Jump to content

Flex fuel tuning


MarcusP

Recommended Posts

So the fuel charging coefficient for 91 octane which is e10 here is set to 10. On the flex side we are at e80 and the fcc is set to 30. 
 

the 91 tune is petty set, should I change the fcc for flex to 10 to get the numbers to line up?  
 

Link to comment
Share on other sites

It is most likely the injector flow rate setting that is incorrect.  Was the injector flowrate tested with both fuels or do you have the same flowrate entered for both fuels?

If flowrate is unknown I normally set fuel table 2 to the same numbers as table 1 (or leave it turned off) and then adjust the flowrate up or down until the fuel mixture is in the ballpark at medium RPM/load.  Then in some cases you may need to make some small tweaks in the 2nd table to get mixture to track well over all condition. 

Link to comment
Share on other sites

Just now, Adamw said:

It is most likely the injector flow rate setting that is incorrect.  Was the injector flowrate tested with both fuels or do you have the same flowrate entered for both fuels?

If flowrate is unknown I normally set fuel table 2 to the same numbers as table 1 (or leave it turned off) and then adjust the flowrate up or down until the fuel mixture is in the ballpark at medium RPM/load.  Then in some cases you may need to make some small tweaks in the 2nd table to get mixture to track well over all condition. 

I’m running the older ID 1700x injectors. I only find one flow number on their site and it’s not fuel specific that I can tell. 
 

I have both fuels  set to the same number

Link to comment
Share on other sites

19 hours ago, Adamw said:

Yeah, ID only test with a fluid that is something close to gasoline in terms of physical properties.  

Do you have smaller VE numbers all over table 2 or have you only tuned around idle area so far?

This is still very rough on the e80 side but you will get an idea.

 

Link to comment
Share on other sites

Ok, I potentially see some of the problem.  You have all the multifuel properties (density, stoich ratio etc) set up for pure ethanol, but your multifuel blend ratio table is set up to use 100% of the pure ethanol properties for anything over 80% Eth.  

If you want to tune the 2nd VE table using E85 rather than pure ethanol, then it would be best to change those multifuel properties to represent E80 or E85 instead of E100.  You could then leave the blend ratio table as is.  

Suggest values about 0.7824 for density, 0.001069 for density temp coef, 9.8 for stoich ratio.   

 

 

 

Link to comment
Share on other sites

22 minutes ago, Adamw said:

Ok, I potentially see some of the problem.  You have all the multifuel properties (density, stoich ratio etc) set up for pure ethanol, but your multifuel blend ratio table is set up to use 100% of the pure ethanol properties for anything over 80% Eth.  

If you want to tune the 2nd VE table using E85 rather than pure ethanol, then it would be best to change those multifuel properties to represent E80 or E85 instead of E100.  You could then leave the blend ratio table as is.  

Suggest values about 0.7824 for density, 0.001069 for density temp coef, 9.8 for stoich ratio.   

 

 

 

I’ll try that in the morning. Thank you!

Link to comment
Share on other sites

5 minutes ago, koracing said:

Is it not advisable to simply change the blend ratio tables to only use 100% of table 2 when Ethanol % is 100% interpolating the values from zero to 100 and leave the rest alone? 

I figured you should set table 1 at the lowest E and table 2 at the highest E you plan to run and let it blend between them. I’m never going to run e100 

Link to comment
Share on other sites

That's fine and while you are tuning I agree that is the simplest way to set it up.  I know the customer may in the future desire to buy E0 or E90 or something after I'm done with the car and so in principle I like to know the ecu could handle any mixture above or below the original tune points when the tune is finalized.

Link to comment
Share on other sites

1 minute ago, koracing said:

That's fine and while you are tuning I agree that is the simplest way to set it up.  I know the customer may in the future desire to buy E0 or E90 or something after I'm done with the car and so in principle I like to know the ecu could handle any mixture above or below the original tune points when the tune is finalized.

Makes sense. E0 isn’t available here and e85+ can only be bought as race fuel. Neven e85 from the pump is hard to find. 
 

I would think that if your e10-e85 tune was on point the ecu can handle corrections for e0 and e90 without a hiccup. 

Link to comment
Share on other sites

6 hours ago, koracing said:

Is it not advisable to simply change the blend ratio tables to only use 100% of table 2 when Ethanol % is 100% interpolating the values from zero to 100 and leave the rest alone? 

Not If you are only running E85 when tuning table 2.  You really want to isolate any error due to blending from the primary fuel properties and table.  If you want to be able to blend all the way to E100 then you should really tune on E100.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...