Howdy,
My 240 GL Wagon has a high Idle problem.It was idling perfectly at 900-950 then Itook it in for service and the mechanic cleaned the throtle body and replaced the brake booster. When it returned, the idle speed was much higher(1400rpm in neutral). I took it to the shop that did the service/repair and they fiddled with it. The mechanic removed the vacume hos to the IAC valve and it went down to normal. I believed that if this hose was removed that the speed would increase? They sprayed some carb cleaner into the IAC valve a couple of times and the IDle speed reduced slightly and now sits at 1100-1200 RPMs. IS the valve the culprit and how do I check it? MAny thanks for any help.
ROb-Sydney AUstralia

The shop is probably one not familiar with your car. After cleaning the throttle body they failed to properly set the TPS (throttle position switch), so the IAC is never engaged.

Quick check: Use a large pair of pliers, and squeeze gradually closed one of the vacuum hoses to the IAC. If the idle slowly drops, and - in fact - the engine dies if the hose is closed completely, it is the TPS.

Check the IAC: Key off. Remove the harness connected to the IAC. Use an ohmeter to check for continuity between each pair of contacts. (I can't recall if your IAC is a 2-wire or a 3-wire type.) If it is OK, the TPS must be reset and your idle should go to normal 750 rpm.

Good Luck,

Bob

:>)

Even easier. With the car off slowly turn that silver sheel on top of the intake manifold that the throttle cables are attached to. When you first begin turning it you should hear a faint click. Then when you let it go back to the resting position, you should hear it click again. That means that the throttle position switch is being engaged.

It's possible that they removed the TPS and didn't reinstall it in quite the correct position when they cleaned the throttle body. (Not that they needed to remove the TPS from the TB to clean it.)

The little bar that goes down in front of the TB, linking the throttle wheel down to the actual throttle is also adjustable, and could be too short to allow the throttle to close all the way, but I doubt they messed with that.

Another thing to check is the black, plastic idle adjustment wheel on the bottom of the TB. This might have been set to a good position for your dirty TB, but now needs to be turned to work well with your clean TB.

I wouldn't focus on the IAC first, I don't think that is your problem.
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Andy in St. Paul. '89 244 147K mi, '91 745 Regina 202K, '87 245 lost to rust at 225K

Hello Rob; Check out the tune-up and performance section in the 700/900 FAQ in the pull down Features section at the top of the page. The engine management/FI system ( LH 2.2/2.4) are pretty much the same on the 200 series. Lots of great info.
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Gary Gilliam Sumerduck VA, '94 940 na Regina 150k, '86 240 180k