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fuel map maxed out


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hey i have a small issue with my sr20det have started to tune it today and i have noticed i need to get more fuel but the fuel map wont let me it is at 150. am i missing somthing to get the fuel table down so i can add more.

 

the car has 1650cc injectors on e85 so they should be big enough.

 

any help would be good 

 

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Change the stoich value to 9.8, this will bring you pretty close to correct.  Unless you have flow tested the injectors specifically with e85 then I would make a guess and change injector flow rate to about 1500cc.  Most injectors will flow 10-15% less ethanol than their quoted petrol/n-heptane flow rate.

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I'm running the Asnu equlivant injectors with a spray plate and found 8% less flow with E85 during flow testing. Can u post a pick of your dead times and I'll compare it to what I worked out. If ur dead times are too low the VE numbers with need to be alot bigger.

 

Best way to tell if the dead time is close in modelled mode is to drive in a area of the map around 2.5ms pulse width. Should be in linear area of injector. Tune the fuel cells so it match the afr target table I tune to .9 Lambda for testing. Now in the afr target table request a change to Lambda 1 afr should follow. Now request a change to .8 afr should follow. If not change all the dead time valves by the same amount so the afr tracks the requested new afr target. 

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  • 2 years later...
On 8/12/2018 at 6:09 AM, Adamw said:

Change the stoich value to 9.8, this will bring you pretty close to correct.  Unless you have flow tested the injectors specifically with e85 then I would make a guess and change injector flow rate to about 1500cc.  Most injectors will flow 10-15% less ethanol than their quoted petrol/n-heptane flow rate.

Hi, it looks like I will max out fuel table also in a rb26 engine. Injectors are id1000 at 4 bar base fuel pressure which ID says 1180 cc and correct dead times and on idle VE numbers are about 70%. Stoich value is 14.7 but this is correct also because of pump fuel. How can I lower the values to around 50? 

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70% isnt too far away from where I would would be happy.  I often end up with a VE of around 60 for idle.  But I wouldnt expect that is so high that you would max out the fuel table.  Are you monitoring differential fuel pressure?  

If you need to reduce your VE numbers then you need to make the ecu think there is less fuel flow or more air flow than there actually is.  So you can reduce injector flow rate setting, reduce base fuel press setting, or increase engine capacity.  No real advantage on which one you change.

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