Waveforms related to the DPF Load and temperature Sensors

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Waveforms related to the DPF Load and temperature Sensors

Postby Experimenteer » Tue Jul 20, 2010 8:31 pm

Would be very interested to read about anyone's experiences with probing DPF load sensors, associated temp sensors etc.
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Re: Waveforms related to the DPF Load and temperature Sensor

Postby Experimenteer » Tue Jul 27, 2010 6:18 pm

Has nobody gone near a DPF with a scope?

Anybody know if the load and exhaust temps sensor signals are basic 5v like a map sensor?

Or digital or differential outputs?
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Re: Waveforms related to the DPF Load and temperature Sensor

Postby Dave Hill » Tue Jul 27, 2010 9:05 pm

Hello Expeerminter (Can I have your name please? :wink: )

I have some waveforms from a differential pressure sensor, that I captured, whilst applying a vacuum & then pressure. I have never bothered capturing the signal from the temperature sensors though. They don't seem to give any problems.

I find it more convenient to study the pressure readings vie serial data. By observing the pressure reading at "key on engine off" & then running the engine at a variety of speeds, it is possible to determine if the sensor is functioning correctly & furthermore, if the DPF is clogged, partially clogged, or even clear. Some back pressure is necessary, otherwise a DTC will be set for "Particulate filter punctured"

HTH

Dave
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Re: Waveforms related to the DPF Load and temperature Sensor

Postby Experimenteer » Wed Jul 28, 2010 9:26 am

Names Tony.

Would it be possible please to get a look at those waveforms,
or at least a written description such as + or - 5V or whatever?

Where are you reading the serial data from?
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Re: Waveforms related to the DPF Load and temperature Sensor

Postby Dave Hill » Sat Jul 31, 2010 3:10 pm

Hi Tony

Most good diagnostic tools can display "differential pressure sensor" parameters. I use Peugeot Planet, but I have seen the same data on other tools too.

I can't lay my hands on the waveforms at the moment (I have misplaced my USB 500GB portable drive :cry: )

From memory the waveforms were fairly unexciting & you shouldn't have any problem in finding a donor car, so that you take some good reference captures from.

I will look out for my captures & post them when I get time.

Cheers

Dave
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Re: Waveforms related to the DPF Load and temperature Sensor

Postby Experimenteer » Tue Aug 03, 2010 5:09 pm

Hi,

Due to rather long winded internal funding and requsitioning processes, I will not have a scope
to play around with for about 8 weeks.

I would be most grateful if you could describe the typical DPF signal.

For example, is it 2.5 V downto zero when pressure is applied in one direction, 2.5 upto 5 when applied the other way - in other words differential outputs like would be fed into a single supply op amp?

Or is it simply vehicle ground to 5 V, with a 5V supply to the sensor? Is it two wire only? Is it relative to vehicle ground or a floating situation?

Thanx,

Exp
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