$11P flex fuel capability?

Converting To Delco ECU From Carby Or Other Injection Systems
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$11P flex fuel capability?

Postby BARBS » Tue Nov 28, 2017 1:41 pm

Hi all,

As per the title suggests, Is there the possibility of $11p having a flex fuel capability?
I run E85 at the track and premium on the street but to do so I have to either empty my tank and fill with the required fuel or I need to run 2 fuel systems and swap between the two.
It would be an awesome feature where I could simply fill the tank with whatever fuel is available and the tune sorts itself out.

Has this feature been looked into at all? If not, and someone would like to try to get it working, I would be happy to assist with testing for development etc.

Cheers,

Barbs

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Re: $11P flex fuel capability?

Postby antus » Wed Nov 29, 2017 7:19 am

See this thread viewtopic.php?f=7&t=4267&p=55882&hilit=flex+fuel#p55848

11P would be similar but VL400 would need to comment.I dont think it would be a small amount of work.
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: $11P flex fuel capability?

Postby BARBS » Wed Nov 29, 2017 7:30 am

Thanks Antus.
Ill hopefully hear from VL400 and if he is willing see if we could get something working. Im quite happy to invest in parts etc if someone is willing to invest time programming.
Thanks again.

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Re: $11P flex fuel capability?

Postby VL400 » Wed Nov 29, 2017 6:03 pm

The only spare analog input is a 0-25v input. Usable with something like the external gauge unit linked above.

But the code to get a proper flex fuel setup blending between tables is a little beyond the spare processing power of the ECU. Its fine to have either map A or map B as its one or the other, but with flex you would need to lookup many things twice then blend based on ethanol content. Its not as simple as a single overall AFR and spark modifier to do it properly. It just hasnt got the free cycles for all this, things over run already as it is.

If it was possible Id have it already.

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Re: $11P flex fuel capability?

Postby Dylan » Wed Nov 29, 2017 6:24 pm

Is that the same with 12P mate? I remember some talk a while ago about having the same AFR target's but the final pulse width modified depending on ethanol content.

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Re: $11P flex fuel capability?

Postby VL400 » Wed Nov 29, 2017 6:53 pm

Yeah same on 12p, more related to RAM in this case though. That discussion was before I had really used e fuel over a good 12 months of various conditions. Its not a linear calc, ie cranking in winter is more like 100-200% the required fuel not 30% like you would need on running afr. AE also is very different, mainly when cold.

Then spark, less at low loads with higher flame speed but can get more in when fuel knock limited on petrol.

A single ethanol multiplier would be good enough to get a race car running and on the trailer but not a true e flex setup on the street.

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Re: $11P flex fuel capability?

Postby Dylan » Wed Nov 29, 2017 7:00 pm

Thanks mate

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Re: $11P flex fuel capability?

Postby BARBS » Wed Nov 29, 2017 8:25 pm

Thanks VL400.
Ill put that idea to bed then. Much appreciated.

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Re: $11P flex fuel capability?

Postby BARBS » Thu Nov 30, 2017 12:00 pm

VL400 im sorry but my mind is still running mad on the flex fuel idea. Is there much room in the tune to setup the modifier tables if some of the unused coding is removed from the ECU? At the moment I have a tune with map A is ULP and map B is E85. The VE is the same for both but the commanded AFR and spark tables vary for each.
Would removing things like performance shift, adaptive shift, knock sensing etc make enough room to trial this? (Provided I can source a sensor to do the job)
If the modifier tables are a linear scale based on the flex fuel sensor measurement I'd think it would be rough enough to make it reasonably accurate.
Could the knock sensor input be utilised for the flex fuel sensor.?

Sorry to be a pain in the ar5e.

Barbs

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