rom tuning for improved gas milage - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

ganz954 · 11-23-2014, 04:46 PM

My goal is to create a rom that will give 10%-15% mileage increase.
Im not looking for performance here I just want to see if it is possible to achieve that. Dont care if the car is slow as a Prius.

Anyone have a clue how to achieve better gas mileage?
What tables should I start looking into?

Kodename47 · 11-23-2014, 05:17 PM

What tuning method, ECUtek or RomRaider?

I guess you could change the O2 sensor scale to read richer and therefore make closed loop operation be leaner. Having not looked into mileage tuning I wouldn't know how to adjust the timing although from memory you'd advance the timing a little.

Shiv@Openflash · 11-23-2014, 05:45 PM

Don't expect any big gains for improving fuel economy without hurting performance. The factory a pretty good job in this respect. The problem with leaning the AFR target at cruise is that you will also see a loss in engine torque which will require more throttle which will then meter more fuel and you are back to square one. You can problem get some minor gains by leaning AFR slightly and then adding a small amount of advance (2-3 deg) at cruise conditions. The factory couldn't get away with these changes due to emission constraints (primarily NOx emissions concerns). But the effects on mpg would be small and take some very controlled testing to quantify. Probably too controlled to street driving.

ganz954 · 11-23-2014, 08:18 PM

Romraider is my tuning method.
I have a stock car.
Ill try both of your suggestions and go from there.

shif7i7down · 11-24-2014, 01:07 AM

You 'll Have better luck with a 3.7final drive swap if you want that 10~15% mpg increase

steve99 · 11-24-2014, 03:53 AM

I got slightly better milage after installing OFH catless header suspect due better low end torque, but you have to drive very sedatly to achieve good economy in city.

ganz954 · 11-24-2014, 11:57 AM

@shif7i7down, I was going to swap out to a 3.7 final drive in a couple of years from now once I had a turbo installed. It seems like a good option to do it now and don't worry about the tune and just flash OFT rom files.

fantah · 11-24-2014, 02:22 PM

I got better mileage with the OFT Stage 1 tune 29.2 (without tune) 29.6 (With tune).

Poodles · 11-24-2014, 02:31 PM

Could possibly play with the drive by wire setup so it's not possible to full throttle.

Electronic equivalent of putting a block under the gas pedal.

Koa · 11-24-2014, 04:46 PM

Quote:

Originally Posted by ganz954

My goal is to create a rom that will give 10%-15% mileage increase.
Im not looking for performance here I just want to see if it is possible to achieve that. Dont care if the car is slow as a Prius.

Anyone have a clue how to achieve better gas mileage?
What tables should I start looking into?

hate to be 'that guy' to question the OP or suggest something contrary to what you're asking, BUUUT

is that ~2-3mpg increase really worth cutting the nuts off this car? One doesn't die with their money. Memories and experiences are all we really got at the end of the day.. just some food for thought.

I feel your pain though man. I drive 130 miles a day. Everett to Kent, WA.

Dadhawk · 11-25-2014, 09:40 AM

Over 51,000+ miles I have averaged 32.65MPG, as documented in my owner's journal thread. An increase of 10 to 15% would mean an increase in mileage of 3.2 to 4.8MPG.

Given the current focus on fuel economy requirements, I just don't see any way that Toyota/Subaru would have left that on the table if a simple ROM change would have upped it, even if it meant sacrificing performance a bit particularly given that straight-line, top speed performance was not their focus with the 86 platform.

wparsons · 11-25-2014, 11:17 AM

You'll get far better gains by changing your driving patterns than by re-tuning for economy.

s2d4 · 11-25-2014, 02:04 PM

Choke your intake so it can't flow enough air for 100hp. Redo MAF scale, retard some cam timing, done.

cdrazic93 · 11-25-2014, 03:04 PM

Quote:

Originally Posted by s2d4

Choke your intake so it can't flow enough air for 100hp. Redo MAF scale, retard some cam timing, done.

Step 3:???
step 4: drive slower than a prius

11-23-2014, 05:17 PM	#2
Kodename47 Senior Member Join Date: Oct 2012 Drives: UK GT86 Location: UK Posts: 3,040 Thanks: 185 Thanked 1,632 Times in 1,113 Posts Mentioned: 156 Post(s) Tagged: 1 Thread(s)	What tuning method, ECUtek or RomRaider? I guess you could change the O2 sensor scale to read richer and therefore make closed loop operation be leaner. Having not looked into mileage tuning I wouldn't know how to adjust the timing although from memory you'd advance the timing a little. __________________ .: Stealth 86 :. Abbey Motorsport/K47 Tuned Sprintex 210 Supercharger Kodename 47 DJ: Soundcloud / Instagram / Facebook

11-24-2014, 01:07 AM	#5
shif7i7down Erected Member Join Date: Mar 2014 Drives: frs Location: Wisconsin Posts: 391 Thanks: 69 Thanked 185 Times in 100 Posts Mentioned: 10 Post(s) Tagged: 0 Thread(s)	You 'll Have better luck with a 3.7final drive swap if you want that 10~15% mpg increase __________________ https://www.facebook.com/profile.php?=87912848

11-25-2014, 09:40 AM	#11
Dadhawk Senior Member Join Date: Feb 2012 Drives: '13 FR-S (#3 of 1st 86) Location: Powder Springs, GA Posts: 20,081 Thanks: 39,599 Thanked 25,401 Times in 11,581 Posts Mentioned: 187 Post(s) Tagged: 4 Thread(s)	Over 51,000+ miles I have averaged 32.65MPG, as documented in my owner's journal thread. An increase of 10 to 15% would mean an increase in mileage of 3.2 to 4.8MPG. Given the current focus on fuel economy requirements, I just don't see any way that Toyota/Subaru would have left that on the table if a simple ROM change would have upped it, even if it meant sacrificing performance a bit particularly given that straight-line, top speed performance was not their focus with the 86 platform. __________________ Olivia 05/03/2012 - 01/06/2024. 231,146 glorious miles. Visit my Owner's Journal where I wax philosophic on all things FR-S Post your 86 or see others in front of a(n) (in)famous landmark. What fits in your 86? Show us the "Junk In Your Trunk".

11-25-2014, 02:04 PM	#13
s2d4 Senior Member Join Date: Mar 2013 Drives: R32 GTR, AW11 MR2 SC, GTS86 R Location: OZ Posts: 2,615 Thanks: 603 Thanked 1,224 Times in 708 Posts Mentioned: 35 Post(s) Tagged: 0 Thread(s)	Choke your intake so it can't flow enough air for 100hp. Redo MAF scale, retard some cam timing, done. __________________

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11-23-2014, 05:45 PM	#3
Shiv@Openflash Senior Member Join Date: Sep 2013 Drives: 2013 FRS Location: SF, CA Posts: 2,629 Thanks: 1,055 Thanked 5,469 Times in 1,494 Posts Mentioned: 605 Post(s) Tagged: 9 Thread(s)	Don't expect any big gains for improving fuel economy without hurting performance. The factory a pretty good job in this respect. The problem with leaning the AFR target at cruise is that you will also see a loss in engine torque which will require more throttle which will then meter more fuel and you are back to square one. You can problem get some minor gains by leaning AFR slightly and then adding a small amount of advance (2-3 deg) at cruise conditions. The factory couldn't get away with these changes due to emission constraints (primarily NOx emissions concerns). But the effects on mpg would be small and take some very controlled testing to quantify. Probably too controlled to street driving.

11-24-2014, 03:53 AM	#6
steve99 Banned Join Date: Dec 2013 Drives: FT86 Location: Australia Posts: 7,996 Thanks: 1,035 Thanked 4,992 Times in 2,983 Posts Mentioned: 598 Post(s) Tagged: 2 Thread(s)	I got slightly better milage after installing OFH catless header suspect due better low end torque, but you have to drive very sedatly to achieve good economy in city.

11-24-2014, 02:31 PM	#9
Poodles Senior Member Join Date: Oct 2013 Drives: 2015 Series.Blue Location: Fort Worth, TX Posts: 1,781 Thanks: 88 Thanked 781 Times in 481 Posts Mentioned: 16 Post(s) Tagged: 0 Thread(s)	Could possibly play with the drive by wire setup so it's not possible to full throttle. Electronic equivalent of putting a block under the gas pedal.

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