how to test a mosfet with digital multimeter on an N43 engined 3 series that had a persistent misfire that a new coil, spark plug and fuel injector fitted by a previous garage DID NOT cure the fault.
In this video from about 6 years ago I cover with the Pico scope what the waveform of a piezo injector is supposed to look like then I show the damaged waveform.
I also cover in depth mosfet testing which will enable you to accurately diagnose whether you have a failed mosfet transistor.
This video could save you alot of money by learning how to diagnose it. YOu then have the options of learning from other videos how to upgrade your transistors or just replace the failed one(s).
Disclaimer - This video is purely information only. I am not responsible for anything that you do. If in doubt please entrust your car to a qualified professional.
-------------Contents------------------------------------------------------------------------------------------------------------------------------------
00:00 Introduction
00:28 Discussing the pico scope setup
00:55 Looking at a still image of a piezo injector waveform from a known good cylinder (voltage versus current)
01:29 Scope trace view of the good cylinder piezo injector scope traces (current and voltage)
02:31 Scope trace view of the non running cylinder (current and voltage)
02:47 Opened up the MSD-80 DME and explanation of the mosfet source, drain and gate
03:04 Testing a known good mosfet then a faulty mosfet
