1990 nissan 2x4 double cab.

AstroTurf

AstroTurf

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What is this thing on the engine?

20140505_115636.jpg

It's bottom right of this image.

20140505_115820.jpg
 
AstroTurf said:
I have no idea, it's a friends car and he wants to know what it is and does.
Apparently Nissan refuse to tell him.
Click to expand...

:wtf: - time to haul out the manual - knock sensor sounds about right - probably find that none of the mechanics at Nissan were born in 1990. :p
 
I sent the pictures to Nissan Parts person that I know. He checked the EPC and reported back that it's actually a Cold Start Valve.
 
It's an idle control valve to keep the car idling constantly when the car is cold, you turn the wheel and the power steering pump requires some extra power, air con goes on and off, etc. Almost all cars have them. It's basically a second throttle valve which is electronically controlled to keep the vehicle's motor ticking over smoothly as the ancillaries running off the motor come on and off and to compensate for temperature and pressure variations.
Idle control valves are usually mounted close to the throttle on the intake manifold.

Knock sensors listen for denotation, premature ignition of the fuel inside the cylinders. The sensor must therefore be inside the engine block. It is small and screws into the block so you will only see the electrical connection protruding from the block. It is essentially a microphone.
 
Thank you all for the advice and information. Greatly appreciated :)
 
DanH said:
It's an idle control valve to keep the car idling constantly when the car is cold, you turn the wheel and the power steering pump requires some extra power, air con goes on and off, etc. Almost all cars have them. It's basically a second throttle valve which is electronically controlled to keep the vehicle's motor ticking over smoothly as the ancillaries running off the motor come on and off and to compensate for temperature and pressure variations.
Idle control valves are usually mounted close to the throttle on the intake manifold.
Click to expand...

It's like an old school choke.
 
ponder said:
It's like an old school choke.
Click to expand...

A choke manipulates the mechanics of the carburettor by restricting the air intake so that the air pressure is lowered and air speed is raised. In turn the air fuel mixture gets richer.

Basically the engine has to suck harder to get air and in turn sucks in more fuel per unit of air than it usually would.

The idle control valve actually let's more air in while a choke restricts air flow.

At cold start the electronic control unit of the fuel injection system will see a low temperature on its temperature sensor/sensors and apply a corection factor to its fuel map which will widen the injector pulse width to squirt more fuel per unit of air inoder to enrich the air fuel ratio. It will also use the idle control valve to regulate the idle speed.
 
Yeah yeah yeah but they both come into play for similar reasons, end of the day you end up with a richer mixture.
 
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