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While I was doing a virtual compression test on my friends 2010 Peugeot Partner II 1.6 Turbo Diesel I hooked a probe up to an injector so I would have a reference point to know which cylinder is which during the virtual compression test. What I got was the injector firing on every turn of the engine.

So is it a common thing for diesel injectors to group fire during cranking, if that's in fact what I'm seeing here?

EDIT These are voltage readings... I'm using a 20:1 attenuation on the injector and a 10 kilohertz low pass filter...

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EDIT I went back and retested with three of the four injectors disconnected and I still got basically the same thing. I'm wondering if maybe this is a result of a fried ECU... The replacement EGR apparently fried the diode for the solenoid control and I'm wondering if this is somehow connected to that...

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  • Is thus only during cranking or also when the engine is "running" stable?
    – Martin
    Mar 14, 2021 at 16:02
  • @Martin Not sure, this is a no start. One thing I am seeing is that everyone seems to use an amp clamp when testing diesel injectors, not voltage... Not sure why that is...
    – Robert S. Barnes
    Mar 14, 2021 at 17:55

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I don't know for certain, but I would think no compression ignition (CI) engine should batch fire injectors. The reason is how the CI engines work. You don't want fuel in the air which is being compressed, or it could spontaneously combust at any time. You want the combustion to happen at exactly the right time, akin to spark timing in a spark ignition engine. If you batch fired, there would be fuel in the intake charge, which means it could burn at any time the temperature got hot enough to burn. For this reason, I'd say it is nearly impossible for a CI engine to be batch fired.

As far as what you're observing ... are you positive it's not a 2-stroke engine? I don't think it's a common way for diesel engines to operate, but I do know they exist (Detroit Diesel 71 series engines were 2-stroke engines). A 2-stroke engine would fire during every revolution. If it is indeed a 4-stroke (most likely), then there's probably a problem in the injection system.

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You mentioned this was without ignition, or at least it sounds like it. Since it isn't actually igniting, maybe the PCM wants to do a power stroke on every TDC?

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