E85 tune

milehighsubie303

New member
Have a couple questions, I have an e85 tune on my 2012 sti(open source) I keep getting code P0171 I can't get rid of it! Any suggestion? Anything I need to change? Thanks!
 

IGOTASTi

System Operator
Staff member
[MENTION=4577]TK-421[/MENTION] ;)
 

TK-421

New member
P0171 if I recall correctly is "System Too Lean Bank 1"

Have you check all your vacuum lines? And all your connections, have you removed your Intercooler or intake manifold at all?
 

TK-421

New member
Kinda need a little but more info, also do you have a tactrix cable? Is there anyway you can send me a datalog that I can look at?
 

milehighsubie303

New member
Kinda need a little but more info, also do you have a tactrix cable? Is there anyway you can send me a datalog that I can look at?

Ok so I have not removed intercooler I've checked for any leaks and don't have any I also replaced my O2 sensor the other day. I do not have a tactrix cable yet. Yea I'm not sure what keeps triggering that code
 

TK-421

New member
It could be a number of things, everything from mechanical, to electrical to the tune. What size of injector are you running? And can you give me a mod list?
 

Spamby

Meat Product Toy
Have a couple questions, I have an e85 tune on my 2012 sti(open source) I keep getting code P0171 I can't get rid of it! Any suggestion? Anything I need to change? Thanks!

This happened to me a while back and still does on occasion when fuel blends change with the seasons.
Since E70 was only available at the time, and since has changed to seasonal blends, when spring/summer blend happens I get the P0171 code. I then have to blend the higher Ethanol content fuel with gasoline.
What fuel are you tuned on, what blend ethanol?
I agree that logs need to happen to get a better understanding of what's going on.
 

milehighsubie303

New member
It could be a number of things, everything from mechanical, to electrical to the tune. What size of injector are you running? And can you give me a mod list?

Well mods are: 1000cc injectors from injectors dynamics, DW fuel pump, invidia catted DP, Grimm speed boost controller, Perrin CAI. That's all the mods sorry I couldn't have any datalogs for you guys :/ I'm not sure the blend of the fuel the pump I go to says at least 70% ethanol
 

TK-421

New member
Alright well if you can get me a datalog I'd be able to help you further, but right now other than checking for leaks in the vac lines, I'm just poking around in the dark.
 

Spamby

Meat Product Toy
Well mods are: 1000cc injectors from injectors dynamics, DW fuel pump, invidia catted DP, Grimm speed boost controller, Perrin CAI. That's all the mods sorry I couldn't have any datalogs for you guys :/ I'm not sure the blend of the fuel the pump I go to says at least 70% ethanol

Almost reads like my mid list.
Where are you located? I assume Colorado by your forum name? If that's the case, you should be receiving 3 blends of ethanol at various times of year. Spring/fall, summer and winter blends. Winter being around 70%, spring/fall at around 75-80 and summer at 80-85%. The pump just states that there is a minimum requirement at any time of year but it's not a guarantee.
What happens is if your tuned at a specific time of year, say winter or spring, your mapping and fueling is custom to that fuel blend of a lower ethanol content. If that content changes to a higher percentage, your ECU gets scared because your AF sensors are picking up an anomaly that your exhaust gasses see too much oxygen in the burnt fuel. This will cause the ECU to call for more fuel. At a certain percentage it will trip a lean code like p0171. The ECU is trying to keep things happy until it can't anymore and calls for help.
I'm not a tuner so I hope I didn't fark that up but that's my take on it.
Ideally you would want a tune for each blend of fuel. I've heard some recommend tuning on summer blends and just run a bit rich for the other seasons.
Another reason could be that the fuel you've bought is stale or has phase separated, causing the gas and alcohol to separate. Since ethanol is a lower volume seller, usually, this can and does occur.
Ethanol also has a knack for attracting water. If your climate has shifted wildly in temps or humidity levels, water can be found in the fuel system. A catch can also be installed from the heads and crankcase breathers to catch any moisture, or oil, so it's not recirculated into the combustion chambers.
Purchasing a simple ethanol test kit can be beneficial if you plan on using ethanol. They're about 20 bucks from places like quick fuel.

Not saying this is your issue but it's some food for thought. I literally tore my hair out, some years back, searching for phantom boost/vacuum leaks and the whole shebang when all along it was a fuel issue.

When was the car tuned on ethanol? What time of year?
 

TK-421

New member
Almost reads like my mid list.
Where are you located? I assume Colorado by your forum name? If that's the case, you should be receiving 3 blends of ethanol at various times of year. Spring/fall, summer and winter blends. Winter being around 70%, spring/fall at around 75-80 and summer at 80-85%. The pump just states that there is a minimum requirement at any time of year but it's not a guarantee.
What happens is if your tuned at a specific time of year, say winter or spring, your mapping and fueling is custom to that fuel blend of a lower ethanol content. If that content changes to a higher percentage, your ECU gets scared because your AF sensors are picking up an anomaly that your exhaust gasses see too much oxygen in the burnt fuel. This will cause the ECU to call for more fuel. At a certain percentage it will trip a lean code like p0171. The ECU is trying to keep things happy until it can't anymore and calls for help.
I'm not a tuner so I hope I didn't fark that up but that's my take on it.
Ideally you would want a tune for each blend of fuel. I've heard some recommend tuning on summer blends and just run a bit rich for the other seasons.
Another reason could be that the fuel you've bought is stale or has phase separated, causing the gas and alcohol to separate. Since ethanol is a lower volume seller, usually, this can and does occur.
Ethanol also has a knack for attracting water. If your climate has shifted wildly in temps or humidity levels, water can be found in the fuel system. A catch can also be installed from the heads and crankcase breathers to catch any moisture, or oil, so it's not recirculated into the combustion chambers.
Purchasing a simple ethanol test kit can be beneficial if you plan on using ethanol. They're about 20 bucks from places like quick fuel.

Not saying this is your issue but it's some food for thought. I literally tore my hair out, some years back, searching for phantom boost/vacuum leaks and the whole shebang when all along it was a fuel issue.

When was the car tuned on ethanol? What time of year?


For not being a tuner that's a spot on response that I would give, nice job buddy
 

Spamby

Meat Product Toy
For not being a tuner that's a spot on response that I would give, nice job buddy

Thanks bro. Old school carb and some basic obd1 type guy. Did a lot of engine building for old gas burners and mostly off-road vehicles. It's not completely alien to me and I can spout some basic knowledge.
Subaru is my first import tuner project. I'm learning the tuning for more modern things in my spare time... very spare time. Lol
 

milehighsubie303

New member
Almost reads like my mid list.
Where are you located? I assume Colorado by your forum name? If that's the case, you should be receiving 3 blends of ethanol at various times of year. Spring/fall, summer and winter blends. Winter being around 70%, spring/fall at around 75-80 and summer at 80-85%. The pump just states that there is a minimum requirement at any time of year but it's not a guarantee.
What happens is if your tuned at a specific time of year, say winter or spring, your mapping and fueling is custom to that fuel blend of a lower ethanol content. If that content changes to a higher percentage, your ECU gets scared because your AF sensors are picking up an anomaly that your exhaust gasses see too much oxygen in the burnt fuel. This will cause the ECU to call for more fuel. At a certain percentage it will trip a lean code like p0171. The ECU is trying to keep things happy until it can't anymore and calls for help.
I'm not a tuner so I hope I didn't fark that up but that's my take on it.
Ideally you would want a tune for each blend of fuel. I've heard some recommend tuning on summer blends and just run a bit rich for the other seasons.
Another reason could be that the fuel you've bought is stale or has phase separated, causing the gas and alcohol to separate. Since ethanol is a lower volume seller, usually, this can and does occur.
Ethanol also has a knack for attracting water. If your climate has shifted wildly in temps or humidity levels, water can be found in the fuel system. A catch can also be installed from the heads and crankcase breathers to catch any moisture, or oil, so it's not recirculated into the combustion chambers.
Purchasing a simple ethanol test kit can be beneficial if you plan on using ethanol. They're about 20 bucks from places like quick fuel.

Not saying this is your issue but it's some food for thought. I literally tore my hair out, some years back, searching for phantom boost/vacuum leaks and the whole shebang when all along it was a fuel issue.

When was the car tuned on ethanol? What time of year?

Thanks so much for the info. Well the car was tuned like in August and it was running fine. Then it had hesitation after third gear on high Rmps so had the fuel pump checked and the fuel regulator plus I added on step colder spark plugs then the problem was gone and it ran great. Around September I started running rich but the code(P0171) said lean so i went to get it re tuned and the code hasn't gone since, like I reset the ecu and sometimes it takes couple days and sometimes that same day it comes back.
 
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