Hose from beside the windscreen wiper

[egilkv]

There is a hose coming out from the firewall, beside the windscreen wiper, that on my car isn't connected to anything. Can't find anything obvious it should be connected to (the fuel pressure regulator vent should stay open, right?) Can anyone help shed light on this, please?

[TwinKam]

It's for the manifold air pressure sensor, should be a hole in the airbox for it.

Edited by TwinKam on Thursday 1st July 09:13

[egilkv]

So it is, and I actually should have remembered. Thanks a lot. I've labelled it now, so I'm fine next time.

[Stunned Monkey]

it's a GNDN. The ECU does nothing with this input.

[egilkv]

Interesting that manifold pressure is not used. Then the mapping must be based entirely on RPM and throttle position, in addition to lambda feedback?

[Imran999]

Yes, the ECU has no idea of airflow at all, it’s a barely closed loop closed loop control system.
The lambda’s only report whether the air fuel ratio is at stoichiometric or not, and the ECU uses this information to richen or weaken the mixture (by adjusting injector duty cycle).
Crude, but effective and seemingly quite reliable.
IMO, modern cars are needlessly complex, I really appreciate the simplicity of cars from the late 1990’s, when they had enough technology to achieve high levels of performance and reliability, but not so much, that maintenance became a nightmare and relatability eventually suffered.