MoTeC Global Forum

Ok here's one that has got me stumped, need to trim one of of the injectors ( ind cyl trim ) with temp compensation.
I have tried the fuel comp user tables but only 2 axis tuning availiable, anyone got any ideas ?

Hi 20B,

If I understand correctly, you want to adjust the amount of fuel delivered based on engine temperature on one injector only??

You can compensate fuel delivery on each injector based on any two channels using the individual cylinder trim 3D tables.

Are you currently using the individual cylinder trim tables for anything??

Darren,
Yes I'm already running trims in the individual cylinder 3D table, I have one sticky injector that runs lean on cold start up to about 60 degrees then it's fine. I wanted to add some comp fuel based just on engine temp to that one injector. Can I use user comp 1 and user comp 2 in the fuel adjust settings to do something ?
It's just a bit of a band aid solution to get it fixed whilst I source some replacement injectors.

Ok, i thought that must have been the case.

No, the only compensations that happen on individual injectors is the individual cylinder tables, and the individual trim fixed value. All ather compensation values are applied to all injectors.

Saying that, there is still a way, but it will depend on what you are already compensating on.
You can use a spare table to create a value that mixes engine temp with one of the channels already on the individual cyl table. The table is filled out so when the result is used on the indvidual cyl table more fuel is added when cold, but otherwise the fuel trim is the same as if the other channel is used directly. it may not be possible to achive the exact fueling required, but could come close.

Let me know if you need more help.

Cheers,

Darren,
Sounds like that would be perfect, could you post up an example file for download so I can copy what you have done to make it work and adjust the settings for my specific situation.
Thanks

Like i said, it really depends on the comps you're already doing, if it will even work, and also on what other resources you have available.

If you want you can send your config through to me at darren.reynolds@motec.com.au and i'll take a look.

Just for the others following this thread,

20B sent me his configuation, unfortuantly he is using all his outputs meaning there was no spare tables to use that don't intefere with normal operaion.

The way I intended on doing it is to put the individual trim table values into a different table with the right range, assign the axis the same so the result of the table is what the trim would be, then use this on one axis of individual trim table. In the individual trim table you can set the axis value to say -20 to 20% and the table value to the same, so the result of the other table is effectively passed through to the individual cylinder.
That leaves an axis free to put engine temp on there, so when the engine is cold you can add fuel.
Here is an example of the ind trim table, X axis is engine temp, Y axis is the other table with the fuel trim on it.

Code: Select all

Other/temp   -20    60    65   150
-20          -15   -15   -20   -20
 20           25    25    20    20


This table would add an extra 5% fuel to the injector under 60 deg engine temp, and no extra fuel above 65deg, without altering the existing trim.

If 20B can free up an output then he can assign the output as an aux table and use the duty cycle result as the y axis (other) in the table.