I have a 940 16v, 130,000 miles.

It runs like a top, doesn't burn oil, doesn't leak, makes great compression and is maintained perfectly IMHO.

However the idle has always been a bit low and lumpy.
I tried again the other day to make it idle smoother.

I cleaned the mass air flow sensor with the proper stuff, cleaned the throttle body again, checked for any vacuum leaks of which there are none, and checked the timing which was fine.

It still idled a bit lumpy at 700rpm.

I finally turned the idle srew up and adjusted the TPS so it clicks right when you open the throttle.

No change in idle. Then I adjusted again, no change. I then went hell for broke and adjusted it way open and as far as the TPS could adjust. Initially it was the same 700rpm idle. Then after the test drive ( I test drove each time I adjusted it) the idle shot up to 1500rpm. Progress I thought.

So I turned the idle screw down to about half a turn more then stock. No idle change again. Still 700 and lumpy. Unplugged the battery so the computer would reset and then test drove, still no change.

No matter what I do to the idle screw and TPS, the idle stays the same.

Im confused, any suggestions?

My bet goes to the IAC, but not sure if the 960 IAC is the same. I cleaned mine with throttle body cleaner being careful not to get the fluid or crud in the motor or connections. It should swing freely inside the housing as a gauge when it is clean. Be sure to blow it with compressed air to get the crud from the workings, and let it sit on a towel to drain and dry before re assembly.

Dear Tom87

Hope you're well. Have you cleaned the Idle Air Control Valve. This is mounted next to the intake manifold, below the throttle spool. It has two rubber hoses and a single electrical connector (on the end closest to the firewall). One of the hose openings points downward, the other faces the radiator.

Over time, dirt (black, oil residues) accumulates in this valve. The valve does not operate smoothly, causing rough idle, or, in an extreme case, a failure to maintain idle.

This valve may be cleaned using cotton-tip swabs and brake cleaner. If You choose to soak the valve, to loose oily deposits, be sure to keep the solvent depth such that solvent cannot get into the motor compartment.

It is better to use swabs wet with solvent to clean the valve's chamber. You can use a wooden or plastic rod to hold open the valve. Do not use metal tools inside the valve.

If You want to use a jet-spray, keep the nose of the valve pointed down (towards the ground), to keep solvent from getting into the motor compartment.

When solvent runs clear, all dirt, etc., has been flushed-out. Allow the valve to dry and re-install.

Hope this helps.

Yours faithfully,

Spook

Im going to try that tomorrow. i wasn't going to mess with it at first, but ill give it a shot.

Okay I took the idle air control valve off the car and gave it a thorough clean with throttle body cleaner. I made sure to keep the connector end pointed up. It was filthy. I also cleaned in electrical connector and the two hoses.

It must have been dead or stuck before because now when I start the car, it idle at 800rpm and then shoots up to 1500-1600rpm.

I adjusted the throttle body adjustment screw down so that the throttle was closed. I also tried adjusting it 90 degrees open from close like the FAQS suggested. The TPS is adjusted properly.

It still idles at 1500. When I put my foot on the gas, it the IAC seems to cut out and the engine is only taking air through the throttle plate. When I take my foot back off the gas it immediately jumps to 1500 again. So the IAC seems to be working now.

Can anyone suggest if maybe the IAC isn't working right? I am thinking of unplugging it for now and just adjusting the throttle to 900rpm again. Its not really safe with a 1500 rpm idle in traffic.

Okay I had another poke at this problem today.

I adjusted the throttle so it was closed.

The car starts idles perfectly. I drove a few miles and just as I am getting home it shoots up to 1500 again.

I then unplug the IAC and the engine rpm starts going up-down-up-down-up-down between 1300 and 1500 rpm, like a switch being turned off and on. I don't even know how it could do this.

I plug the IAC back in and it stays steady at 900rpm, which is where I want it.

However I know its going to keep randomly going to 1500.

Any ideas?

Some of the idle motors are hard to really clean I think; I've had a bunch and some just don't really work well. Also, in the FAQ there is info about disassembly of the older model with pics, that show a nasty mess in the motor area. THe newer ones can't be disassembled so I have been making sure that cleaner gets down in there by filling the openings and tilting it. On one I let it soak completely for several days with a lot of pblaster, and it has been working great for a year.

Well I definitely have the one that can't be disassembled. I think cleaning it jogged it to life but I can't have the car idle at 1500.

Im in school right now and don't have a spare 250$ for a new IAC right now.

What I have done is adjusted the TPS so the computer always thinks I have my foot on the pedal even with the throttle closed. That way the IAC doesn't come on and the car idles at a permanent 900rpm. Nice and smooth. Not a permanent solution though.

Cleaning everything did eliminate the lumpy idle though.