Trying to get access to my heater pump, I started wondering what part number 4 does.
I think I understand the basic principal of operation of the hot wire air flow meter, but can only guess what the box is for.
Maybe someone who knows can explain.
Cheers,
Harald
From what I understand it’s an expansion chamber in the event of a back fire it allows the hot wire to not get damaged?
IIRC that is it Robin, it wasn’t much of an issue on any of my X300s as no backfires with prolonged cranking after stalling but on X308s they were known to get destroyed if a backfire happened after washdown caused by turning off the engine before fully warming up.
Interesting. I would have thought it would need to be a lot bigger to help with backfiring…
Thankfully I never had it happen but some reported blowing up the Airbox on their X308s.
The wire of course is heated and the current measured, the air mass cools the wire and changes its resistance. I have never seen such a box in that location, but ahead of the AFM they are sometimes parts of the intake designed to act as resonance chambers. Either to tune the sound or maybe to smoothen the signal. Backfire protection: can’t see how, and why no other car I know has it? My guess is that they had some unwanted dynamic that upset the hot wire and this was the fix.
Thanks! I will read through this!
Cheers,
Harald