Flex fuel L31 using the 0411

[Awest623]

So I've had this crazy idea ever since I swapped to an 0411. How can I make it run flex fuel?

Here's me thoughts:

I have a flex fuel OS out of a 2002 tahoe. The tune is set up for a 24x crank signal and COP ignition. The easy thing would be to swap to that and run the tune no problem, but $$$.

The tune has the option for a Lo Res crank signal, i.e. standard l31 4x. Obviously I would need to swap the injector pins to account for the different firing order of an LS. But the tune doesn't have the ability to run one ignition coil instead of 8. I wouldn't think the signals would be different between the two types of coils.
I believe that if I y'd all 8 ignition outputs on the ECU to the single wire controlling the stock coil it should work. I'd also run a diode on each ECU ignition output to make sure it doesn't fry itself.

I already have a spare 0411 in case it still frys it, and I need to pick up another ignition coil just in case.

What do y'all think about this endeavor?

I did try the OS with all tables copied over including the firing order. It started but wouldn't continue running and was obviously missing a few cylinders.

 

[Awest623]

Hold up. I was just thinking and duh..

It fired before. The computer uses completely different outputs for the COP ignition. That means it had to been sending a signal to the single coil. Maybe the Lo Res option enables not only a 4x crank signal but also a single coil signal. Leads me to think that all I might need to do is swap the injector wiring.

I'll keep y'all updated

 

[Awest623]

Ok. Did a little more digging, the l31 calibration DOES use one of the regular spark coil outputs. But I think it was running on more than one cylinder when I cranked it. Guess I'll find out tomorrow. I did some more looking and think I have the wiring figured out.

For the injectors I need to swap pin Blue #3 and Blue #4. And I need to swap Blue #43 and Blue #44.

IF I need to do anything with the spark, I'll y together Red #26,27,28,29,66,67,68,69. The l31 calibration only uses pin RED #26 for timing control.

An oscilloscope would make this easier to find out, but unfortunately I don't have access to one anymore

 

[L31MaxExpress]

Use a mexico Green/Blue PCM L31 calibration and turn flex fuel on. It will run in a DBC van PCM. My base files and PCMs were both 05s.

 

[stutaeng]

What about all the additional sensors/solenoids from the tank fuel lines to the engine? I recently pulled an L59 from a '03 Suburban and when I was under the vehicle I saw a bunch of stuff I don't have on my '99 Silverado (GMT800) 4.3 non-flex fuel. I did a little digging and looks like its sensors for the computer to figure out which fuel is flowing. I assume the computer then makes adjustments and suppose if all you run is flex-fuel, then you don't need them?

I don't know anything about flex-fuel so keep us updated on your progress.

 

[Supercharged111]

Is there a COS for the Tahoe OS?

 

[Awest623]

Use a mexico Green/Blue PCM L31 calibration and turn flex fuel on. It will run in a DBC van PCM. My base files and PCMs were both 05s.

I forgot that existed. Do you have a copy of the file in HPT format?

I also still wanna see if I can get this tahoe tune to work. Would save me $100 versus having to register a new ECU. And I already paid for the Tahoe file.

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[Awest623]

What about all the additional sensors/solenoids from the tank fuel lines to the engine? I recently pulled an L59 from a '03 Suburban and when I was under the vehicle I saw a bunch of stuff I don't have on my '99 Silverado (GMT800) 4.3 non-flex fuel. I did a little digging and looks like its sensors for the computer to figure out which fuel is flowing. I assume the computer then makes adjustments and suppose if all you run is flex-fuel, then you don't need them?

I don't know anything about flex-fuel so keep us updated on your progress.

The computer would use one ethanol sensor in line with the feed line to the engine. It measures alcohol percentage in the fuel and adjusts the mixture accordingly.

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[Awest623]

Is there a COS for the Tahoe OS?

Yes. It has all the regular COS

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[Awest623]

No luck with just swapping injectors.

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