Motor Age How2 #15 - Exploring Fuel Injector Waveforms

[@ninjatechauto655]

Thank you so much. Finally I found a channel that actually explains why it looks like that in detail.

[@selvamg635]

You well explained of the pintle open and close to check using voltage and current pattern. Thanks for your teaching well to understand.

[@fomocotech]

Thank you for taking the time to make these videos

[@1b9e7n3z]

As always very technical, useful and professional, thank you for sharing all this knowledge

[@robertjohnson4401]

What make and model of scope did you use for these waveforms? The challenge with lower end scopes is seeing the pintle opening, especially on the voltage waveform. To see the pintle opening on the voltage waveform, expand the voltage at the bottom of voltage waveform when the ECM commands the injector open and see the bump. Lower end scopes do not have the resolution to see this opening bump.

[@ahfelgazzar]

Very brief yet very rich information 👏👏

[@kellyr9388]

great job Pete.

[@IsshmanGarcia]

Thanks Pete good information as usual.

[@ThunderbirdRocket]

Fantastic ! Thanks !

[@jahrain1693]

Good and informative

[@markkuba5074]

Exactly what I need.

[@tboneproductions2453]

Great explanation. Thank you

Nice stuff

[@vincebauer4777]

So I think a low amp clamp is your best way to check injectors is that what u are getting at ???? if a guy can get at the wires

[@MotorAgeMagazine]

Not necessarily the "best" way, but A way for sure. I believe in having multiple ways to test any system - and then use the test best suited to the situation.

[@blackbambinoe]

Loves the break down of scope logic. Thanks again

[@josephtucci3666]

Well done as all ways sir. Mabey a bit moor on shorted and open injectors just saying

[@perez7667]

Hey, Pete.Could you please explain to us what an injector waveform would look like if an injector winding were open? I have a hard time picturing it. I know that there won't be any magnetic field, no ON- time; therefore, no voltage spike. But, will the 12v only be pulled to ground?

[@SouthernBikerTV]

If the windings or the circuit were open, you'd see 0v on the waveform. Just like a voltage drop test...

[@ronaldamodeo4567]

Pete didn't some early Mopars fuel injection systems not pull a full 12 volts when switched on but only pulled 10 volts? I am trying to remember I have not worked on one in years but it was the norm to only see it pull 10 volts when switching on leaving 2 volts behind and that could lead you down the wrong path. If memory is correct...

[@MotorAgeMagazine]

Sorry, don't recall...that may be, though, especially on early designs. That's why I always say you need to know the system you are working on to know what to expect on your screen.

[@keitheaton7562]

Where do we look for high current across the coil. Is this a thing?

[@MotorAgeMagazine]

High current would be caused by a shorted coil. I like to place my amp probe at the fuse feeding all of the injectors to check for this. The bad one will stand out from the rest. I've also restarted this series - you may be interested in following along!

[@electronmarkboggess63]

Great job!!! Would it be possible to do a Video explaining floating grounds? I think it would be good for those who don't know what it is

[@MotorAgeMagazine]

Mark Boggess Sounds like a great idea!

[@electronmarkboggess63]

Yes like for example today I was playing with my scope and scoping the O2 sensors on my personal car. I noticed that the Vmax was 1.7 volts of my No1 sensor and it was switching but seemed to be floating off my Zero point on my scope.. I was on the Battery ground not the sensor ground..now is that because it's a floating ground that's already at so many Mili volts above true chassis ground??

[@MotorAgeMagazine]

Mark Boggess Yes. And true of any sensor that grounds to the ECM.

[@electronmarkboggess63]

awesome thanks for the replay I had a idea that was the case but in the back of my head i was doubting my scope as I was always streaming the PIDs via the BlueDriver scan tool and seen it was within the normal O2 sensor range.. I was ready yo throw my cheap Hantek away as I felt I could not trust it but thought " duh I'm sure it's because I'm on battery ground and sensor ground is just a small milivolt positive potential" lol Once again thanks for the replay and thank you for all the awesome videos for us self taught guys it helps a whole lot !!!

[@MotorAgeMagazine]

Mark Boggess Your welcome!

[@Gmansour1971]

Wow, I just realized that I'm looking at an OPENING pintle hump in the amperage wave form, and a CLOSING pintle hump in the voltage wave form??? Is that correct?

[@MotorAgeMagazine]

Yes!

[@Gmansour1971]

@@MotorAgeMagazine awesome, thank you!

[@cubenitup]

So is the voltage pattern theoretically supposed to be flipped upside down on the graph?

[@MotorAgeMagazine]

Not sure I understand your question. Can you reference it to the time stamp on the video, or clarify what you're asking?

[@cubenitup]

@@MotorAgeMagazine so on the voltage pattern on the injector of the graph, when it’s grounded getting power the graph shows it going down and then the ecm “ungrounds” the injector showing it “turn off” and then it spikes. Wouldnt that entire graph supposed to be flipped upside down on the graph?

[@cubenitup]

@@MotorAgeMagazine oooh never mind. Because the injector is getting power 12-14volts all the time. I understand nvm

[@MotorAgeMagazine]

​@@cubenitup Remember where we are connected. When our measuring lead (positive lead) is placed on the ground side of any electrical load, it should read Open Circuit Voltage when the circuit is off and when the circuit is turned on, the voltage should drop across the load and read near "0". In the case of any device that uses a magnetic field, this is also the time period that the field is being energized. When the power to the coil is removed, the magnetic field collapses and creates the voltage spike you see. Make sense?

[@cubenitup]

@@MotorAgeMagazine yes awesome!!

[@billyr9840]

Nice !

[@tgoodm1]

👌👌👌

[@anthonynicholls8010]

😎✌️