If possible I would like to point out a few points of interest which might be a nice topic to make a video on (if you come across issues on these)
One I struggled with for a bit before finding out a good route to success is the variable valve timing issue.
Lots of cars have cam shifter, actuated by solenoids. Especially which brands like VW FSI cars etc. we find loads of problems on chains (they call it extension of a chain, but more over it seems to be wear). Most likely you have an indication with a rattle on starting the car - this might however be the chain / tensioner, but also there might be a problem with the shifter. If you change the chain, you really want to know or the shifter should be changed as well (or you will be having a double time job on your hands plus explaining to the customer)
Would be great to have a good video on this topic. How to scope timing with disconnected actuator and why, what bad oil can do, etc.
--
other thing I found lately was a symptom that might throw one off as well. Got a car which ran horrible (idle) at times and threw a P0505 with the notification "high voltage"... Could be an open circuit in the idle circuit, in the wiring, in a harnass ? With an actuator test however the idler (external, pushing against the gas cable connector), worked fine at times (after erasing the codes). Then it fell to my attention it stopped at times while still 'humming'... the steps in the parameters on the tester showed it stopped as well. Turned out it's not the 'voltage' that is in issue, it seems an ECU may see amperage rising (on a motor actuator) and shows it as 'voltage high' ... that will throw you off.
