Flex os tuning without sensor

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Mudsport96

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Hello, I've been considering a tune on my 06 Tahoe L59 SUV and have kind of come to an impasse.
In researching flex vehicle issues I've found some people have issues tuning the later P59 with the virtual flex fuel OS, like suddenly going to full e85 scale on regular fuel and over advancing timing. My OS is 12605114 from what I can tell is one of the early 2006 software versions (12587811 > 12605114 > 12606807 > 12613246).

Do you prefer tuning flex vehicles with the sensor as it helps to know actual ethanol content or is the estimated content ok?
I have considered installing and wiring in the real sensor and getting an older OS installed, but thought advice from a knowledgeable source to be the best plan.


I need to do a few things before I do get a tune per your site. New O2 sensors as these are original, fix the broken manifold bolts so the exhaust tick goes away and get a correct afr reading. And possibly wire a fuel composition sensor if you think that's necessary.

Thanks for any help
 

BlackBearPerf

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Hello, I've been considering a tune on my 06 Tahoe L59 SUV and have kind of come to an impasse.
In researching flex vehicle issues I've found some people have issues tuning the later P59 with the virtual flex fuel OS, like suddenly going to full e85 scale on regular fuel and over advancing timing. My OS is 12605114 from what I can tell is one of the early 2006 software versions (12587811 > 12605114 > 12606807 > 12613246).

Do you prefer tuning flex vehicles with the sensor as it helps to know actual ethanol content or is the estimated content ok?
I have considered installing and wiring in the real sensor and getting an older OS installed, but thought advice from a knowledgeable source to be the best plan.


I need to do a few things before I do get a tune per your site. New O2 sensors as these are original, fix the broken manifold bolts so the exhaust tick goes away and get a correct afr reading. And possibly wire a fuel composition sensor if you think that's necessary.

Thanks for any help
We would be happy to help with a tune, the AutoCal V3 will allow us to see your vehicle data and provide the custom tunes via email. There is really not an E85 tune per se, if you are flex fuel capable you will be able to run it on either octane tune that we provide with our AutoCal, 89/87 and 91+, we see a little more power running E85 with the 91+ tune.

If your vehicle is not flex fuel capable the tuner will not alter the flex fuel tables until you add the sensor.

For turbo tuning, that's when we would require a wideband O2 sensor for tuning along with possibly more work/components on your end.
 
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Mudsport96

Mudsport96

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There is really not an E85 tune per se, if you are flex fuel capable you will be able to run it on either octane tune that we provide with our AutoCal, 89/87 and 91+, we see a little more power running E85 with the 91+ tune.

If your vehicle is not flex fuel capable the tuner will not alter the flex fuel tables until you add the sensor.
See that's the issue I'm having. My L59 does NOT have the sensor.
In 2006 GM got rid of the sensor.

For 2006 and 2007 models, E85 compatible GM vehicles marketed in North America no longer use an alcohol sensor to determine and adjust for the alcohol content of the fuel in the tank. Instead, the vehicle "learns" (calculates) the alcohol content of the fuel, (and subsequent mixture in the fuel tank), through a series of measured adjustments.

Adjustments

After the re-fueling event, the system registers the amount of fuel that was taken on-board, relative to the amount that was in the tank. Reading fuel trim and O2 sensor activity, the system determines the ethanol content of the fuel that was added. Based on that determination, it adjusts itself to the expected alcohol mix in the fuel tank and lets the fuel trim and O2 sensor activity fine tune the adjustments. The system must remain in closed loop in order for this adjustment to occur. Numerous short trips after switching from gasoline to E85, or vice versa, can result in driveability symptoms due to the inability of the system to adjust for fuel composition (by not attaining the parameters necessary to reach closed loop operation.

That's where I was asking if installing a sensor and reverting to a pre2006 OS is better. In which case I would have to do that swap and drive it before even getting the autocal so I can or out any mechanical issues after the install
 

BlackBearPerf

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See that's the issue I'm having. My L59 does NOT have the sensor.
In 2006 GM got rid of the sensor.

For 2006 and 2007 models, E85 compatible GM vehicles marketed in North America no longer use an alcohol sensor to determine and adjust for the alcohol content of the fuel in the tank. Instead, the vehicle "learns" (calculates) the alcohol content of the fuel, (and subsequent mixture in the fuel tank), through a series of measured adjustments.

Adjustments

After the re-fueling event, the system registers the amount of fuel that was taken on-board, relative to the amount that was in the tank. Reading fuel trim and O2 sensor activity, the system determines the ethanol content of the fuel that was added. Based on that determination, it adjusts itself to the expected alcohol mix in the fuel tank and lets the fuel trim and O2 sensor activity fine tune the adjustments. The system must remain in closed loop in order for this adjustment to occur. Numerous short trips after switching from gasoline to E85, or vice versa, can result in driveability symptoms due to the inability of the system to adjust for fuel composition (by not attaining the parameters necessary to reach closed loop operation.

That's where I was asking if installing a sensor and reverting to a pre2006 OS is better. In which case I would have to do that swap and drive it before even getting the autocal so I can or out any mechanical issues after the install
Gotcha, Justin, our tuner, would know all of this, he is available via email [email protected]
 

randeez

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i dont think you need to revert back to a different OS, afaik all of the GM OSs that have the virtual sensor can be modified in the tune to accept the physical sensor. you would need to identify the correct input pin for the ecu install and wire it to the composition sensor.

whether its needed or not is up for debate. in my experience the virtual sensor seems to ballpark the ethanol content within 10%, i would fill up the same (only) 5 places and would always be 60-65% with the virtual. with the physical sensor i've seen the same 5 places 65-88% E content over the course of a year and a half probably. this was going through 2 tanks a week of "E85" over that year and a half, never e30 or e50 or anything

now whether it is actually needed or not, the virtual sensor can easily tell between regular gas (e10) and e85...how precisely you want to know that value is up to you. the performance benefit between e60 and e80 out of the pump is pretty negligible. in other words, any extra timing youre adding for running ethanol i would never tune it so razor thin that at e80 youre good with 28* but it knocks on e60 (made up numbers of course)

on my 2012, not sure if the older P59 is the same but, the virtual sensor is only looking for change in ethanol content after it sees a change in fuel level and for a fairly narrow window (a few minutes). may have been in my head but it seemed that the more you got into it the higher the content would register, where as say i filled up and pulled out directly into stop and go traffic it would stay low
 
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Mudsport96

Mudsport96

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i dont think you need to revert back to a different OS, afaik all of the GM OSs that have the virtual sensor can be modified in the tune to accept the physical sensor. you would need to identify the correct input pin for the ecu install and wire it to the composition sensor.

whether its needed or not is up for debate. in my experience the virtual sensor seems to ballpark the ethanol content within 10%, i would fill up the same (only) 5 places and would always be 60-65% with the virtual. with the physical sensor i've seen the same 5 places 65-88% E content over the course of a year and a half probably. this was going through 2 tanks a week of "E85" over that year and a half, never e30 or e50 or anything

now whether it is actually needed or not, the virtual sensor can easily tell between regular gas (e10) and e85...how precisely you want to know that value is up to you. the performance benefit between e60 and e80 out of the pump is pretty negligible. in other words, any extra timing youre adding for running ethanol i would never tune it so razor thin that at e80 youre good with 28* but it knocks on e60 (made up numbers of course)

on my 2012, not sure if the older P59 is the same but, the virtual sensor is only looking for change in ethanol content after it sees a change in fuel level and for a fairly narrow window (a few minutes). may have been in my head but it seemed that the more you got into it the higher the content would register, where as say i filled up and pulled out directly into stop and go traffic it would stay low
Cool, thank you for the info. So far I havent had too much issue with the Tahoe and fuel. But sometimes the Mrs will fill it up and go right home and depending on where she gets fuel it could be e85 or regular 87 since she sees the cheapest price and puts it in the tank. And since the program needs a few miles to hit closed loop after a fill up to calculate the change, she never hits that so sometimes it has a stumble on the next drive then it irons itself out after a bit. So I was thinking of going to the sensor anyway to help alleviate some of that.
 

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