PicoScope 7 Automotive
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Cylinder identification
Cylinder identification
Hi,
I have a 2006 Landrover TD5 15p engine code that is down in compression in one cylinder, I have captured the attached waveform but I am struggling a bit to identify the cylinder. The sync used is on cylinder no.1 injector connected to channel B and relative compression on channel a using voltage drop, I have a waveform overlay software but I am not sure of how to set it up since I am using an injector sync and not ignition.
The firing order of the engine is 1,2,4,5,3
Can anyone help;
a. explain how to use the software when working with injector sync on diesels
b. identify which cylinder is low on compression (I believe it to be no.4 but I may be incorrect)
Thanks in advance
I have a 2006 Landrover TD5 15p engine code that is down in compression in one cylinder, I have captured the attached waveform but I am struggling a bit to identify the cylinder. The sync used is on cylinder no.1 injector connected to channel B and relative compression on channel a using voltage drop, I have a waveform overlay software but I am not sure of how to set it up since I am using an injector sync and not ignition.
The firing order of the engine is 1,2,4,5,3
Can anyone help;
a. explain how to use the software when working with injector sync on diesels
b. identify which cylinder is low on compression (I believe it to be no.4 but I may be incorrect)
Thanks in advance
- Attachments
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- 20210816-0001-relative compression.psdata
- (201.05 KiB) Downloaded 258 times
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Steve Smith
- Pico Staff Member
- Posts: 1594
- Joined: Sun Aug 25, 2013 7:22 am
Re: Cylinder identification
Hello Burt and thank you for the post
Looking at the capture above I can see the confusion surrounding cylinder sync as our current clamp (Channel B) is responding to induced voltage events from neighboring or companion injectors.
Often these injectors may share power supplies or indeed circuitry within driver assemblies. The following forum post will help here viewtopic.php?p=100935#p100935
Looking at your capture below, assuming our current clamp is around injector number 1 (and our engine timing is correct) then our low compression surrounds cylinder 1
My reasoning behind this Burt is that your injection number 1 event (labeled above) aligns with peak compression (fall in voltage on channel A) at the correct point in time.
At 360° after cylinder 1 injection event, our induced spike (detected by the current clamp) falls between cylinder 4 & 5 peak compression events and not on a peak compression as you would expect
To be 100% sure, you could add power and ground to cylinder 1 injector (Use attenuation if using any other scope than a 4425 or 4425A). Here you will capture the voltage differential required for current to flow and clearly identify which of these injection events is cylinder 1 and which is an induced spike.
Remember, for current to flow there must be a voltage differential and there will be no voltage differential where the detected induced spike occurs
The following video from Ben will help too as another alternative method to ID your cylinder
https://youtu.be/EsJBOFzETjQ
I hope this helps, take care……Steve
Looking at the capture above I can see the confusion surrounding cylinder sync as our current clamp (Channel B) is responding to induced voltage events from neighboring or companion injectors.
Often these injectors may share power supplies or indeed circuitry within driver assemblies. The following forum post will help here viewtopic.php?p=100935#p100935
Looking at your capture below, assuming our current clamp is around injector number 1 (and our engine timing is correct) then our low compression surrounds cylinder 1
- Image 1
At 360° after cylinder 1 injection event, our induced spike (detected by the current clamp) falls between cylinder 4 & 5 peak compression events and not on a peak compression as you would expect
To be 100% sure, you could add power and ground to cylinder 1 injector (Use attenuation if using any other scope than a 4425 or 4425A). Here you will capture the voltage differential required for current to flow and clearly identify which of these injection events is cylinder 1 and which is an induced spike.
Remember, for current to flow there must be a voltage differential and there will be no voltage differential where the detected induced spike occurs
The following video from Ben will help too as another alternative method to ID your cylinder
https://youtu.be/EsJBOFzETjQ
I hope this helps, take care……Steve