Mazda 2 1.4 CR piezo injector trace

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Mazda 2 1.4 CR piezo injector trace

Postby gtop1342 » Wed Apr 27, 2016 7:42 pm

Hey folks
Anyone fancy a crack at this injector trace, i'm trying to figure out if the fault is in the ECM - wiring - injector..... the bad signal is on frame 3 of the file..... This is a very intermittent fault and took me nearly 2 hours to capture it. As you can see all was well before and after the fault...... Any advice will be very welcome because I always struggle with the cause & effect side of scope diagnostics.
Mazda 2
1.4D common rail unit
siemens injectors
Mazda_2_2008_Diesel_Injector voltage v current.psdata
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Re: Mazda 2 1.4 CR piezo injector trace

Postby ecosse » Wed Apr 27, 2016 9:02 pm

Whats fault with the car?
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Re: Mazda 2 1.4 CR piezo injector trace

Postby STC » Sat Apr 30, 2016 7:39 pm


I too would like to know what the fault is

You say this has Piezo Injectors, a quick Look a AD Online confirms that. However, on your trace I see Injector Voltage peaking at 9v. Something not quite right there ?? I'm thinking that's a set up issue, are you using an attenuator ??

Because all is well before and after the glitch for hours I'm thinking that the driver possibly may not notice the fault, Is it throwing a fault code and illuminating the Engine Light ?? Do you have fault codes ? What are they ?

Answers to the above questions would be a great help to fill the gaps.

Based on what I have seen I would, for now, Guess at Injector Piezo Stack Shorting to Earth internally, Possibly Wiring, then ECU needing a re Flow in that order.

If that was in front of me I would be doing an Insulation / Capacitance test to Injector Body / Ground on the injector & wiring using a Bosch FSA 050 or Megger MIT 420 / 480 tester shooting up to 200v (recommended is 100v) into it.

The Alternative is to swap that injector with another to see if the fault moves. Then you will know if it is the Injector or Wiring / ECU.

Granted, if it takes 2 hours plus to see the fault then you will be working for Love not Money. :D
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Re: Mazda 2 1.4 CR piezo injector trace

Postby KimAndersen » Sun May 01, 2016 7:49 am

I couldn't agree more.

There are definitely something wrong with the voltage signal from this piezo injector !!!. The voltage should be between 80 -150 volt DC and you are measuring around 10 volts - it doesn't seem right.

How did you measure this injector signal !!!.

When I look at your waveform capture over of the current path it looks right, with a peak value at 8.7 amps which is within the specifications.

As this Mazda 2 is equipped with siemens piezo injectors is the resistance value across the injector terminal pins different from a solenoid injector.

Siemens piezo injector have a resistance value at 150 to 250 kilo OHM.

It is also possible to make capacitance test.

This test is carried out by connecting the multi-meter in the same way as during the resistance check,
except the capacitance test is selected on the multi-meter.

Result: The capacitance should generally be between 6µF and 8µF.

We need some answers from you in order to help you ? :wink:

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