ISV
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Intermediate
Joined: Dec 2021
Posts: 46
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ISV
Sorry for writing i'm using the translator.
I would like to know the operation of the valve isv regulation system. Where it comes from and where the flow of passing gases goes? Some pattern. Thank you very much
I would like to know the operation of the valve isv regulation system. Where it comes from and where the flow of passing gases goes? Some pattern. Thank you very much
Drifting
Joined: Dec 2019
Posts: 2,617
Likes: 1,701
From: New Jersey
At idle, the valve position is opened, which allows air to bypass the throttle plate (which is closed because at idle you are not stepping on the accelerator, opening the plates). The air comes "from" the intake coupler, just after the air box and MAF, right before the throttle plate. The "to" returns the air behind the (closed) throttle plate. This again allows a small bit of air to enter the intake manifold, allowing the car to idle.
When you are not idling, the valve closes so that air cannot bypass the throttle plate, and instead air ratio into the manifold is controlled by the throttle position sensor (how much you are accelerating). The valve typically gets gummed up and gets stuck in the closed or partially closed position. So at idle, this leads to a stumble or lack of idle completely due to lack of air.
When you are not idling, the valve closes so that air cannot bypass the throttle plate, and instead air ratio into the manifold is controlled by the throttle position sensor (how much you are accelerating). The valve typically gets gummed up and gets stuck in the closed or partially closed position. So at idle, this leads to a stumble or lack of idle completely due to lack of air.
RL Community Team
Rennlist Member
Rennlist Member
Joined: Jul 2004
Posts: 10,597
Likes: 2,049
From: Dallas, TX
Hi Danie,
The idle air control valve is controlled by the Bosch Motronic ECU. The ECU keeps a check on the engine's idle speed. The ECU uses the Idle control Valve to control the amount of air that is allowed to bypass the throttle body supplying air to the intake manifold, so as to keep the engine idle speed constant.
Lots of articles on the internet explaining its function.
It is a service item on our cars that needs to be cleaned regularly. It can be tested. Here is a page on the subject:
https://993servicerepair.blogspot.co...r-robbing.html
Andy
The idle air control valve is controlled by the Bosch Motronic ECU. The ECU keeps a check on the engine's idle speed. The ECU uses the Idle control Valve to control the amount of air that is allowed to bypass the throttle body supplying air to the intake manifold, so as to keep the engine idle speed constant.
Lots of articles on the internet explaining its function.
It is a service item on our cars that needs to be cleaned regularly. It can be tested. Here is a page on the subject:
https://993servicerepair.blogspot.co...r-robbing.html
Andy
Instructor
Joined: Feb 2015
Posts: 131
Likes: 22
