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Quick Tip: Piezo Injectors Signature Test

Applies To: MODIS Edge™, MODIS Ultra™, VANTAGE® Ultra, VERUS® Edge, VERUS® PRO, ZEUS®

Vehicle: 2016 Ford Escape. Did you know that the fuel injectors on Direct Injection vehicles work differently than a standard fuel injector? Because of this, a lab scope pattern may not look like what you may be used to. In this Diagnostic Quick Tip, National Field Trainer Jason Gabrenas shows you how to hook up and perform a signature test on a Ford EcoBoost® motor.



A lot of newer cars use gasoline direct injection. It's a far more efficient way of injecting fuel into the engine.

They had had been using it on diesel vehicles for quite some time but it's kind of new on the gas side of things, so if you've never worked on a diesel you might not know it's a little bit different.

I'm going to walk you through it on this tool right here. We have got a lot of information on how those injectors work and it's actually hooked up to this Ford behind me and we can see how it looks on a lab scope and how the pattern is actually different than a standard fuel injector.

Inside all the lab scope tools is the Guided Component Tests and that can give us a lot of information on how things work and where to hook up on these vehicles.

We have the vehicle ID here so we're going to go into the Fuel Injection System and then we're going to go into the Fuel System, and then the Fuel Injector. Now it's going to give us some information so we'll go into Component Information and it says how the system operates:

  • The gasoline direct fuel injector delivers fuel directly into the cylinder under high pressure.
  • Each injector is controlled by two circuits from the PCM.
  • A boosted voltage supply up to 65 volts is generated in the PCM and used to initially open the injector.
  • The injector driver controls three transistors switches that apply the boost voltage to open the injector and then modulates the current to hold the injector open.
  • If boost voltage is unavailable, the correct injector opening current might not be generated in the time required.

It contains a smart driver that actually monitors each side to see whether there's a problem that will throw a code for whatever the problem happens to be.

It says the best place to test that is either at the injector itself on these, they're sometimes hard to get to or there's a 16 pin connector on the left rear side of the engine above the engine oil filter housing. That's where we've hooked this up.

So now that I've got all this information here, they don't actually have a test that we can test all three things.

We're going to go into the lab scope, which I already have set up running on this vehicle. And you can see here we have two different types of patterns displayed. So let me stop it on this second pattern here.

This would be powering up the fuel injector. You can see that we have a little voltage spike right there, and at the same time the spike goes up, we also have the amperage going up.

Then the amperage drops off slightly, and then it comes down and then as it says, it modulates the amperage up and down to keep the inject open.

As the amperage goes up and down, the voltage has to follow that as well. So that goes around.

And then when it's released, we're still going to get another spike into the injector back into the line, when it closes.

So you can see it's a little bit different, but as long as you know the theory, it'll help you diagnose it.

Last Updated: December 9, 2019

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