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01-05-2017, 01:35 AM | #1 |
Scooby Newbie
Member#: 423516
Join Date: Jun 2015
Chapter/Region:
NESIC
Location: RI
Vehicle:2015 WRX Premium Lightning Red |
Cobb OTS maps versus gas mileage
Looking for input: seems like ever since loading up the Cobb Stage 1, 93 octane map on the '15 WRX, gas mileage has gone down quite noticeably. I have NOT changed driving habits, pedal mashed, or even changed routes that much, but I've noticed at least a 2-3mpg reduction, getting about 250-275 miles on a full tank. Most folks say that changing the maps to an OTS one smooth out power caused no mileage dips at all, but I beg to differ. Anyone else have this issue? Getting avg 17mpg city isn't good.
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01-05-2017, 12:06 PM | #2 |
Medium Frank
Moderator Member#: 140114
Join Date: Feb 2007
Chapter/Region:
MAIC
Location: Common Sense, VA
Vehicle:2020 Subaru Outback |
Driving style + winter fuel blend + moar boost = less mpg.
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01-05-2017, 01:21 PM | #3 |
Scooby Specialist
Member#: 375462
Join Date: Dec 2013
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:2006 Impreza WRX STI WR Blue |
Being in a perpetual state of warm-up enrichment is never good. This 17 is bad? Try 12.
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01-05-2017, 04:13 PM | #4 |
Scooby Newbie
Member#: 456662
Join Date: Oct 2016
Location: Lakewood, Colorado
Vehicle:2016 WRX |
That is pretty terrible 17 in the city for these new WRXs, i was getting slightly better mpg on Cobbs tune (27 city, 35 hwy) over stock.
Just running the stock map I assume, no mods? It might just be driving style on this new tune combined with the terribleness of winter gas. Your AP is fully updated and the map is the most recent version, correct? |
01-05-2017, 10:12 PM | #5 |
Scooby Guru
Member#: 60324
Join Date: Apr 2004
Location: soon to be somewhere else
Vehicle:1998 RS |
consider it insurance. i don't know for sure about 2015, but i know in years past one of the major improvements in the cobb ots map over stock was the removal of the cl/ol fueling delay. this allows you to run into richer points of the map without hanging at 14.7 under boost. your engine and wallet will thank you in the long run.
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01-08-2017, 09:43 AM | #6 |
Scooby Newbie
Member#: 426741
Join Date: Jul 2015
Chapter/Region:
Tri-State
Vehicle:2012 Wrx sti Black |
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01-09-2017, 01:17 AM | #7 |
Scooby Specialist
Member#: 375462
Join Date: Dec 2013
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:2006 Impreza WRX STI WR Blue |
Yep - I've yet to do a full freeway tank test to see what I can get out of it since having it tuned.
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01-09-2017, 10:26 AM | #8 |
Scooby Newbie
Member#: 448544
Join Date: Jun 2016
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I can only tell for STI:
COBB Stage 2 vs Stage 2 ProTune = ~2mpg difference COBB Sage 3 vs Stage 3 ProTune = ~3mpg difference both in ProTune favor |
01-09-2017, 02:58 PM | #9 |
Scooby Specialist
Member#: 375462
Join Date: Dec 2013
Chapter/Region:
NWIC
Location: Portland, OR
Vehicle:2006 Impreza WRX STI WR Blue |
^ This assumes you keep an OEM-based ECU which is VERY good as closed loop fuel fueling reduction.
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01-10-2017, 01:53 AM | #10 | |
Scooby Newbie
Member#: 423516
Join Date: Jun 2015
Chapter/Region:
NESIC
Location: RI
Vehicle:2015 WRX Premium Lightning Red |
Quote:
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01-10-2017, 03:11 PM | #11 |
Scooby Newbie
Member#: 456662
Join Date: Oct 2016
Location: Lakewood, Colorado
Vehicle:2016 WRX |
Take a few logs, maybe there's a leak or something. Monitor your AF Learning 1, and your AF Sensor 1 Ratio. (AF - Air/Fuel)
AF Sensor Ratio 1 is going to be the readings from the front 02 sensor, which can be used as a wideband for these cars. You're wanting 14.7ish cruising, dropping to 11 or so under full boost WOT, and usually low 12s to 11s for mid boost situations. AF Learning is going to be your long term fuel trims, IE what it takes for your engine to keep the correct 14.7/1 AFR - negative values indicate fuel being removed and positive values indicate fuel being added. Normal variance on these DITs is between +/- 13% - according to my emails with Cobb, so if you frequently see high numbers past that while cruising it could indicate a leak. With that being said, I was frequently seeing my AF learning jump to -15 while sitting at idle on Cobb's map, but when I got E tuned my tuner said there is no evidence of any leaks - so keep that in mind. WOT your AF learning should be 0.00 - your car switches to open loop fueling so it's not longer using information from the 02 sensor - it's basically speed density at that point (ie each rpm gets assigned specific AFR values, rather than relying on sensor). My suggestion, take a 2-3 minute log - keep it under 2-4 lbs of boost - just light driving and take a look at your numbers (or post them here). Also, take a 3rd Gear, 2500-6500RPM pull at 100% accel and see what that looks like. If you're AF Sensor is not close to 11 - if it's really rich or lean that could indicate a leak or a restriction. |
01-11-2017, 09:40 AM | #12 |
Scooby Newbie
Member#: 461127
Join Date: Jan 2017
Location: Milwaukee, WI
Vehicle:2005 WRX Black |
Small drop
I noticed a small drop in gas mileage on the stage 1 tune but only cruising high speeds when boost was starting to build around 3500rpm
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01-16-2017, 04:25 PM | #13 |
Scooby Newbie
Member#: 423516
Join Date: Jun 2015
Chapter/Region:
NESIC
Location: RI
Vehicle:2015 WRX Premium Lightning Red |
Thanks for the suggestions Miggy. I'll see what I can log...
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05-29-2019, 06:30 PM | #14 |
Scooby Newbie
Member#: 501958
Join Date: May 2019
Vehicle:2019 WRX Ice Silver |
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