unstable idle - idle valve question

[areznik]

It was a very nice spring break in Florida. I drove 2350 miles in one week on my Q45 '94. It behaved pretty well besides unstable idle. I took it to the dealership in Orlando, and they raised the rpms to solve the problem. It worked for one day, and then the problem reoccured. After talking to them, they suggested that the idle valve may contain carbon in it, which produces unstable idle. My questions to you guys is, can I clean this valve somehow? Before the trip I took my Q to local nissan dealership to clean the fuel and air systems with BG service. Is there a way to check this valve for proper operation? Unstable idle problem tend to appear when the engine is cold, but sometimes it appears after driving the car for awhile. I have new injectors, egr valve, fuel pump, O2 sensors, valve cover gaskets.

Any reply or thought would be greatly appreciated, Andre.

[maxnix]

The IAC and EGR valve hoses can both be cleaned. There ar previous posts on how this is accomplished.

Compensating for dirty intake path and throttle bodies, along with the above mentioned valves, should be avoided as cleaning the out of specification dirt will return the system to its proper operating parameters.

[Q45tech]

When ever the IAC is removed always ALWAYS replace the mounting gasket.......it will tear and leak air.

[MattB]

When ever the IAC is removed always ALWAYS replace the mounting gasket.......it will tear and leak air.

Is that just for the Q or for all cars?

[DAEDALUS]

It's a good rule to folllow for all gaskets. Even if the chance of a leakage was "only" 5%, it's not worth taking for what they cost, especially when you consider the amount of labor involved to replace them.

[elwesso]

Cleaning the IAC should be really simple..

Get a new gasket from Joe ($1).....

Then just remove the IAC with the 4 bolts, pull it off, and go crazy with carb clenaer... You should use compressed air... Spray the carb cleaner, then spray out with air... repeat until no icky stuff comes out...

THis is how I did it..

[Q45tech]

Disassemble the IAC, pull the bypass screw out and clean, screw and channel.

Time consumming to clean the solenoid plunger and channel with tiny brush, lots of solvents.........make it look brand new.

Then bottom the bypass screw, then turn out 2.5-3.5 turns.