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02-27-2021, 08:49 AM | #1 |
Scooby Specialist
Member#: 100587
Join Date: Nov 2005
Chapter/Region:
South East
Location: Odessa
Vehicle:2020 STi Ltd Red |
High Negative AF 1 Numbers ~-17 20 STI E85
Hello everyone,
I have been having an issue with high negative AF (~ -17) numbers during idle/low rpm driving for quite some time now and it's really been bothering me. I was hoping to get some advice on what to check/look for from the forum. Car 2020 Sti ~6k Miles Mod Info: AEM 340 Fuel Pump Cobb 1050 Injectors Cobb Fuel Lines Aeromotive A1000 IAG V3 Top Feed IAG Top Feed TGV PRL EGR Delete Kit IAG 3mm Phenolic Spacers Perrin Red 2.4in Turbo Inlet Grimmspeed 3-Port EBC COBB Flex Fuel Package Grimmspeed Turbo Heat Shield V2 Cobb LF By-Pass Valve GrimmSpeed Ltd Downpipe (w/ Cat, Black Ceramic Perrin CAI Perrin FMIC NGK IRIDIUM ONE STEP COLDER 2309 SPARK PLUG I reached out to the tuner and the shop that did most of the installs and basically got some finger-pointing and then was told it's not a big deal.... Observations: Seems to be a correlation between ethanol content and numbers (the more ethanol the less negative AF) Log Files on 93: https://drive.google.com/drive/folde...rU?usp=sharing Thank you so much in advance for any assistance
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02-27-2021, 12:10 PM | #2 |
Scooby Newbie
Member#: 518830
Join Date: Sep 2020
Chapter/Region:
RMIC
Location: Colorado
Vehicle:2009 WRX dark grey metallic |
Maybe the maf wasn’t scaled at idle low speed?
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02-28-2021, 08:34 AM | #3 |
Scooby Specialist
Member#: 100587
Join Date: Nov 2005
Chapter/Region:
South East
Location: Odessa
Vehicle:2020 STi Ltd Red |
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02-28-2021, 08:44 AM | #4 |
Scooby Specialist
Member#: 508105
Join Date: Nov 2019
Chapter/Region:
NWIC
Location: Greater Seattle Area
Vehicle:Link G4X flex tuned 02' EJ205 20G 6MT wagon |
Run a couple more tanks through it to see if it clears up.
If they tuned the car, and you are having issues with their tune, they should resolve them for you. And if you haven't changed anything mechanically since they tuned it, they should honestly do it for free since you paid for a proper tune. Harass the shop that tuned the car and ask them if it is within a range they are comfortable with and if it is not, ask them to correct it. They will likely ask you for longer data logs to get a better sense of what is happening, those logs are fairly small. If they refuse to touch up a tune without a good explanation of why the car is currently tuned safely, even after you've documented issues through multiple tanks of fuel, it's time to find a better tuner. Good luck. |
02-28-2021, 04:37 PM | #5 | |
Scooby Specialist
Member#: 100587
Join Date: Nov 2005
Chapter/Region:
South East
Location: Odessa
Vehicle:2020 STi Ltd Red |
Quote:
I am looking for a new tuner in my area. |
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03-02-2021, 11:28 AM | #6 |
Scooby Guru
Member#: 108051
Join Date: Feb 2006
Chapter/Region:
AKIC
Location: Oneonta, NY
Vehicle:2005 WRX STi WRB |
A lot of people like to blame the tune or tuner. Id start blaming perhaps an aftermarket item you have on the car such as an electrical device. Causing EMI.. Like a radio ext ext. I'm having the same issue. Didnt do it previously on the same tune. So I'm kinda against saying it's the tune. I believe my issue lays in the wire harness. I've went over everything. Who knows maybe my camshaft or crankshaft has some type of magnification going on causing the issue with that.
Last edited by spoolinsti05; 03-02-2021 at 11:35 AM. |
03-02-2021, 12:26 PM | #7 |
Scooby Newbie
Member#: 400179
Join Date: Aug 2014
Vehicle:2009 wrx |
This part that you said is interesting: "Seems to be a correlation between ethanol content and numbers (the more ethanol the less negative AF)"
I wonder if the flex fuel aspect of your tune is working properly? By nature 93 is "richer" and e85 is "leaner", but the flex fuel sensor and tune are supposed to adjust for that. Seems odd to me that it isn't adjusting appropriately. |
03-02-2021, 04:26 PM | #8 | |
Scooby Guru
Member#: 108051
Join Date: Feb 2006
Chapter/Region:
AKIC
Location: Oneonta, NY
Vehicle:2005 WRX STi WRB |
Quote:
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03-02-2021, 05:39 PM | #9 |
Scooby Newbie
Member#: 400179
Join Date: Aug 2014
Vehicle:2009 wrx |
totally agree. but a working flex fuel system should adjust to any amount of ethanol and the fuel trims shouldn't swing as wildly.
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03-05-2021, 07:23 AM | #10 | |
Scooby Specialist
Member#: 100587
Join Date: Nov 2005
Chapter/Region:
South East
Location: Odessa
Vehicle:2020 STi Ltd Red |
Quote:
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