mapolus

Hey all...does anyone have a method to test the idle control valve? The car runs well, but intermittently idles at 1500 rpm after warming up. It will drop to 850 rpm for 2-3 minutes, then back to 1500. I've gone through all the hoses looking for a vacuum leak, but nothing obvious. Any other thoughts? Thanks y'all! Matt

TT Surgeon

My 930 used to do that, it was the afr mixture, was running super lean.

Metal Guru

Do you mean the axillary air valve (AAV)?
It's the device on the right side of the engine, on the top, with an electrical connector, a supply hose running from the i/c and an output hose running into the intake. It provides additional air to the engine, speeding up the idle a little to overcome the friction of the cold engine. The electrical connector supplies power to a bi-metallic strip which, as it heats up, closes off the orifice in it at a rate that is roughly the rate of engine warm-up.

To test it, start the engine and immediately pinch the hose from the valve output to the intake. The idle speed should immediately drop around 200 rpm.

mapolus

Thanks Paul...that must be it (is the ICV just a 3.6L NA part?). Anyways, how do you get your arm back there to pinch the hose while it's running??? Maybe I have fat arms, but I can only reach the I/C hose. Thanks again!

Matt

mapolus

Chris, I'm not counting anything out at this point...how did you diagnose that and what was the solution? Thanks...

Metal Guru

There's no IAC on CIS cars.
Pinch the supply hose on the right side of the I/C.

mapolus

Okay...thanks for the testing tip. The idle does decrease about 200ish rpm when I pinch the supply hose. I took the IC off and checked all the hoses. Drove about 150 miles this week with no idles above 950...so hopefully it was just a poorly seated hose or clamp. Thanks again for the help!

MFuller

Was this issue ever resolved?

mapolus

Yes, I'm sorry for not being more clear in my previous post. My original confusion is that Adrian's book led me to believe there actually is an ICV in our cars -- there is not. Per Paul's recommendation, I checked to see that the auxiliary airflow regulator was working (decreased rpm by 200ish when I squeezed the supply hose on the right side of the IC). So, I took the IC off and made sure all the hoses were tight...there was one loose worm clamp that I must've missed when I replaced the air pump filter (not sure it was ever previously replaced...it certainly looked 23 years old). Fortunately, it hasn't idled above 1000 rpm since then. Yes, intermittently still above the 840-920 tolerance, but something that can wait until I get back from this deployment.

I wish I had more of a smoking gun, but I don't.