I checked quite a lot of things today
I checked O2 sensor voltage when the engine was hot and running, at idle the voltage doesn't change, 0.07V, but on throttle it goes from this value to 0.90V.
I tried to start without the fuel tank cap, no change.
I back washed the injector, clean petrol came out.
I measured fuel pressure : 2.9 bars. Should be 3 but my measuring device is a cheap one, so it could be 3 !
I took the fuel pump out to inspect, I have no clue if the filter is supposed to look like this
The tank looks clean
The fuel pump o-ring that seals in between the pump and the tank was very loose, I put it back cause I didn't have any spare but I will replace it asap.
I tried to start with the air box disconnected, no change, it starts, but hardly, as usual.
I unplugged almost everything I could see, no sign of corrosion into plugs.
I checked ECU relay, clean. I swapped it with low beam relay, no change.
I couldn't try to swap it with the 300 because I have to dismantle many body parts on both machines and I didn't have enough time to do so.
All air lines seemed normal, the throttle body is firmly in place, maybe I should take the throttle body manifold off to inspect ? It looks really sturdy, I don't see why the gasket would let air go into, otherwise it would be rough even after start, no?
I spend to much time on that "thing"