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JohnRambo

Flex fuel on G4

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Hi

Does the G4 support running flex fuel?  I have a RB engine with ITB's, at my main fuel table is TPS/RPM and we have used the 4D table for MGP.

Can I use the 5D fuel and  4D ign for %ethanol.  I couldn't see an option for a separate boost table to use with %ethanol.

The car is currently tuned for 98.

Thanks in advance

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The G4 ECUs can do flex fuel using 4D and 5D tables (as you have suggested). Yes, use the 5D table for fuel, and 4D table for ign.

For boost there is no overlay tables, however one way to do it is to use closed loop boost control. Use the Wastegate DC% table to get your boost where you normally have it, then use the Boost target table with the axis set to Engine speed and%ethanol.

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Set active edge as Falling.

Thank You Scott. I have another question. When the sensor is all wired in, Can i Display both the E% and the Temp using a Digital Gauge on PC Link? Will The temp display just wired into the DI? or do i have to splice an AN V into the sensor as well? When i create a Digital Gauge for the Sensor, It shows the DI Frequency (HZ), and im guessing that reads the E%, but how do i get it to display the Temp as well?

Edited by Weldon

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Hi.

Yes the ECU will detect both temp and %E and you can configure a display to suit both.

 

Ok so i only need to wire it up to the DI correct? And how do i display the Temp?  I know that the Frequency displays the %, and the Status displays that its active, but those are the only options that i see...

 

EDIT: Nevermind i found the Ethanol % and Temp in the Fuel drop down menu. I was looking in the DI menu.

I appreciate your help Scott. thank You

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It's really crazy what I'm finding, you cannot at all apply a blanket adjustment (ie 0-33% 2D overlay table). To reach the same lambda target, It seems that it wants less in vacuum and more in boost, so far this is what I have come up with, what are others finding?

flex.png

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It will be interesting to see what others have to say. On our G4+ range of ECUs we have gone for  more complex method of fuel control for ethanol-petrol blends. One tune is done on petrol, then another is done on the maximum level of ethanol to be used. The ECU then blends the two tunes based upon the current level of ethanol.

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It will be interesting to see what others have to say. On our G4+ range of ECUs we have gone for  more complex method of fuel control for ethanol-petrol blends. One tune is done on petrol, then another is done on the maximum level of ethanol to be used. The ECU then blends the two tunes based upon the current level of ethanol.

whats the difference between how its done on a G4 vs G4+? 

I thot you tuned for Petrol, and then for E85, and the maps blend depending on the ethanol content that is read by the Sensor.

I didnt know there was another way. 

Edited by Weldon

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Only way is to use the 4d 5d ign fuel maps with %e on an axis.  I have a thread here somewhere about boost control onthe g4 with variable ethanol 

i would definitely like to read the boost control thread. My tuner mostly deals with the Cobb AP , but i dont know how many times hes tuned for flex fuel with a Stand Alone EM. I would just like to be prepaired for whatever may happen. 

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One way to do the boost control is to set the Wastegate % DC table to have axis of Engine Speed and Boost Target. Then set the Boost Target table to have axis of Engine Speed and % Ethanol.

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Getting the fuelling and ignition timing right is more important and so far in my short experience, it's too far out of whack wandering further than 20% past the base tune when every table is limited to 1 axis because E% must be on the other...., I'm worried that if I satisfy the E% vs MGP map for 7000 rpm column that it would flood the shit out of the 3000 column for example, and If i tried to take it off with an extra E% vs RPM map it excessively lean out the cruise zone

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