1995 854T Is it ok to unplug the IAC short term?

[alschnertz]

As I continue to search for my rough cold start problem...

I found that if I disconnect the IAC plug, the car runs smooth at startup.
The CEL came on - which I expected since the IAC was disconnected.
The warm idle (IAC still disconnected) is around 1150-1200 rpm.

I guess I'm leaning toward an IAC failure but while I'm still diagnosing, I'm wondering if anything will be damaged by having the IAC disconnected while driving.

[cn90]

Take the Idle Valve out of the car, give it good clean with carb cleaner.
This should solve the problem. It is a 10 min fix.

To answer your Q, probably fine driving with the thing disconnected for a short while.

[erikv11]

+1.

Definitely try cleaning the IAC before going any further, it is a common problem. Spray a lot of carb cleaner in there, cover both holes and shake it until the internal barrel rotates easily, you can hear it. Dump out the cleaner, repeat. It will take 10 minutes just to get the IAC out but this is definitely an easy, quick job.

The IAC is held in by Oetiker clamps from the factory so you will need two new clamps, just get screw type clamps. I would probably replace all 4 clamps, it will just make it easier getting the IAC out, but check out how it goes for you.

[alschnertz]

Thanks.
I've done one round of cleaning (I should have mentioned that) but I can certainly do another - maybe something got jogged loose with the first.

Is there a diagnostic test that I can do on the IAC? Like a voltage test similar to what you would do on the throttle position sensor or the AMM? I didn't find one with the search.

[cn90]

You can use the procedure below to check the ohm readings.

This is an electro-mechanical device. You only check the "electro" part using the link below. The "mechanical" part can only be checked with a screwdriver to be sure it moves freely:

http://www.justanswer.com/volvo/2f4ka-c ... e-bad.html

Get a used one from junkyard for $10. Ebay has a whole bunch listed for $25, just make sure you buy one from a low-mileage car. Anyway, I doubt if you need a new Idle Valve.

[alschnertz]

I think I'm on to something.
I removed the IAC this afternoon to give it another cleaning.
When I went to reinstall, I noticed that the top hose is split where it connects to the vacuum tree.
For now, it's wrapped in teflon tape (along with the hose clamp). We'll see how it is in the morning.
Feeling good about this.

Would someone have a part number for this top hose that connects from the IAC to the vacuum tree? I looked it up on FCP & Eeuroparts but didn't find the upper hose.

[cn90]

The PN for this hose is 9146225.
About $8 at Volvo dealer.
Don't buy aftermarket junk.

[alschnertz]

As tight as things are, I still don't throw money away on inferior parts.
Thanks for the part # and the link to the diagnostic test.

A few comments on the test though...
Disconnecting the battery should not be necessary when checking the IAC as the plug is disconnected when performing the test.
And when testing the plug side, I think they mean the car should be running - not just the "ignition on".
Plus, when testing connector # 3, the instructions refer to connector # 1. It's a little confusing.

[alschnertz]

You can use the procedure below to check the ohm readings. http://www.justanswer.com/volvo/2f4ka-c ... e-bad.html

Has anyone else done this diagnostic test?
I tried it and the IAC itself passed but the readings from the plug did not.
#1 to ground read 0v and #3 to ground was infinity. Would that mean that the ECU is bad? Or did I just do the test wrong?
What sends voltage to the plug?

Other than cold starts, the car runs very well. Returns 22-23 mpg around town.
I didn't change the hose yet, and will, but I was surprised at the test results above.

[erikv11]

Cold start problems can often be traced to the ECT. Do you know its vintage? Maybe swap in another one from the junkyard.