Diesel Retour Flow Sensor?

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Diesel Retour Flow Sensor?

Postby macfarad » Wed Aug 17, 2011 11:13 am

I'm very charmed by the Diesel Retour Flow Sensor that is sold by the Dutch organisation GMTO.

It measures retour flow of 4 different diesel injectors in order to diagnose injector wear or problems. It is very handy in case of piezo injectors (with pressurized retoursystems). The amount of fuel that passes through the sensor is displayed by GMTO's PC-scope.

Unfortunately I can't use it with the PicoScope, since the software needs specific algorithms to display the correct waveforms.

This system is very clean solution to measure the exact amount of retour fuel, even on the road, without having the entire engine bay covered in diesel fuel.

I was wondering if Pico had any short-term plans to develop a system with similar capabilities. I think it would be very popular.
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Re: Diesel Retour Flow Sensor?

Postby Alan » Wed Aug 24, 2011 8:41 am

Hi,

I expect the GMTO unit is made using flow meters that give a pulse output. As we can measure the frequency of such pulses using maths channels in PicoScope it may well be possible to use this unit with our scopes.

For nearly all injectors its possible to use low cost kits like this one http://www.toolbox.co.uk/sealey-vs2046- ... 922-109391 Is measuring the flow onto the PC worth the extra money? If there is a good reason and demand we will look further into this.
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Re: Diesel Retour Flow Sensor?

Postby macfarad » Wed Aug 24, 2011 9:30 am

I'm aware of the lowcost kits kits and I use these kits myself, but measuring the return-flow with a scope has many advantages:

  • Using a GMTO-like system allows a test on the road, with accelerations and at high speeds. Dynamic testing with a lowcost kit is almost impossible, because the cups have to be placed somewhere in the engine bay while driving, the are filled up to fast, diesel fuel gets spilled, etc ...
  • The most important advantage is that the system is placed in line with the return-flow system. Common-rail piezo injectors need a pressure in the return-flow system of up to 10 bar. This makes it impossible to do a correct test, with the traditional cups.

With a return-flow sensor the fuelsystem remains closed so the injectors are not influenced by the measurement itself. There are already a lot of diesel-engines out there in Europe with piezo injectors, and if we can't measure the return-flow correctly, in my opinion, we lose an important step in diagnosing common-rail systems.
But even for the traditional common-rail systems, it's big improvement over the low cost kits.

Given the growing marketshare of diesel engines in Europe, combined with the increasing use of bio-fuels, chances are we are facing a lot of injector-problems over the next few years. With these points in mind, an efficient test-kit is no luxury.

I would expect that if Pico sells such a kit, it would be a success.
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Re: Diesel Retour Flow Sensor?

Postby macfarad » Wed Aug 24, 2011 10:50 am

In this YouTube-video you can see the system in action:

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Re: Diesel Retour Flow Sensor?

Postby Alan » Tue Sep 13, 2011 10:31 am

Hi,

Sorry to take a while to reply, but to be honest I am not that familiar with return flow testing and every time I thought to ask someone else here they were on holiday.

You mention a couple of advantages of using this technique over the low cost kits:

1. Testing under load. I can see the advantage of this, but the correct way to do this is to command the high pressure pump to full pressure either via the diagnostic tool or an adaptor so a road test is not required. I accept that this method is more of an option for a main dealer / diesel specialist than for the aftermarket.

2. Systems that require pressure in the return flow. My colleagues inform me that some Denso systems are pressurised in this way, but there is no access to the individual injector return flow so this technique will not work. What common makes / models with pressurised return flow have access to the individual injector to measure the flow?

Sorry if my questions / comments come from a lack of knowledge here, but I am trying to see if there is a market for this device.
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Re: Diesel Retour Flow Sensor?

Postby 924marc » Thu Sep 22, 2011 12:11 pm

I'm using that kit from GMTO with my pico.

The only difference is that I can't see how much fuel (volume) is deliverd by each injector, because that's what the software from GMTO calculates.
But what I see is the relationship between the injectors and in the meantime a scanner where we can see the adaptations that are made by the ECU. This gives you a verry good idea of the system.
It's like Macfarad allready sad ,now we can perform a dynamic test on the road where the injectors are working under load.

Below you can find a test from a Mercedes Benz 200CDI with 2 new injectors on cil 2&4, during a test drive.
The setup from the channels is
A:cil1
B:cil2
C:cil3
D:cil4

Kind regards
Marc
Attachments
2&4 vv retourflow dynamisch.psdata
(1.59 MiB) Downloaded 420 times
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Re: Diesel Retour Flow Sensor?

Postby hbr » Mon Nov 21, 2011 9:32 pm

Any news on this subject? Is pico building something like this?
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