Piezo and solenoid injector operation?

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TanScan
Newbie
Posts: 3
Joined: Fri Sep 04, 2020 3:11 am

Piezo and solenoid injector operation?

Post by TanScan »

Hi There

I'm looking to learn more about piezo injectors and solenoid injectors on direct injection engines.
I've read up and seen on videos that the piezo injectors are controlled from both wires by the ECM but I was wondering what is actually happening and how are these being controlled? ie: how are they switched/grounded to change current flow?

Another video I've seen is someone testing the ground of a piezo injector by putting a test light to the casing as the engine was running. Is someone able to explain this to me? Are they controlled by 2 wires as well as grounded from the casing?

I was also looking at solenoid type injectors in direct injection vehicles such as common rail diesels. Are these similar to standard petrol injectors which are negatively switched with a pulse from the ECM? or do they have a different operation as well?

I'm grateful for any answers or any leads to where I can find these answers.

Thanks for your help

Steve Smith
Pico Staff Member
Pico Staff Member
Posts: 894
Joined: Sun Aug 25, 2013 7:22 am

Re: Piezo and solenoid injector operation?

Post by Steve Smith »

Hello and thank you for the post
For information on Piezo injectors, this forum post will most certainly help topic19561.html

You are correct that Piezo and a number of Solenoid injectors are fired using finite control of both the power and the ground wires. (Once again, the link above is worthy of a read)

These injectors do not ground via their body to the cylinder head, in such a scenario we have an insulation fault and so error codes, misfire & non start symptoms

Our Guided Tests will help you here too as we have a number of Diesel injectors covered along with “More Information” to assist with the theory of operation.

This one will help you with PD Solenoid injectors as we have power, ground and current covered https://www.picoauto.com/library/automo ... and-earth/

Please be aware of the voltages involved with these injectors, especially Piezo which can exceed 200 V and so attenuation is required with all our automotive scopes.

As an exercise to help bring the theory to life, place a current clamp around one of the wires of your injector, add attenuators to 2 x test leads and probe the wires either side of your chosen injector (Referenced to ground) as with the PD injector test above

Once you have the capture, look at the relationship between the current flow and voltages in both your measured injector cables.

Remember: for current to flow, there must be a voltage differential between these injector wires, this will reveal how they are switched and so operate

I hope this helps, take care…..Steve

TanScan
Newbie
Posts: 3
Joined: Fri Sep 04, 2020 3:11 am

Re: Piezo and solenoid injector operation?

Post by TanScan »

Thanks mate for the help

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