07' Flex Fuel Compatibility

[hmmhunter]

Hello,

I recently bought a 2007 Yukon XL Denali (6.2L Vortec) and am having some problems with it. It has the FlexFuel badge on the back, and so I've been using E85 but every time I do, it throws codes (lean fuel bank 1 and 2) and has a hard time starting.
I figured it just wasn't registering the change in fuel type, so I've replaced the oxygen sensors and have a new ECM on the way. I started looking around online and noticed that my car does not have a yellow gas cap, and then also read that this particular engine didn't take flex fuel until 2011.

Any idea if it is possible that my car actually doesn't take flex fuel even though it has the badge on the back? If it does take it, any tips on what to do if it keeps throwing codes while using E85?

Thanks,
Hunter

 

[avalonandl]

No E85 in that engine.

 

[Fless]

Makes one wonder if the liftgate was replaced at some point. You can look inside the fueling door for a small sticker that has icons representing E85 compatibility, or not.

 

[hmmhunter]

No E85 in that engine.

I agree, I just don’t understand why it has the flex fuel badge on the tailgate if that’s the case.

Has anyone tried swapping in the L9H? Do they fit the same or would it cause problems?

 

[swathdiver]

Hello,

I recently bought a 2007 Yukon XL Denali (6.2L Vortec) and am having some problems with it. It has the FlexFuel badge on the back, and so I've been using E85 but every time I do, it throws codes (lean fuel bank 1 and 2) and has a hard time starting.
I figured it just wasn't registering the change in fuel type, so I've replaced the oxygen sensors and have a new ECM on the way. I started looking around online and noticed that my car does not have a yellow gas cap, and then also read that this particular engine didn't take flex fuel until 2011.

Any idea if it is possible that my car actually doesn't take flex fuel even though it has the badge on the back? If it does take it, any tips on what to do if it keeps throwing codes while using E85?

Thanks,
Hunter

The L92 is not a FlexFuel motor as you are learning. To make it so, get the injectors/fuel rail and the fuel pump module assembly from an L9H. Programming will be required of course but then you'll basically have an L9H 6.2.

L9H was introduced in 2009 and continued production until 2013 in the pickup trucks.

 

[hmmhunter]

The L92 is not a FlexFuel motor as you are learning. To make it so, get the injectors/fuel rail and the fuel pump module assembly from an L9H. Programming will be required of course but then you'll basically have an L9H 6.2.

L9H was introduced in 2009 and continued production until 2013 in the pickup trucks.

Thanks for the help! If I do that, do I need to be concerned about the fuel line as well or are they ok for E85?

 

[swathdiver]

Thanks for the help! If I do that, do I need to be concerned about the fuel line as well or are they ok for E85?

They are the same, so no need to change them.

 

[hmmhunter]

They are the same, so no need to change them.

Good to know, thanks!

I was already looking to replace my motor in the next few months, if I find an L9H would it fit exactly the same or am I better off getting an L92 and just modifying it to take flex fuel?

 

[swathdiver]

Good to know, thanks!

I was already looking to replace my motor in the next few months, if I find an L9H would it fit exactly the same or am I better off getting an L92 and just modifying it to take flex fuel?

Since you have a Yukon XL, I don't think your engine is one of the earliest ones with AFM components but turned off in the tune. The valley plate under the intake manifold would be lumpy and not smooth if it has it. Those engines were made before April of 2006 or so. If it does, the camshaft while having the same numbers as the L9H is made for AFM and would have to be changed if you were wanting to install a performance camshaft.

The only difference between a regular L92 and the L9H is the tune and larger injectors/fuel pump for the FlexFuel capability.

These LS engines are all the same dimensionally. You could drop a 4.8 or 5.3 into the same spot with no modifications except wiring and the tune in some cases.

 

[hmmhunter]

Since you have a Yukon XL, I don't think your engine is one of the earliest ones with AFM components but turned off in the tune. The valley plate under the intake manifold would be lumpy and not smooth if it has it. Those engines were made before April of 2006 or so. If it does, the camshaft while having the same numbers as the L9H is made for AFM and would have to be changed if you were wanting to install a performance camshaft.

The only difference between a regular L92 and the L9H is the tune and larger injectors/fuel pump for the FlexFuel capability.

These LS engines are all the same dimensionally. You could drop a 4.8 or 5.3 into the same spot with no modifications except wiring and the tune in some cases.

Thanks for the info!
As far as tuning goes, could I just buy a new ECM that’s programmed for the 2009 with an L9H and plug that in or would it be a little more complicated?