flex fuel tuning?

[2000_SS]

I'm in the process of building a '03 Chevy Blazer for a guy. i'm installing a 4.8 he purchased for it and now he wants to put a turbo on it now. it's a toy, not a daily.

He's thinking he wants to run it on E85. The problem there is that we only have one gas station in the area that sells E85. it's about a 20-25 minute drive one way for him. Also, as in most cases, the ethanol content ranges from 70-91%, based on our testing in the past.

The only real option, based on what he wants and what i see as practical, is a flex fuel tune. The engine harness and ecm he has are from a gen 3 vehicle. I was wondering if there was an operating system or gen3 ECM that has the capability to do a flex fuel tune?

I'm at the stage right now where i'm putting together a fuel system and i need to know if we're running 91 octane or if ethanol is still a possibility. It's not practical to do a straight E85 tune because he doesn't want to do 30-40 minutes of driving every time he fills up and doesn't have the ability to switch tunes on his own. i'm not sure what i can do for him here, just curious what the options are. It seems like running 91 octane is the only practical option at this point. 93 is only sold at one station in the area that i know of and its a longer drive than the E85 pump is.

thanks

[MikeOD]

There's a 2005 Avalanche tune in the repository that has functional flex fuel. You can use it in any 2003+ Gen 3 PCM (known as the P59, has blue and green connectors).

[2000_SS]

Oh sweet! So I just need to flash that OS and then wire up an inline ethanol sensor in the fuel system? Or is that a virtual sensor OS?

[2000_SS]

Checked out the pcm he brought me. ....green & blue connectors. I hooked it up on the bench top harness and is a P59 from a '05 Suburban. Flex fuel appears enabled as well....looks like we got lucky there.

So, please correct me if I'm wrong, but we just need to get a flex fuel sensor from the 05 suburban, rig it into the fuel system, and carry on with tuning? It should be nearly plug and play, right? This is my first rodeo with the flex fuel stuff....actually, my only ethanol experience has been in a blow thru carb turbo sbc 8.5 tire car...so I'm trying to be cautious here.

Thanks

[cobaltssoverbooster]

ac delco 12570260 or standard motor products FFS1 is the sensor you would run from the 05.
from a previous post:
Just wire the signal of the flex fuel senor to pin 56 on the blue connector. The other two wires are 12v power and ground. (A->Pin 56 Blue, B->+12vdc, C->gnd).
You change:
ENGINE > FUEL > OPEN & CLOSED LOOP > FLEX FUEL > FLEX FUEL ENABLE
ENGINE > FUEL > OPEN & CLOSED LOOP > FLEX FUEL > DEFAULT 38% (FROM A FF TAHOE BIN)
ENGINE > FUEL > GENERAL > AIR FUEL RATIO > STOICH AFR (COPY THIS TABLE FROM A FF BIN)
Enable DTC's p0178 and p0179 and set them to 1-mil on second error


the only issue is the sensor cost which is about $380-480 for the factory unit. I dont recall what the substitute is.

[gofastwclass]

the only issue is the sensor cost which is about $380-480 for the factory unit. I dont recall what the substitute is.

I'm using sensor 13577429 and harness 13352241 from Pace Performance. For less than $75 plus shipping you get the sensor and needed harness. There are at least two other similar looking small GM sensor options, but that one seems to consistently be the least expensive.

[cobaltssoverbooster]

I'm using sensor 13577429 and harness 13352241 from Pace Performance. For less than $75 plus shipping you get the sensor and needed harness. There are at least two other similar looking small GM sensor options, but that one seems to consistently be the least expensive.

Thanks much. Ill be saving that info

[2000_SS]

I was at a scrap yard today looking for engine mounts and stumbled on a flex fuel suburban....still had the sensor on it, the 12570260, and they let me have it and the engine mounts i needed for $78....can't beat that. I thought i was going to have issues with this project but it looks almost completely plug-n-play up to this point.

thanks for the info, guys.