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G4x multipoint injection timing


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Hi folks,

I am tuning a engine turbo , it is a 1.4L 4 cilinders from renault 11 Turbo, with custom injection converstion to 4 injectors.

I have the car running quite nice right now, on modelled multipoint injection and  fuel rate 2.

I have had to tune injection angle for each rpm and load because if  i set a low value here engine misfire and run badly.

My question is why on multipoint (semisecuential) i have to tune this value, on other ecus it was not necesary, i always though injection timing only was tuneable on full secuential injection not on semi.

how can ecu know the correct angle of injection without a cam sensor?

i let here my tables and configuration, injection angle is set to end of injection.



end of injection.GIF

fuel main.GIF

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In many ECU's in batch fire mode the injector timing is locked at a fixed point.  In G4X it does exactly what you tell it to do.  You are right though, it would generally make little difference to how the engine runs in multipoint group mode.  it may hint that your injector spray pattern is poor so timing makes a big difference to how much vapor Vs liquid fuel gets into the cylinder. 

12 hours ago, kirchoff said:

how can ecu know the correct angle of injection without a cam sensor?

It doesnt, it only knows position within 360degs.  So Inj timing of 390BTDC is the same as inj timing set to 30BTDC.  

In the captures below, trigger offset is 0 and ign timing is zero, ign mode is wasted spark, so 0BTDC is the first falling edge after the trig 1 missing teeth, you can see in the first pic the end of injection and spark both occur in the same place.  

Inj timing 0BTDC:



Inj timing 390BTDC (30BTDC would give same result):



Inj timing 550BTDC (190BTDC would give same result):



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