Lets discuss GDI Injectors

Matt Technician De Soto, Missouri Posted   Latest   Edited  
Discussion
Driveability
2017 Ford Edge SEL 2.0L (9) 6-spd (6F)
P0302 - Cylinder 2 Misfire Detected
Misfire
2.0

I'm diagnosing a Cylinder 2 misfire on this Edge this morning. And I check the COP and Current ramp the Injector. It's the first time I've done a current ramp on a GDI injector. It's a very different looking current ramp than I am used to seeing. Anyone wish to discuss what I am seeing? I'm curious why these are so different looking than other injectors.

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Jeff Diagnostician
Cathedral City, California
Jeff
 

It takes alot of amperage to overcome the fuel psi and open the injector, in yours it looks to be about 11 amps , once opened then about 3 amps to keep it open.

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Richard Instructor
Palmetto, Florida
Richard
 

Like Jeff has said, it takes a lot of current to get those injectors open and opened quickly. If you scoped voltage, you would see about 55-65 volts for that initial spike in current of 10-11 amps, then voltage falls back to 12V and amperage is 3 amps to hold injector open Until pcm turns off both power and ground to that injector. Most GDI injectors are wired in pairs for supply voltage and

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Chris Diagnostician
Commack, New York
Chris
 

Man, I was going to write up this whole concise description of operation and theory, but you nailed it.

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Matt Technician
De Soto, Missouri
Matt
 

The wiring on these shows they are wired each with their own set of wires from the PCM. Now what is inside the PCM I don't know.

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Ray Diagnostician
North York, Ontario
Ray
 

This is a GIF from the PSD file. Is the misfire fixed?

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Matt Technician
De Soto, Missouri
Matt
 

The misfire had nothing to do with either injector nor COP. The issue is actually a base mechanical issue with coolant getting into the cylinder overnight and misfiring first thing in the morning. It's got a bad spot on the block and head not allowing the gasket to seal between them.

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Caleb Technician
Mishawaka, Indiana
Caleb
   

This looks normal to me. Just scoped injectors on a 2016 Edge 2.0 Ecopoop the other day identical waveforms. However I can't read these waveforms well enough yet to know if it's actually flowing anything or not. But I can say by looking at this that the wiring and the PCM driver for the 65 volts an 12 volts is good. Also the scan tool has an injector balance test. I've had really good success

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Caleb Technician
Mishawaka, Indiana
Caleb
 

Oops just saw you found the same problem lol........

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Caleb Technician
Mishawaka, Indiana
Caleb
 

Also since we are on this topic is there a way to see a pintle hump on these waveforms?? If like too learn.

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Ray Diagnostician
North York, Ontario
Ray
   

We will not see any "pintle hump" because the GDI injectors do not use the traditional pintles. They use a stack of silicon chips to open the pintle valve. Each chip expands a few thousandths of an inch when exposed to an electric current, which allows fuel to be injected in rapid bursts during each injection cycle. This feature allows the PCM to "shape" the burn cycle

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Phillip Diagnostician
Anchorage, Alaska
Phillip
 

is this why you see the multiple current spikes after the initial spike?

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Richard Instructor
Palmetto, Florida
Richard
 

This particular vehicle and most domestic vehicles that I have seen do not usually use a piezo style injector. But even a conventional coil solenoid style GDI injector will not show a pintle hump because of the speed of operation. The current spikes after the initial high spike is the pcm rapidly swithing the 12 volt driver on/off to control current. I attached a scope capture of a 2014 Ford

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Scott Manager
Claremont, California
Scott
 

Hi Caleb, This discussion might be of interest:

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Caleb Technician
Mishawaka, Indiana
Caleb
 

Thanks for all the excellent info guys.....i will read it by an by!

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