PicoScope 7 Automotive
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New Holland T7.230
New Holland T7.230
I would like to get input as to the capture in this case,
background is the machine had a fault code of 3067 injector 4 malf.
engine had a definite misfire, the tech scoped the no. 1 & 4 injector (amp) and the ckp sensor
Inj. 1 has a nice defined pattern, injector 4 has a similar looking capture however it mirrors the no.1 but at a greatly reduced amp reading.
I suspect the capture on no.4 is just noise from no.1 and possibly other injector events as the ECU shutdown no.4 due to active fault.
As I mentioned, looking for input as to the pattern seen on the no.4 capture.
Thanks fore reading.
background is the machine had a fault code of 3067 injector 4 malf.
engine had a definite misfire, the tech scoped the no. 1 & 4 injector (amp) and the ckp sensor
Inj. 1 has a nice defined pattern, injector 4 has a similar looking capture however it mirrors the no.1 but at a greatly reduced amp reading.
I suspect the capture on no.4 is just noise from no.1 and possibly other injector events as the ECU shutdown no.4 due to active fault.
As I mentioned, looking for input as to the pattern seen on the no.4 capture.
Thanks fore reading.
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Steve Smith
- Pico Staff Member
- Posts: 1587
- Joined: Sun Aug 25, 2013 7:22 am
Re: New Holland T7.230
Hello and thank you for the post
Most certainly Ch A current clamp is detecting the operation of injector 1 (Ch B) via inductance
Given injector 4 was switched off, we now have this circuit behaving like an antenna in which the current clamp senses a number of high frequency “switching” events (i.e. other injectors)
Resting the current clamp on top of the engine (not around a cable) near injector 4 may also produce similar results
What is interesting is how defined injector 1 appears in the wiring for injector 4. This is most probably due to the arrangement of injector switching circuit within the ECU or injector driver assembly
The image above is how the signal would look (Ch A) using the COP probe resting on Injector 4
The COP probe being a capacitive pick up device, the current clamp is an inductive pick up device
Often injectors 1 and 4 are companion injectors for companion cylinders and may share a common power supply between them, so presenting an increased level of induced voltage to the current clamp about injector 4 wiring.
This may or may not be the case; it could simply be that the wiring for injector 1 and 4 run alongside one another within the engine harness, where there is a capacitive link between these cables
Below we can see how the current clamp around injector 4 wiring also detects other injection events but with a lower amplitude due to reduced signal strength
Such a response from a current clamp could be interpreted as "noise", yet how useful is "noise" in this scenario as we can detect other injection events using a single current clamp on one scope channel
I hope this helps, take care......Steve
Most certainly Ch A current clamp is detecting the operation of injector 1 (Ch B) via inductance
Given injector 4 was switched off, we now have this circuit behaving like an antenna in which the current clamp senses a number of high frequency “switching” events (i.e. other injectors)
Resting the current clamp on top of the engine (not around a cable) near injector 4 may also produce similar results
What is interesting is how defined injector 1 appears in the wiring for injector 4. This is most probably due to the arrangement of injector switching circuit within the ECU or injector driver assembly
- Image 1
The COP probe being a capacitive pick up device, the current clamp is an inductive pick up device
Often injectors 1 and 4 are companion injectors for companion cylinders and may share a common power supply between them, so presenting an increased level of induced voltage to the current clamp about injector 4 wiring.
This may or may not be the case; it could simply be that the wiring for injector 1 and 4 run alongside one another within the engine harness, where there is a capacitive link between these cables
Below we can see how the current clamp around injector 4 wiring also detects other injection events but with a lower amplitude due to reduced signal strength
- Image 2
I hope this helps, take care......Steve
Re: New Holland T7.230
Thank you Steve, appreciate the breakdown of the capture.