Flex Fuel - Master Enable/Disable

[michael55123]

I tried it on my 08 STS Northstar and set the switch to enable and filled up with E85. The AFR adjusted correctly and the engine run fine but then I dedected rough shifting. Looking at the scanner I saw that the delivered torque numbers were quite high. So I think the calculation of the delivered torque must be misscalculated.
So I set it back to disable, changed the main AFR for the E85 and the car run fine.
Is there a (hidden) table which has to be changed so that the PCM calculates the torque correctly?

Not the case on the G8 GT tune. I threw the switch on, started the car with the default stoich with e85 in the tank and the trims went crazy but the commanded AFR didn't move. So I thought it might have something to do with filling up, or the car knowing there's more fuel in it to start the algorithm or process, but this wasn't the case. Re-Filled it up and threw the tune with flex fuel enabled on it, no change either. So I'm guessing I'm missing some cables/calibrations? I'd guess a 09 Gen IV E38 pcm has the capability of doing this?

[swissgtp]

Re-Filled it up and threw the tune with flex fuel enabled on it, no change either.

I think you have to load the tune with flex fuel enabled on first and then fill it up. As soon as the PCM dedects a change of the fuel level it will calculate the afr based on the input of the oxygen sensors or STFT.

[michael55123]

I think you have to load the tune with flex fuel enabled on first and then fill it up. As soon as the PCM dedects a change of the fuel level it will calculate the afr based on the input of the oxygen sensors or STFT.

I'll try switching it on at the pump, flashing it, running the car for a minute. Then I'll turn the car off, fill it up, and see what happens? Is this what I should be doing?

[camaro1]

pretty sure it has been posted that this is just to disable/turn off flex fuel,, i really dont think just one switch parameter will enable the system

[Higgs Boson]

There is no system. Not everything available to change in HPT is installed on every car. For instance, I can adjust the TCC and shift speeds of my 2001 Z06 all day long but the car will never have an automatic transmission.

[Higgs Boson]

BTW, do the Flex Fuel trucks come with a flex fuel sensor and actually use the ethanol % stoich table still? I heard/read GM isn't putting the sensor in the trucks anymore.

True/False?

[swissgtp]

I'll try switching it on at the pump, flashing it, running the car for a minute. Then I'll turn the car off, fill it up, and see what happens? Is this what I should be doing?

Correct.

[michael55123]

BTW, do the Flex Fuel trucks come with a flex fuel sensor and actually use the ethanol % stoich table still? I heard/read GM isn't putting the sensor in the trucks anymore.

True/False?

Corrent, they use the "virtual sensor" now.

[michael55123]

Correct.

No such luck. Missing more than just the enable disable.

[Higgs Boson]

How does the virtual sensor work?

I'll never run E85 in the truck so what happens if I disable Flex option and set all the stoich table values to 14.22?

[michael55123]

Interesting info:

Flex Fuel Option

{B0178} Flex Fuel Option Yes
{B0184} Flex Fuel Sensor Type Actual Sensor
{B0185} Flex Fuel Default Percentage 50 %
{B0186} Flex Fuel Sensor Diagnostic Enabled
{B0187} Flex Fuel Diagnostic Run Time 3.0 Seconds

All these tables, and Pin 40 on the E38 ECU seems to be where the flex fuel sensor goes. If we had access to these tables, could we add the sensor?

[Bill@HPTuners]

Interesting info:

Flex Fuel Option

{B0178} Flex Fuel Option Yes
{B0184} Flex Fuel Sensor Type Actual Sensor
{B0185} Flex Fuel Default Percentage 50 %
{B0186} Flex Fuel Sensor Diagnostic Enabled
{B0187} Flex Fuel Diagnostic Run Time 3.0 Seconds

All these tables, and Pin 40 on the E38 ECU seems to be where the flex fuel sensor goes. If we had access to these tables, could we add the sensor?

These are the ones I put in queue to be added for E38's, theres a couple of others as well. Won't be for several weeks though as we're already backed up with work as it is.

[juyanith]

Okay, I have a dumb question. Does changing the value of stoich in the 0% column do anything on a non-flex fuel vehicle (an '07 Z06 in this case)? I only ask because we get the typical "up to 10%" gas in most all the pumps around here and obviously that's not going to be 14.67 or even consistent from one fill to the next.

Since this amount varies and the car has no way to know it must be relying on fuel trims to adjust. For purposes of tuning and optimum performance it's somewhat important though. This is what I'm thinking if I've got this right in my head: If the car was tuned for "pure" gasoline and you put E10 in the tank, it would presumably be adding fuel. If positive LTFT values are added at WOT this would then correct bringing the car back into the best power range. Obviously this wouldn't be instantaneous, but would take some time for the LTFT values to adjust. Do I have that straight?

[DSteck]

These are the ones I put in queue to be added for E38's, theres a couple of others as well. Won't be for several weeks though as we're already backed up with work as it is.

Bill, will these parameteres being added allow the flex fuel options to work? I am not really interested in using an alcohol sensor, but more interested in just being able to apply 5V to a PCM pin and be able to use alternate spark and fuel options.

[Bill@HPTuners]

Bill, will these parameteres being added allow the flex fuel options to work? I am not really interested in using an alcohol sensor, but more interested in just being able to apply 5V to a PCM pin and be able to use alternate spark and fuel options.

In theory it should work fine for setting up the pcm for use with E85, other than that its a stretch though.

[DSteck]

In theory it should work fine for setting up the pcm for use with E85, other than that its a stretch though.

If EFI Live can do it, then I have faith in HP Tuners.

Like I said, I just want the option to toggle between two settings.

[camaro1]

id like to try it with the sensor and have a true flex-fuel tune.

[Bill@HPTuners]

If EFI Live can do it, then I have faith in HP Tuners.

Like I said, I just want the option to toggle between two settings.

UGH, I just read through that thread, yeah I guess it should work. I'll try to make up a similar how to post once the tables have been added to all the different operating systems.

[DSteck]

UGH, I just read through that thread, yeah I guess it should work. I'll try to make up a similar how to post once the tables have been added to all the different operating systems.

have I told you lately... That I love you?

[Mr. 2008 SS]

Man you guys are reading my mind!!
In theory it should work fine for setting up the pcm for use with E85, other than that its a stretch though. Bill your above statement really make me think but I will try small changes first


The E-85 set up TABLES will be very cool
2008 TBSS AWD K@N ,Cat back
Meth
Turbo soon
Heads
My next buy a Wide Band O2 w/data logging
Then I will make small tuning changes in the fuel tables
Thanks,
Mr. 2008 SS