240 DL sedan 1989 B230F 235K kilometers (~140K miles)
original, very well kept, not tampered with

Recently when I start the engine cold, it idles at 450 or so unsure RPM for around 5 seconds, then goes up to the expected 750 or so and idles fine. In addition, the FIRST pressing of the throttle from stop almost stalls the car if anything more than a very gentle foot. After that, it drives fine, and takes off perfect from a stop.

The car has no history of such problems, and has always driven very well.

I'm thinking IACV, but not sure. I replaced the AMM last year, my old one was dead, with a junker, and the replacement worked perfectly. Hoping this is not AMM, rather expensive and limited part up here in Canada.

Does the IACV just open/close to allow air into the intake past throttle? Is there a motor in there? Silanoid? Does the wire contact on it often go bad?

Looking for some advice, thanks!

Greg Mustang
Montreal - Ottawa
Canada

Greg, are the mornings getting chilly up there? Because those symptoms could be due to too little gas getting to the cylinders on cold/cool starts.

The reason (I'm told) is that some of it gets soaked up by porous deposits on the back of the intake valves -- maybe in the ports too(?). So even though the ECU tries to give extra fuel, the cylinders don't see it right away.

They do see it as soon as the deposits get saturated and let all the fuel pass to the cylinder. Only cure is to run something like Techron in the fuel for a tank or two.

Its most effective on short trip driving, as opposed to long trips (lots of run-soak-run-soak episodes.
--
Bruce Young,
940-NA (current)
'80 GLE V8 (Now gone)
'83 Turbo 245
'73 142 (98K)
'71 144 (track modified--and still here)
New 144 from '67 to '78
Used '62 122 from '63 to '67