Injector leak off test results

The description sounds like injector three is plugged or the coil is shorted so it isn't moving the pintle off the seat. Injector 4 on the other hand is flowing in excess. If you have a volt/ohm meter you can use it to test the coil in the number three injector. Set it to ohms and test it, then compare that number to the other three injectors. Say you test number 1 and find 2 ohms resistance, then number 2 shows 2.1 ohms but when you test number three it reads infinity (open circuit) you know the injector is open circuit. Now say you test number 4 and find it reads .75 ohm. That would be an internally shorted coil. The control system is designed around somewhat fixed numbers. They determine the flow rate by pulsing the current to the injectors on/off. If the resistance in a coil is different than what the system expects you get the wrong flow rate.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Overall I would say a set of replacement injectors would be a good idea, that way they are matched for flow rate and you don't have many cylinder to cylinder power variations.

Hi KING HADI SOUMARE,

In your post you do not specify any codes or check engine light on. Also is it 1.5l diesel or 1.6l gasoline? I would second the injector having a issue.

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Nick

Okay, when you do a flow return test in each injector look to see how much is it dripping or is there more of a flow if there is a more of a drip the injector is leaking. Also did you have black smoke when you raise idle at the exhaust?
Also drain your fuel filter in a clear clean container to see if there is metal shavings.
This sounds like you have.9 to 1.0 injectors are dripping more than they should. Look to see if there is black smoke at the exhaust, if there is smoke find the injector that drips' more and replace it. And re do test flow return, if you metal shaving. There is failure at the injection pump.
Cheers, Nick

You have to drain your fuel filter at the pump to see if meatal shavings.
as for #4 has to much return, this one should be replaced, what you need from the returns is minimum fuel, black smoke is rich fuel in getting in to the combustion, possible dripping injector. you have to make a decision on replacing one at a time or replace all injectors,
Remember to wright down the number of the injector for each cyl and wright down the new part number you might have to program (https://youtu.be/s1bL2McGa0Q)
Cheers, Nick

Not even a drip? If no drip at all it could be clogged.
On ohms testing I can remember the specification, take a reading on all and if your average is about 1.2 to 1.5 you should be okay. You also have to replace one you can take a reading of the new or refurbished one.
Cheers, Nick