Common rail diesel - piezo injector: current

The purpose of this test is to check the current for a piezo diesel injector under different operating conditions.

Connection guidance

Connection for diagnostic work will vary dependent on application.

Technicians should whenever possible gain access to the test circuit without damage to seals and insulation. If this is not possible then make sure appropriate repairs are completed.

General connection advice

PicoScope offers a range of options within the test kits.

Dependent on difficulty of access, choose from:

  1. Breakout leads.
  2. Back-pinning probes.

Testing sensors and actuators (to include relevant circuit/connectors):

  • When testing a sensor, it is desirable to gain access at the control module.
  • When testing an actuator, it is desirable to gain access at the actuator.

How to perform the test

  1. It may be necessary to carefully strip back the loom outer insulation to access the injector cables. Repair the loom insulation once the tests are completed.
     
  2. Plug the low amp current clamp into PicoScope Channel A. Set the clamp to the 20 amp setting and zero the clamp before connecting to the vehicle.
     
  3. Start the engine and allow it to idle.
     
  4. Minimise the help page and with the example waveform on your screen PicoScope has already selected suitable scales for you to capture your waveform.
     
  5. Select GO or press the spacebar to see live data.

Note: This waveform has been set up in Auto trigger mode, with a rising-edge trigger. If the waveform does not start with a positive pulse, the current clamp has been connected the wrong way round. Remove it and replace facing the opposite direction.

Waveform notes

These example waveforms show the injector current during different operating conditions. 

The positive signals are the injector open commands and the negative signals are the injector close commands. Therefore the time between the positive peak and the negative peak is the injector on time controlled by the Engine Control Module (ECM).

Example 1: The first two injector phases are pre-injection and the third is the main injector phase.

Example 2: As the engine speed is raised the ECM increases the duration of the main injector phase.

Example 3: On over-run only the first pilot injection phase remains.

Waveform Library

Go to the drop-down menu bar at the lower left corner of the Waveform Library window and select 'injector current'.

Further guidance

Piezo injectors have the advantage over conventional electromagnetic injectors of a very quick reaction time up to four times faster.

Piezo injectors operate using of a stack of about 300 thin piezo ceramic plates. When the switching voltage is applied the plates expand opening the needle and allowing pressurised fuel into the cylinder.

As with all common-rail systems, there may be various injection phases.

  • Pre-injection or pilot phases are to combat diesel knock by gently starting combustion.
  • Main injection phase is for the power and torque characteristics.
  • Post-injection is to increase combustion temperature during diesel particulate regeneration.

Figure 3 shows a piezo element in its two different states. Illustration 1 shows the stack with no supply voltage and illustration 2 shows the increase in height of the stack when the supply voltage is switched on.

Note: Once the stack is in the injector open position it does not need to have a continuous supply voltage and will remain in the open state until the close command. For this reason never disconnect the injector multi-plug with the engine running. If the injector is in the open state it could hydraulic lock the engine with diesel fuel.

The engine will cut out if the control module detects any faults with the injectors or driver circuit.

Diagnostic trouble codes

Selection of component-related Diagnostic Trouble Codes (DTCs):

U0105 Lost Communication With Fuel Injector Control Module

U0306 Software Incompatibility with Fuel Injector Control Module

U0406 Invalid Data Received From Fuel Injector Control Module

P0200 - Injector Control Circuit

P0201 - Injector 1 Control Circuit

P0202 - Injector 2 Control Circuit

P0203 - Injector 3 Control Circuit

P0204 - Injector 4 Control Circuit

P0205 - Injector 5 Control Circuit

P0206 - Injector 6 Control Circuit

P0207 - Injector 7 Control Circuit

P0208 - Injector 8 Control Circuit

P0209 - Injector 9 Control Circuit

P0210 - Injector 10 Control Circuit

P0211 - Injector 11 Control Circuit

P0212 - Injector 12 Control Circuit

P0261 - Cylinder 1 Injector Circuit Low

P0262 - Cylinder 1 Injector Circuit High

P0264 - Cylinder 2 Injector Circuit Low

P0265 - Cylinder 2 Injector Circuit High

P0267 - Cylinder 3 Injector Circuit Low

P0268 - Cylinder 3 Injector Circuit High

P0270 - Cylinder 4 Injector Circuit Low

P0271 - Cylinder 4 Injector Circuit High

P0273 - Cylinder 5 Injector Circuit Low

P0274 - Cylinder 5 Injector Circuit High

P0276 - Cylinder 6 Injector Circuit Low

P0277 - Cylinder 6 Injector Circuit High

P0279 - Cylinder 7 Injector Circuit Low

P0280 - Cylinder 7 Injector Circuit High

P0282 - Cylinder 8 Injector Circuit Low

P0283 - Cylinder 8 Injector Circuit High

P0285 - Cylinder 9 Injector Circuit Low

P0286 - Cylinder 9 Injector Circuit High

P0288 - Cylinder 10 Injector Circuit Low

P0289 - Cylinder 10 Injector Circuit High

P0291 - Cylinder 11 Injector Circuit Low

P0292 - Cylinder 11 Injector Circuit High

P0294 - Cylinder 12 Injector Circuit Low

P0295 - Cylinder 12 Injector Circuit High

GT098-4

Disclaimer
This help topic is subject to changes without notification. The information within is carefully checked and considered to be correct. This information is an example of our investigations and findings and is not a definitive procedure. Pico Technology accepts no responsibility for inaccuracies. Each vehicle may be different and require unique test settings.

Suitable accessories

  • 30 A (low amps) current clamp

    £259.00

  • 20 A / 60 A DC (low amps) current clamp

    £111.00

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1 comment | Add comment

Khir
March 07 2017

2007 Astra diesel won’t start after turning off the engine
Then engine just start by tow another vehicle and I’d not how to check injectors power and the fuel is ok from pump.

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Guided test: Common rail diesel - piezo injector: current