high voltage injectors (HDi diesel)

[ecoxantia]

Thanks for the reply dcb, having had a look at the code you have my utmost respect!!

Pressure - red line above- this is the pressure of a common rail - a foot long forged steel pipe in other words - some way from the injector itself. I wouldn't have thought its any kind of pwm, certainly not read about anything like that. Basically there's a 3 piston pump that provides the pressure and the pressure is as high as the pump can manage without wasting too many kw! More recent HDi engines apparently have even higher rail pressures.

So I think the blips are a pressure wave from the injector opening and closing. There's one for the pre-injection and one for the main injection - interesting but a "red herring" for my purposes.

20 volts was measuring away from the duino, in the engine bay!! 20V is the limit of my scope...

Thanks for the atmega on/off voltages - shame that the decay is quite slow (shallow slope) and I wonder if that's why at idle the us displayed varies quite a lot.

I agree that the duino does not seem to be measuring what I want. I'll try some signal conditioning and see what happens. It may only be measuring the pre injection, I don't think the scope always shows the rapid drop in signal.

I'm doing analogread on the red line, the rail pressure, by the way. I'll check that out on the bench with a power supply next.

[dcb]

re: longer injector times at idle. It may be that you have to use the other injector lead too. Or that somehow we are looking at the low side of the pulse. But it could be that it is positively switched also.

You might try changing the code for a positively switched injector and see if that helps:
i.e. change
attachInterrupt(0, processInjOpen, FALLING);
attachInterrupt(1, processInjClosed, RISING);

to
attachInterrupt(0, processInjOpen, RISING);
attachInterrupt(1, processInjClosed, FALLING);

[ecoxantia]

Thanks, now I think I need to get a more comprehensive picture of what's going on here; scoping and recording both lines for example. I think you may be right about the low side of the pulse...

[ecoxantia]

I've swapped RISING and FALLING as you suggested and it is at least giving more "uS" for more accelerator! Promising. No time now to set up the scope.

Won't know more until I road test it tomorrow...

[ecoxantia]

...well sort of.

After realising that my injectors are positively switched, dcb's suggestion of swapping RISING and FALLING in the code, at least gets me sensible data for injection timing.

In addition I have reduced the voltage of the injector signal to 3V peak, with a potential divider.

I still have not managed to implement my common rail pressure adjustment, some work is needed on the bench to find out what's wrong there. At the moment it's all commented out.

So at present I have a device that works well at low speeds. At high engine or road speeds, where the pressure makes a significant difference the amount of fuel injected, things are not so good; I get the same mpg at 60mph or 80mph!

I have found that coasting out of gear is better than coasting in top gear, at least according to hdiguido based on v0.70...