how to disable flex fuel?

[slowride]

Are you saying my rig has an actual sensor? I swear I read in some posts that this year model has a "virtual" sensor that works off fuel algorithms or something. If it is supposed to have an actual sensor, do you know where its located? Thanks

 

[Fless]

On the left frame rail. Crawl under and find the crossmember forward of the fuel tank. Juest forward of the crossmember will/should be a fuel filter, and the fuel composition sensor is close by if you have one. If I can find a pic of it I'll post it up.

EDIT: this guy shows where it might be on yours, if you have one:

 

[Mudsport96]

As Randy mentioned earlier, this model has the sensor and they are about a hundred bucks for an aftermarket one. We're referring to a GMT800 Tahoe with the L59, VIN "Z" Flex Fuel motor. Nothing man makes lasts

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.

So if his is indeed a 2006 he does not have the ethanol content sensor to go bad and cause enrichment issues. However, a bad intake gasket or vacuum leak can cause a false reading that is interpreted as higher ethanol content and the system adjusts accordingly. This is why i haven't gotten a tune for my 06.

 

[mikeyss]

Tired of having issues with my 06 Tahoe 5.3 FFV, fuel alcohol percent staying at 60 for the past couple tanks and its running like crap. Can the Chevy dealer or someone go in and disable the flex fuel? Thanks

Just put 87 octane in it and FFV is disabled.

 

[swathdiver]

Are you saying my rig has an actual sensor? I swear I read in some posts that this year model has a "virtual" sensor that works off fuel algorithms or something. If it is supposed to have an actual sensor, do you know where its located? Thanks

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.

So if his is indeed a 2006 he does not have the ethanol content sensor to go bad and cause enrichment issues. However, a bad intake gasket or vacuum leak can cause a false reading that is interpreted as higher ethanol content and the system adjusts accordingly. This is why i haven't gotten a tune for my 06.

When I saw this post, I went to GMPartsDirect and ACDelco's website and did indeed come across the actual sensor. GM went to a virtual sensor for the GMT900s which began production in December 0f 2005. So there was an overlap with both models being produced a the same time.

Randy posted a picture of it earlier.

Mudsport96 ought to check under his Tahoe too since he has an L59 as well.

 

[Mudsport96]

Mudsport96 ought to check under his Tahoe too since he has an L59 as well

I have, that is why i posted up the gm info. As mine does not have the sensor and has the virtual operating system. Guess i should not assume that it was applied across the board to all 06 vehicles.

 

[swathdiver]

I have, that is why i posted up the gm info. As mine does not have the sensor and has the virtual operating system. Guess i should not assume that it was applied across the board to all 06 vehicles.

Well, I'd be more inclined to believe you two guys than GM or ACDelco.

 

[slowride]

I will take a look to just check, Id like to know for sure. I dont know sometimes regarding what is "supposed" to be on the vehicle. I know when I bought it I went and got new belts and filters to put on and even though there was a listing for a fuel filter, this one doesnt have one like my 04 did.

 

[Mudsport96]

Well, I'd be more inclined to believe you two guys than GM or ACDelco.

From 04 to 06 i worked at a chevy/hummer dealer... sometimes there is no rhyme or reason to GMs application of certain parts.