I am dealing with a Porsche 911 964 with a 4.0l conversion. The previous tuner wired and installed the EMU Black. The fuel injectors were coupled to the ignition events as follows:
Injector 1 - Ign.event 1
Injector 2 - Ign.event 3
Injector 3 - Ign.event 5
Injector 4 - Ign.event 4
Injector 5 - Ign.event 6
Injector 6 - Ign.event 2
So, they inject in the firing order 1-6-2-4-3-5 once every 720°. The ignition is still a dual distributor.
The customer wants us to switch the injection to semi-sequential injection.
The injection has now been configured this way:
Injector 1 - Ign.event 1
Injector 2 - Ign.event 3
Injector 3 - Ign.event 2
Injector 4 - Ign.event 1
Injector 5 - Ign.event 3
Injector 6 - Ign.event 2
and additionally, “squirt twice” has been activated. Now, injection should occur every 360°.
What I notice in the logs now is that the injectors are being driven very quickly at 100% DC. Unfortunately, I don’t understand this…
The fuel injectors are now commanded twice every 720°, but that should not change the Injectors Duty Cycle (DC).
Could it be that the software is incorrectly displaying the DC with “squirt twice”?
Are you sure? If this is the right configuration, i really don’t understand why…
Thank you very much!
Edit:
I wired Injector 1 to an oszi and just measured the time between two injections. I attached a picture and the injector configuration.
So, it takes 100ms between two injections. The car idles at 1200 rpm, so one rev should take 50ms. As i understand it, the ECU injects only once per engine cycle.
Yes. But if you select squirt twice per cycle it will inject once per revolution.
It is useful if you are not running engine in full sequention (no cam sync)
The injection time is divided by two then to provide the same dose of fuel.
Yes exacly, this is how i understand it!
But given the picture above, the ECU isn’t injecting once per revolution. We have 100ms between two injections at 1200 rpm. One rev takes 50ms at 1200rpm. So one injection is missing. I tried to tick and/or untick the “squirt twice” Box and i get the same result every time…
I’m using Client Version 2.164A. Maybe i should downgrade and try again with an older Version?
It doesnt work with the end of injection timing.
End of injection timing works in 720 deg range (cycle).
If you are not synchronized with cam it cannot calculate correctly the full cycle angle.
Switch to inject at ignition event and everything will work correctly
While “you’re there”, maybe you should consider changing from distributor to distributorless ignition. I’ve been doing conversion using 2 coil packs from a V6 engine that are placed where the distributor is. Using stock ignition wiring. It’s easy conversion and you can forget about all the mechanical issues with the distributor for the future.
