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4 Posts
Discussion Starter · #1 ·
Hey guys, it appears I've got the typical IACV issues; stalling when coming to a stop, doesn't idle perfectly when A/C is on.

Can someone post a picture of the IACV's location, and what is the best method for removing/cleaning it without taking the engine out?

Anyone in Melbourne, Australia who can help me with this issue?

3 Posts
Hello there, i found this procedure in the pages of a Nissan Club in mexico, so make the translation from Spanish an post it
hope this helps

The IAC, Idle Air Control (idle air control) is the #2

This valve is actually the set of 3 components;

the IAC, Idle Air Control (idle air control)
It is the main one in charge of maintaining the idle speed at the pre-programmed speed in the computer.

The FICD; Fast Idle Control Device the latter is activated when the air conditioning is turned on,
compensating the load to the motor.

And finally the idle adjustment screw, whose name explains its function.




The valve is supported by 4 10mm head screws, 3 are short and one long on the highport engine,
and with air conditioning, you will have to use your hands in ways they never imagined,
to be able to access these screws,if you remove the oil filter, it will make the task a little easier (I didn't)

In the following photo you can see the distribution of the screws,
it always helps to know what the part to be disassembled is like, when we cannot see it completely.

Screws 1 and 2 can be removed with a ratchet, 1 without extension, and 2 with a short extension, the movement is reduced,
but once loose, they can be removed by hand. Throughout the work, see with which hand, and in which direction it should be used,
sometimes they will need to put the left facing the engine, or from different angles,
patience,Either that or remove the AC lines (owners of lowport, don't worry)

Screws 3 and 4 come out using the 10mm key, you can use a mirror with the right to see, and with the left put the key from behind,
in the direction of the fire wall, towards the valve, or they can feel the screw, by hand, and then put their hand back with the wrench,
and locate it using your muscle memory.

Disconnect the 2 electrical harnesses and remove the valve, it also serves to disconnect it first, and it makes a little more space for the tools.
Once the valve is out, this is how the intake manifold remains, note how the old gasket remained apparently intact, but adhered to the manifold


Here is a view towards the inside of the valve, notice the carbon residues from the exhaust gases that are recirculated,
if you no longer had EGR, you will not have to worry for a long time about this,
also note the actuator and the 2 openings of the stem coming from the solenoid with carbon residue.


Now we must proceed to disassemble and the valve, we remove the IAC by removing the 2 Phillips screws that hold it,
be careful because inside there is a small spring that tends to jump and get lost.


Then the stem that remains attached to the valve is removed, pulling it carefully, it is supported only by a blue gasket,
the removed parts look like this


They must be well cleaned of carbon residues that could prevent the actuator from moving freely within this tube,
As you imagine, when going down it lets the air pass through those "windows", all this controlled by the car's computer.


Now using the 19mm wrench and some cloth to hold the valve body, remove the FICD

There is not much to do to this solenoid valve, just check that it returns to its original position quickly when we depress the actuator
(that the internal spring works well), and clean carbon deposits from the seat of the small valve on the tip.

Later they can connect momentarily (by pulses) each of the valves to a 12v source (car battery) and check that the valves work,
they should move, and return to their original position with ease. Remove the idle adjusting screw from the unit (I owe you pictures)
this is basically a plastic screw with an o-ring near the end, this measures how much air is going to pass through said valve under normal conditions,
clean it very well, this in my case had a lot of carbon.

You may have noticed how tight or difficult it is to move this plastic screw, which causes it, to damage many times, if not already.
grease the o-ring and with silicone-based grease, since it does not attack plastics and rubbers,
if you put another type, there is risk of damaging the screw or o-ring, once greased, it will turn more easily.

With all these components out of the body of the unit, clean the aluminum part well of carbon, with degreaser, carburetor cleaner,
or even acetone works, clean all the ducts well, inside the piece.

Once everything is clean, you have to assemble the solenoid valves, and put them in their place again, the same with the idle adjustment screw.

Then you have to put the valve back in the intake manifold, all this is the reverse of how was removed it,
make sure both surfaces are clean, and apply a THIN layer of silicone to the part,
if there is someone who does not like to use silicone in the car it is me, but given the condition of the car,
and that the original gasket, takes months to arrive, or is its difficult to source, opt for this method.

The valve must be screwed in little by little, in a crossed pattern as they would with a rim,
try not to tighten too much, but do it enough so that there is no leak, and very carefully,
the last thing waiting to happen is to damage the treads into the aluminum manifold,
place the valve and let the silicone dry if they used it.

Connect the harnesses, it is worth checking their condition, see that the contact is good and they are not sulfated or greasy.

3 Posts
ARV Air Regulator Valve # 1

Inspect this valve in case the car idles very high when cold, or it cannot be lowered below a certain level with the adjusting screw. The function of this valve is to keep idling faster than normal when the car is cold, providing an air bypass, which closes as the car heats up, consists of a bimetal, this is a pair of metals with different coefficient of thermal expansion, that when heated or cooled bends to one side or the other by moving the valve, and a heating element, which when starting the car begins to heat the bimetal, which closes the valve This valve is located at the bottom of the intake manifold, so you have to lift the car, either using a jack, or on ramps, or as they feel safe and have room to work underneath If removing this valve is easier, it is only somewhat uncomfortable to work upside down.

From below, on the passenger side, looking in a very obvious space that there is, you will see the intake manifold, and screwed down, a valve, to which 2 vacuum hoses are connected, and an electrical connector




The vacuum lines are removed by releasing the clamps with the pliers, it helps to loosen the hose on the manifold side as well, for more flexibility.

The valve itself is fixed to the manifold by 2 10mm screws, which are easily accessed with the ratchet, socket and an extension,
It is easier to first release the valve from the hoses and then remove the electrical connector.

Once removed the valve looks like this


Inspect how much light passes through it, so that you get an idea of how much this valve is open with the car cold.


Then proceed to open it by removing the 4 screws that hold the plastic part to the metal part, be careful with the joint Once open this is appreciated:



Check that the spring is hooked, there are cases in which the spring comes out and the valve no longer closes, move that brown phenolic plate with your finger,
in the opposite direction that the spring pulls it, and see if it moves freely, it may happen that the whole assembly is dirty
Although it was not my case, you have to check it and clean it if necessary.

You can test it by putting it in the refrigerator or freezer for about 15 minutes, and see how the opening gets bigger,
this is theoretically what should happen on very cold mornings, then connect it to the battery directly,
and this must be closed COMPLETELY within 1.5 -3 minutes.

It is also necessary to check that the resistance of the valve is 70-80 Ohms
If it does not close completely, or as it was in my case that the opening that had at room temperature raised the idle to 1500 rpm
(although apparently it was a very small opening), you have to close it a little,
this is done with a nut on the back that controls the position of the axis of rotation of that insert,
This nut is filled with a red glue that must be broken to loosen it, you must use the 7mm wrench.

You can see that the hole through which the screw passes from where we remove the nut, is not circular, but a kind of slide,
try moving the screw to one side or the other of the play that the gap allows, immediately it shows as depending on where it is fixed,
the valve closes more or less. It worked very well for me to leave it open at room temperature 1mm at its widest part.

Now, no matter how cold the mornings are, my idle starts at 1200rpm and after a few minutes it is at 800rpm as usual.
Close your valve again with the 4 screws and blow on one side, a little air must pass through, but not too much, and with a little resistance,
Now blow and cover the other end, check if there are no leaks at the union of the 2 pieces, in that case make another joint,
or use the silicone, fortunately this gasket seems to reseal well.

Now it's time to put it in the car in reverse of how they removed it, I took advantage and put it with new vacuum hoses.

Once the car is assembled It never hurts to ground the MAF again when there are idle problems (probably before doing all of this)

Adjust your idle:

Start the car, let it reach its operating temperature
Accelerate to 2000rpm for 2 minutes
Turn off the car
Disconnect the TPS (throttle position sensor)
Start the car
Give 2 or 3 accelerations at 3000rpm
Adjust the idle speed with the screw, leaving it 100rpm below what we want (the manual specifies 850 + - 50)
Turn off and connect the TPS

Restart and enjoy your new car idle


3 Posts
MAF Sensor Grounding

Written by Jim Wright

First, you'll need a digital voltmeter and a small flat blade screwdriver.

The MAF sensor is located just past the air intake. You'll need to pull back the rubber cover to expose three wires.
On mine, the outer two were orange, the middle one is white. The middle pin is where we need to get a voltage reading from (with the engine idling).
Take the positive lead of the voltmeter and make contact with the middle wire.
The negative lead should be pressed to one of the ground connectors on the engine block, near the firewall, right behind the fuel injectors.
You might have to look hard to see them, just look for a bolt with several black wires running to it. Took me a while to spot it myself,
several vacuum hoses in the way...

The voltage read should be less than 9mv (.009v), if it is above this value, the sensor needs to be regrounded.
To do this, a wire needs to be run from the middle pin to the ground lug. You'll need to remove the connector from the MAF to get a good angle on it.
On either side of the connector is a small opening for a small flat blade screwdriver. There is a wire that runs around the connector to hold it in place,
you need to pry this wire outwards, then move the connector back a bit. Do one side, then the other, and it should pop right off.
I'd never seen this type of fastener before, once you have it off you'll see what I mean.

You'll want to solder a new wire to the middle pin, make sure you get a good connection. Then, run the other end to the ground lug.
If you want to do the job right, you'll want to get a connector from an electronics store that has a ring that you can crimp the wire to.
I don't remember the size of the bolt, so I'm no help there. I just looped my wire around the bolt twice and put it back on.
I may go back and fix it up nice some other time.

Once the sensor is regrounded, the voltage should drop significantly. Mine was at around 11mv, after the fix it went down to less than 2mv.

2 Posts
Hi guys..I'm from south Africa..I have a Nissan Sabre 200gxi....not sure if you familiar with this South Africa these cars came out in 1995....SR20DE high port....I've recently bought myself a SR20DE RR I'm has a number 2J2 on the side of the head...I'm looking for someone to help me wire it up with the existing computer box....can any aid me please..would really appreciate it alot...
Old motor out and the newer motor in which I'm assuming it's a RR motor
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