mid to upper teens. It was at this time I began to consider some methods to restore/improve the mpg’s without going back to a smaller tire.
For under $900 I removed and installed a new exhaust system. My around town mileage improved from 10.4 to 11.3, almost a full mile per gallon! Highway travel saw a similar increase, going from 11.5 to 12.3. Personally, I think it was money well spent. Especially since now my truck has a cool lower tone when idling and accelerating.
Tuner vs. Re-Gearing
Both of these options are not cheap. Estimates for my marker saw re-gearing coming in at $1800. Because I own a 2015 PW, a new tuner comes in at $900 from most retailers and $1000 from Sean at Hemifever. Both items will void a factory warranty. After consulting with a few local 4x4 shops here in town, I decided to go with the tuning option. For my purposes, re-gearing without immediately going to a 37” tire was not going to help me much. I went with the Hemifever option to get custom tuning from Sean.
A recap on my mileage before the tuner:
Highway – 15.5 down to 11.5 and then back up to 12.3
City – 14+ down to 10.4 and then back up to 11.3
Now for the tuner!
I didn’t bother running a separate set of numbers with the canned tune from Diablo. I will tell you this, there was a marked “seat of the pants” improvement with acceleration off the line and the shift points were completely different. A day or two later, Sean sent me my custom tune and, in short, what a rush!
This truck absolutely screams in the upper range of the rpm’s. Just so I don’t get in trouble, I have yet to see what it tops out at. Under hard acceleration, the gears have a smooth shift and almost zero power loss. The truck now wants to stay in each gearing longer as it wrings out as much power as it can before shifting to the next gear.
I live at 7200 ft. above sea level. I am still disappointed that I cannot get these tires to “chirp” as other people have mentioned here on the forum that have larger sized tires. I realize that isn’t indicative of anything to do with my vehicle. It is simply losing about 20% of my factory hp without anything substantial installed to make up that lost difference. I am sure that if I travel to a lower elevation, things would change.
I have not ran a tune with 91 or 93 octane. I thought my local gas stations only carried 85, 87 and 89 so I still need to back in touch with Sean and get a tune for the 93. With the increased cost at the pump, I may not run 93 very often, but I would like to see what it could do.
Now for the numbers.
Highway – As of right now, the best it is doing is 12.2. I haven’t ran it very far to see if this number will increase, but I am sure it will.
City – As of right now, if I can keep my foot out of it, it is a solid 11.6 and it will flirt with higher numbers until I get stuck idling at lights or on very cold mornings.
When I put my foot into the gas and then try to ease off, the numbers are quick to recover, thus leading me to believe I have not yet seen the maximum improvement for the mpg’s.
Small improvements over factory, but this is an 87 tune and Sean claims the real improvements come with the 93 tuning.
A few notes about the behavior of the truck since installing the tuner:
MDS functionality – I asked Sean to create two tunes, mild and aggressive. With the aggressive tune the MDS is set to off. The dash light still comes on when cruise control is set, but there is no change in the exhaust note. Sean claims it is turned off, so I would assume it is really turned off.
Speedometer – Tire size can be adjusted and thus, speed is corrected for your tire size. Just measure the tire before plugging in your numbers. I have 35” BFG’s, but they measure at 33.5”. Go figure. The tuner will show saving the tire size as a “failure”. But when you go back in to try again, your previous entry was saved. Again, go figure.
Traction Control – Since I haven’t “chirped” my tires, I don’t know if this is turned off. That is an option with Diablo. I get the same “failure” notification when attempting to adjust this setting, but you cannot tell if it is truly turned off when you go back in to check the settings. I may try tweaking the tune a bit to see if I can get the tires to break loose.
Installation – I couldn’t find any videos online for the 6.4, but a 5.7 install shows the ECU mounted to the firewall. Ours is located near the front grill making installation a snap. If you can operate your computer and download music to an IPod like device, you won’t have any troubles. One note, the instruction from Sean appear to be written for the push button ignition. Disregard the push button and use common sense with the key position and it will work just fine.
DDM tuning lights – Before the install, I was getting random headlight out error messages on my EVIC. Also, my passenger light would occasionally not turn on. I turned the headlight control from “auto” to “manual”. This help a bit, but it still didn’t solve my problem. Now with a new ECU, I have yet to experience any of this behavior from my headlights. Problem solved? Time will tell.
Overall, I am happy with my purchase. I wish I could have got it on sale or saved a few bucks somehow. With the additional purchase of an ECU it makes this purchase a bit more complicated. I figure I have an emergency back-up ECU in case this one goes belly up. This tuner seems to have breathed life into my truck that was lacking with factory settings. When passing slower traffic, there is more power available and it is pretty cool to have this beast of a truck blow the doors off smaller cars!
If you have any questions, please ask away. I’m sorry I could not put this on a dyno to get true numbers. That would be the ultimate test. But, when looking at posted results from other owners of Ram trucks (5.7) they have experienced significant improvements over factory with this tuner set-up.
2015 Power Wagon in Granite Metallic w/Rambox
Bak Flip G2, Westin Pro Traxx 4, twin JL Audio 10"subs powered by JL RD500x1, DDM Tuning HID low/LED high headlights, 35" BFG's, DeeZee tailgate assist, custom Magnaflow true dual exhaust, AEM Dryflow Airfilter, Diablo Intune2 w/Hemifever tuning
more to come...