Want to run E85?

[WHYTRYZ06]

nope... they did not

[gmh308]

nope... they did not

Unlikely to see the factory flex fuel listed as a calibration if it does not come from GM like that.

The later ones (E38/E67 etc) have flex fuel capability built in. EFILive has given more access to that with this release which simplifies things somewhat.

There are shops doing E85 cals on LS1's though. I would guess VE table etc and spark are the main areas to maximise the value of the E85.

An E38 flex fuel cal gives a reasonable idea of what GM is doing to support flex fuel.

[MN C5]

I've had several vehicles pre E38 or E67 that were Flex Fuel. Though it wasn't called that back in the day.

[gmh308]

I've had several vehicles pre E38 or E67 that were Flex Fuel. Though it wasn't called that back in the day.

Sounds interesting! LS1/LS6/LS2 ? Truck?

[dc_justin]

Did GenIII PCM's ever have flex fuel?

Yes. Going back as far as 2002 (maybe even 2001), you could get a flex fuel tahoe (VIN Z, L59 engine). It has an alcohol sensor to determine ethanol content as well as 33#/hr injectors as opposed to the 25#/hr injectors that the VIN T/LM7 non-FFV 5.3L has.

[gmh308]

Yes. Going back as far as 2002 (maybe even 2001), you could get a flex fuel tahoe (VIN Z, L59 engine). It has an alcohol sensor to determine ethanol content as well as 33#/hr injectors as opposed to the 25#/hr injectors that the VIN T/LM7 non-FFV 5.3L has.

Well it looks like the EFILive wizards have that covered too. At the very least, the L59 for 03 & 06 look like they have Flex Fuel options listed.

[WHYTRYZ06]

so can i use the ff option that efi has listed w/ build 72 on my gen 3 pcm or not?

[Chevy366]

Asked a guy who just got through building his 528 if he was going to run Ethanol , he looked at me and laughed , 800+ hp and 2 stage 500 shot Nos , said he would stick to race fuel .
So at what point does Ethanol make it's way into high horsepower engines or will it ever , or has it already ? Lingenfelter has a Corvette that a couple years ago was the first E85 Vette .

[GMPX]

If you were going to run E85 all the time then there is no great wizardry apart from doing the total retune to suit the E85, it only gets confusing when you want to be able to throw in normal fuel and have the ECM adjust accordingly.

The LS1 PCM's used a real sensor in the fuel line to measure the ethanol content (they are about $400!!), the later Gen-IV's used software for ethanol estimation saving GM the need for the $400 sensor. Please don't ask me to explain how that works! I don't really know apart from they monitor the fuel level sensor and O2 sensor trends and somehow calculate the ethanol percentage from that. It would be interesting to know just how accurate it was.

Cheers,
Ross

[gmh308]

If you were going to run E85 all the time then there is no great wizardry apart from doing the total retune to suit the E85, it only gets confusing when you want to be able to throw in normal fuel and have the ECM adjust accordingly.

The LS1 PCM's used a real sensor in the fuel line to measure the ethanol content (they are about $400!!), the later Gen-IV's used software for ethanol estimation saving GM the need for the $400 sensor. Please don't ask me to explain how that works! I don't really know apart from they monitor the fuel level sensor and O2 sensor trends and somehow calculate the ethanol percentage from that. It would be interesting to know just how accurate it was.

Cheers,
Ross

Ta Ross,

You guys have made it easier though to "switch" Ethanol % tunes.

If anyone is interested in how GM's Virtual Fuel Sensing works, and you have some time, take a peek at the patent:

GM-VFS US Patent 7159623.pdf

Accuracy is discussed in the patent.

At a guess, with E0 and E10 using the same tuning, within 5 or 10% accuracy would be ok.

Cheers!