PicoScope 7 Automotive
Available for Windows, Mac, and Linux, the next evolution of our diagnostic scope software is now available.
What's up with the cam sensor...
What's up with the cam sensor...
2011 Citroen Dispatch 1.6HDi
Intermittent Hard start, had at least 3 cam sensors, just had the engine out to drill out the cam sensor bolt and re-fit a new sensor. Still setting intermittent sensor codes.
I get to it and scope the CMP sensor wire at the ECU as it's impossible to get to. This is what I get when it's running :
As you can see the two notch pairs seem to be normal, then an extra appears - I though this was a crack in the reluctor, but then the first of the pair almost disappears. - Always the same notch goes and always the same position for the extra one - though in one sample I found the entire pair missing.
I don't think it's air gap as it is too repeatable (plus multiple replacements). I assume the CMP sensor must only be used for starting as it runs OK.
I'm getting the engine stripped off so I can get a borescope in the hole but place your bets ...
Intermittent Hard start, had at least 3 cam sensors, just had the engine out to drill out the cam sensor bolt and re-fit a new sensor. Still setting intermittent sensor codes.
I get to it and scope the CMP sensor wire at the ECU as it's impossible to get to. This is what I get when it's running :
I don't think it's air gap as it is too repeatable (plus multiple replacements). I assume the CMP sensor must only be used for starting as it runs OK.
I'm getting the engine stripped off so I can get a borescope in the hole but place your bets ...
- Attachments
-
- 20221118-0001 citroen dispatch CKP CMP CSR ok extract.psdata
- (4.63 MiB) Downloaded 150 times
Re: What's up with the cam sensor...
Hello.
On the PSA HDI 1.6 engine, as a rule, there is a standard signal form of the camshaft sensor reference.
The chaotic change in signals can only be explained by a malfunction of the sensors.
There is also a very rare case of strong magnetization of the reference point itself.
If you do not see a problem with the disk through the borescope, then you will return to the quality of the sensors again.
All this is easy to check.
Connect the power supply to the sensor.
In order for the signal to be read normally, the signal wire must be connected to the power supply via a resistor with a nominal value of about 1 KOm.
Scroll a homemade metal sector past the end of the sensor with a drill.
Make sure that at different rotational speeds ,the signal has even rectangular pulses.
On the PSA HDI 1.6 engine, as a rule, there is a standard signal form of the camshaft sensor reference.
The chaotic change in signals can only be explained by a malfunction of the sensors.
There is also a very rare case of strong magnetization of the reference point itself.
If you do not see a problem with the disk through the borescope, then you will return to the quality of the sensors again.
All this is easy to check.
Connect the power supply to the sensor.
In order for the signal to be read normally, the signal wire must be connected to the power supply via a resistor with a nominal value of about 1 KOm.
Scroll a homemade metal sector past the end of the sensor with a drill.
Make sure that at different rotational speeds ,the signal has even rectangular pulses.
- Attachments
-
Re: What's up with the cam sensor...
Hi Vasek
Thanks again for your input, I had been trying to find a reference WF so that's really helpful - though the CMP i have is inverted from that sample.
I'm no stranger to problems being the "new" parts, however the pattern does not seem to be chaotic, with one exception in 5 mins of running there is a pattern of the extra thin notch and the missing first one of the pair that is a problem. {EDIT} - looked at more samples and it does seem to be more chaotic than I thought.
I did wonder about magnetisation - as you say very rare, I wonder if the TA330 Keyless entry signal detector would pick it up, obviously would need a similar known good as it's a big call.
Another great emulator idea, you have really made me think more about using emulation - especially with the increasing problems with new parts ( I have acquired 4 bulb holders and 10w bulbs for the Toyota) . I have waved a spanner in front of a hall sensor before to check operation, but a hole cutter on a drill would be a much better test. If I do it off the car is the sensor wire connected to power or ground via the resistor ?
Thanks again Vasek.
Thanks again for your input, I had been trying to find a reference WF so that's really helpful - though the CMP i have is inverted from that sample.
I'm no stranger to problems being the "new" parts, however the pattern does not seem to be chaotic, with one exception in 5 mins of running there is a pattern of the extra thin notch and the missing first one of the pair that is a problem. {EDIT} - looked at more samples and it does seem to be more chaotic than I thought.
I did wonder about magnetisation - as you say very rare, I wonder if the TA330 Keyless entry signal detector would pick it up, obviously would need a similar known good as it's a big call.
Another great emulator idea, you have really made me think more about using emulation - especially with the increasing problems with new parts ( I have acquired 4 bulb holders and 10w bulbs for the Toyota) . I have waved a spanner in front of a hall sensor before to check operation, but a hole cutter on a drill would be a much better test. If I do it off the car is the sensor wire connected to power or ground via the resistor ?
Thanks again Vasek.
Re: What's up with the cam sensor...
Something like this :
- Attachments
-
- HALL.PNG (4.92 KiB) Viewed 3075 times
Re: What's up with the cam sensor...
One of my favourite garage customers stripped of some parts and pulled the cam sensor which was a complete nightmare. Despite what the new owner had been told it was the original sensor! It also seemed to be very loose in it's holder and a bit far out.
Replaced with a new sensor that the garage had sensibly ordered ahead and with the unit properly secured at the right air gap I get a completely different pattern !
- In fact exactly like the one you posted ! I would never have suspected such a regular pattern from a bad gap/bad sensor.
Thanks for your help, really appreciate it.
Replaced with a new sensor that the garage had sensibly ordered ahead and with the unit properly secured at the right air gap I get a completely different pattern !
Thanks for your help, really appreciate it.