how to disable flex fuel?

[Fless]

And if the Tech 2 owner is set up with TIS2000, the programming itself is free for the NBS. I did this with mine. If TIS2Web (online) is used then there is a fee to download the calibrations. Obviously there may be labor/time charges for whomever is doing the programming. For $375 you could have a Tech 2 of your own.

 

[slowride]

Well I found a guy locally who has an HP Tuners setup. Says he can disable/delete the flex fuel deal for like $200. I was reading some other posts about resetting the air/fuel mix to something like 14.1 for running on pump gas with up to 10% ethanol. May try to get him to set that as well unless Im wrong there. I would have tried recalibrating the computer relating to alcohol content setting just to try that if I could have gotten it done at a lower cost, however my real goal would be to just get rid of the whole flex fuel programming and the headache Ive had from it over the past year. Im about at the point of wanting to sell the truck and be done with it.

 

[Fless]

After you do the FF delete, and sell it, be sure to let the new owner know what's been changed.

 

[slowride]

This has been the most frustrating vehicle Ive dealt with, other than some odd stuff Ive had that you couldnt find parts for lol. And I really appreciate the information people have taken time to post. I really dont want to get rid of it, as clean as it is and the low miles it would be hard to replace from what I see for sale. I could have just reset the alcohol percent with the Tech II and sold it to somebody but Im not that kind of guy. Unless I find some other info, I guess Im gonna shell out the $200 and hopefully that will work.

 

[Scottydoggs]

200 aint to bad really, it costs $100 to unlock the file, be nice if he actually tuned the truck some too. i mean a 100 bucks for like 4 mouse clicks seems steep, trans tune would be nice. as thats most of what you feel when your tuning a stock car or truck.

 

[slowride]

As an update, I got the flex fuel turned off last week with HP Tuners. Ive had time to drive around a bit and do a couple fill ups. So far the truck runs much better and no more check engine light on. Checking my scan tool after each fill up, the alcohol percentage has stayed at 0. I had the guy set the alcohol percent at 5% on the fuel screen when he was running the program but as I said its showing 0%. Also set the fuel/air mix at 12.125 under column 0.0 in the stoich AFR tab but my truck is showing 14.67. Dont know if those values were supposed to get "locked in" or what, but that is what I had read to set them at in some other posts on related topic. My fuel trims went from negatives to positives and thats something Im looking into and will probably put in another post. Again, thanks for all the replies offering help

 

[Scottydoggs]

how far pos? 5 to 8 is pretty normal. if that stoich AFR you changed was in the flex fuel tab im sure its ok. but once you set it to disable nothing about it should matter, its like a on off switch. scan your commanded afr should be 14.6 idle and cruise, then the afr drops when you go wot and enter whats called pe mode, power enrichment, it adds more fuel. commanded should be some where in the 12's wot id think. only way to really know is to run a wide band. then you know exactly whats coming out the tail pipe.

 

[slowride]

OK heres some pics. If you look at the vehicle speed on the screen, one is at idle with the - numbers, one is normal cruising at about 55mph/1500 rpms, and one is accelerating from 55mph not wot but maybe 50% pedal. They are average representations from multiple drives which only varied one or two numbers, but most of the time driving normally the long term trims both banks are trying to stay right about +6

 

[Scottydoggs]

13's are a bit lean. maybe have that afr setting put back to the way it was. see if it makes a difference.

 

[swathdiver]

thanks for the replies. This model has the "virtual' sensor that needs to be disabled. If I knew what to unplug it would be gone. Ive had this thing reset so many times now that the guy at the shop just hands me his tech tool when I pull up. I went by the local Chevy dealer to ask about any ecm update to fix the issue and that went nowhere

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 forever.