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Toyota echo engine Shutdown

hello everyone , i recently change the air filter and the pcv valve of the car myself , one thing i notice is that if the car is running (iddle) and i unplug the hose of the PCV valve on the manifold side the engine shutdows, why is this? is not the engine computer system supposed to compensate for such things?

thanks and regards

The hose from the PVC valve is directly attached the the intake manifold, and disconnecting it opens a large vacuum leak. It is working the way it is supposed to. The engine computer cannot completely compensate for such leaks. Your asking too much of it.

The engine computer takes into account a restricted amount of air through the pcv valve. Disconnection of the hose allows a lot of unmeasured (unmetered) air into the intake. This unknown amount of additional air throws a monkey wrench into the calculations.
The mass air flow (MAF) sensor measures (“meters”) the amount of air going into the intake, and tells the engine computer the amount----moment to moment. The engine computer uses that information, along with information from other sensor, to control the amount of fuel injected into the engine.

understood , the same thing happens when i unplug the hose from the pcv valve side while the engine was running , it shutdowns , so i tought that maybe the computer is not working anyway i guess is not ok to do so , i was just testing what happens if…

thanks a lot guys

The mass airflow sensor knows to cut off the fuel when there isn’t enough air going through the throttle body. It doesn’t want to cause a rich fuel mixture or flood the place with gasoline. It’s only a 1.5 engine which used to be about a third of an engine.