1.6HDi DV6C 9HL injector voltage - what is normal?

[mcdos]

It would be really helpful if someone with a vehicle having a 1.6HDi (DV6C 9HL engine) with diagbox could take a look at the control voltage of the injectors bank 1 signal in their ECU (HDi_SID807_BR2) - when the engine is ticking over. I'm really struggling to find out what the norm for this is. My ECU indicates 225-228Volts at idle.

This may be normal, but if it is too high, it could be the source of some random faults I'm seeing and would likely damage any replacement injectors.

[saskak]

It would be really helpful if someone with a vehicle having a 1.6HDi (DV6C 9HL engine) with diagbox could take a look at the control voltage of the injectors bank 1 signal in their ECU (HDi_SID807_BR2) - when the engine is ticking over. I'm really struggling to find out what the norm for this is. My ECU indicates 225-228Volts at idle.

This may be normal, but if it is too high, it could be the source of some random faults I'm seeing and would likely damage any replacement injectors.

I tried with my 9HX to look at the control voltage of the injectors bank 1 signal, but could not really find where to measure this from. I went through all measurement options on my diagbox (ECU and BSI), but nothing related to injector control voltage. What is the exact name of the measurement, probably better if you post a picture.
Well, mine is 1.6HDi, but the M59 and 9HX, so a bit older than yours, but thought that might help looking at what it shows. It might be only for the B9.
Is your measurements from Diagbox/Lexia or some sort of OBDII thing?

[brajomobil]

It is best to connect ordinary voltage meter, put it on AC and measure on injector.

Check pic3 from this page. It is around 100V.
https://markstammersdiagnostics.com/refe...injectors/


Best regards,
brajomobil

[mcdos]

It would be really helpful if someone with a vehicle having a 1.6HDi (DV6C 9HL engine) with diagbox could take a look at the control voltage of the injectors bank 1 signal in their ECU (HDi_SID807_BR2) - when the engine is ticking over. I'm really struggling to find out what the norm for this is. My ECU indicates 225-228Volts at idle.

This may be normal, but if it is too high, it could be the source of some random faults I'm seeing and would likely damage any replacement injectors.

I tried with my 9HX to look at the control voltage of the injectors bank 1 signal, but could not really find where to measure this from. I went through all measurement options on my diagbox (ECU and BSI), but nothing related to injector control voltage. What is the exact name of the measurement, probably better if you post a picture.
Well, mine is 1.6HDi, but the M59 and 9HX, so a bit older than yours, but thought that might help looking at what it shows. It might be only for the B9.
Is your measurements from Diagbox/Lexia or some sort of OBDII thing?

[mcdos]

Mine is a PHL engine and I used diagbox to find our what the ECU was doing.
Within the ECU measurement variables there is one called "Control voltage of the injectors bank 1"  which is between 225 and 228V on idle.
I was able to plot the measurement from the stored data as below. 
I'm assuming the control voltage is the peak voltage applied to the injectors ...
   

[mcdos]

It is best to connect ordinary voltage meter, put it on AC and measure on injector.

Check pic3 from this page. It is around 100V.
https://markstammersdiagnostics.com/refe...injectors/


Best regards,
brajomobil

Yes, I came across that site and those measurements are what set me off asking this question. If you look at the peak voltage on his scope plots, its around 120V and my ECU is indicating 230V as the control voltage.  
An ordinary voltmeter on AC won't give you a reliable reading, just an indication that something is going on and perhaps the ability to compare injectors across the four cylinders.  Voltmeters are generally designed for measuring sinusoidal AC waveforms (unless they are true RMS meters), but a sequence of short duration square wave pulses such as is applied to the injector this will probably produce unpredictable results in a normal voltmeter The issue I'm trying to sort here is what the normal magnitude of that peak voltage is on this vehicle. I've been on to the injector manufacturer and they won't provide any clues either..... THe plot I'm referring to is the one with the SID807

[brajomobil]

Then in your case it is better to take scope and measure.

Best regards,
brajomobil

[mcdos]

Ok, so I have now carried out scope voltage and current measurements on the car and can confirm that the control voltage reported in diagbox is not the voltage which ends up at the injectors:
    Injector 1 (suspect)
    Injector 4 (assumed ok)
Here we can see that the peak voltage at the injectors is around 117V. So I assume the internal ECU power electronics structure is such that the injector peak voltage is limited to approximately half the value reported in diagbox. So my initial concern was unfounded. Occupational hazard of trying to learn as you go along....
 
Reassuringly, my scope plots are actually quite similar to the one published by markstammersdiagnostics. 

Needless to say, there is very little obvious difference in the scope traces between the "failing" injectors and the "good" injectors so its still a difficult call as to what's actually going on. 

Intermittent faults are just the worst!