Has anyone observed actual fuel economy gains from chip tune? - PeachParts Mercedes-Benz Forum

shertex · #1 05-10-2015, 03:09 PM

I'm familiar with the various claims for and explanations of fuel economy gains when doing a chip tune. That was part of what motivated me to get my 98 E300 tuned (Stage 2 from Rocketchip) about a year ago. While the power improvements were real and measurable, I noticed absolutely no fuel economy gains.

I have no regrets about doing the tune...but a bit disappointed I'm still getting the same mpg. FYI it's 26.4 mpg over the course of 6500 miles, 72% highway driving.

Skid Row Joe · #2 05-10-2015, 03:18 PM

Yes. My Ford 7.3 liter PowerStrokeDiesel got an improvement of 1 to 2 mpg when programmed with a tuner and the removal of it's muffler.

Skid Row Joe · #3 05-10-2015, 06:03 PM

I had a cross - country run of 1,500 miles to record several fuel calculations, so, I can absolutely report a 10% to 20% increase in mpg for my truck.

I would suspect that doing away with the constrictive exhaust components would give any diesel ' s mpg return a kick Upward. 1 mpg is approximately a 10% increase in fuel economy on an HD truck. Quite significant!

What I don't have is data on these separately, because the detuning of the engine programming was coupled with a replacement muffler.

Skid Row Joe · #4 05-10-2015, 06:05 PM

Quote:

Originally Posted by shertex

I'm familiar with the various claims for and explanations of fuel economy gains when doing a chip tune. That was part of what motivated me to get my 98 E300 tuned (Stage 2 from Rocketchip) about a year ago. While the power improvements were real and measurable, I noticed absolutely no fuel economy gains.

I have no regrets about doing the tune...but a bit disappointed I'm still getting the same mpg. FYI it's 26.4 mpg over the course of 6500 miles, 72% highway driving.

Your exhaust system may be what's holding your mpg back. Is it legal to deconstruct your constrictive exhaust system in your State?

shertex · #5 05-10-2015, 10:35 PM

Not sure about exhaust regulations. The tuner indicated that Stage 2 was (a) the most I could do without hardware mods (e.g. exhaust) and (b) that it would yield a 3-4 mpg increase. That didn't happen.

mytmousemalibu · #6 05-11-2015, 12:03 AM

For what its worth, I gained 3-4 MPG after a bunch of supporting mods and tuning on my Duramax and the tune isn't really an MPG tune but more of a towing tune. I have a programmer/flasher called EFI Live which essentially makes the OEM engine electronics a standalone fully tuneable computer. I can adjust anything I want, engine & transmission plus it is a data logger and scan tool. Its a pretty sweet system. I deleted the large coil intake heater element (not needed here) and went in with my laptop and switched the circuit off in the ECM and turned off the fault code for it! I can even change the message in the inst. cluster when you start the vehicle from, "Fasten your seatbelt" to what ever I want it to say! I wish this type of system was available for more vehicles.

KarTek · #7 05-11-2015, 11:48 AM

I have never been able to understand how a chip tune on this engine would give a MPG increase. All the ECU can do is control the rack. Now, they might have a less aggressive fueling curve but that would defeat the purpose if you want snappier performance.

I have the identical experience with my PSD to Joe above. The injection on this engine is a different animal and the ECU has direct control over injection events and timing. The tuners can dial in more advance to boost economy.

I can literally sit in the truck with it idling, change fuel/timing maps and hear the sound of the engine change as the ECU adds timing on the economy setting.

On my car, I gained about 1-2 MPG after I switched pump elements and injector nozzles. My assumption is that the increased combustion efficiency is the "culprit" in this case.

oldsinner111 · #8 05-11-2015, 12:43 PM

Any chip that connect to your maf,or air temp sensor is simply a resistor.The only real thing for most mercedes,is mail you computer to be chipped,about $500.You can on gasoline engines advance timing be using 1.1k resistor between temp sensor to computer.Diesels nneed larger volume injectors,and a pump that will fill them,and if electronic,a updated program.

Skid Row Joe · #9 05-11-2015, 03:50 PM

Quote:

Originally Posted by shertex

Not sure about exhaust regulations. The tuner indicated that Stage 2 was (a) the most I could do without hardware mods (e.g. exhaust) and (b) that it would yield a 3-4 mpg increase. That didn't happen.

Pull your exhaust restrictions.

See KARTEK's post.

I'm betting your tuner doesn't want to get involved with pulling exhaust systems or regulations.

mytmousemalibu · #10 05-11-2015, 06:18 PM

I agree with the general thoughts on the E300D, there isn't much control over the engines fueling, its still a mechanical pumped IDI engine. On our tuned trucks for example, for one they are direct injection and the big ticket is there is vastly more variable control over the injection system with electronics.

I also agree, to gain more back, your going to have to tinker with more mechanicals of the car to see gains. Less exhaust restriction and better breathing will help make the most of what the chip has made available. Getting rid of the EGR and cleaning all of the gunk out of the intake and intake ports will help tremendously if they look anything like my 606 did. The buildup in most of my ports was about 50% plugged up at the valve, a few were worse than that.

shertex · #11 05-12-2015, 06:35 AM

Makes sense. But I'm plenty happy with the car as is, so no real inclination to modify any of the hardware. Definitely performs better than it did.

m1tch · #12 05-22-2015, 03:00 AM

On previous cars I have had remapped I have found that the actual map isn't what gives the increase in MPG but more about the ability to drive more efficiently - I have found with a remap the throttle response is sharpened up a bit and there is increased low down torque. This means that you don't need to put your foot down as much or as long to get the car to maintain a certain speed. Couple the remap with an air intake and better exhaust to further increase throttle response and you will see an improvement in MPG overall. Remapping on the CDI will yield better MPG increase owing to the fact that the fuel is injected more precisely. Initially its probably best to just give the car a really good service and change all of the fluids. I would definitely change the airfilter for a new one (even the paper ones are fine) and cleaning the MAF sensor would also be a good idea.

Although saying that, my daily drive (Renault Clio 1.5dci) is currently averaging around 83mpg, the only difference on that car is that I have removed the restrictive snorkel which feeds the airbox, everything else is stock (Manufacture claimed figures are only 67mpg!).