Bad idle before warm up

[Tomca_]

Hello everybody,

I have a 1990 Volvo 740 GL. Motor type is B200E, K-Jetronic system. The car ran 250000 kilometer already, but still OK.

I have a strange symptom on the car: when I start it and the engine is still cold, it starts fine. Cold starting idle is 1000 RPM. That's OK. However, after 1 minute, the idle speed begins to decrease and after another half minute, the idle speed decreases to about 500. The car begins to shake and I have the feeling it wants to stop. So I gently press the gas pedal to increase the RPM to an acceptable level.

The idle speed becomes normal (about 850 rpm) after several minutes, when the motor is already warmed up.

If I start the car with warm motor, there is no problem.

What could it be? The warm-up regulator? The thermostat? The cold-start air-valve?

Thank you any help in advance.

Tamas

[wojeepster]

try cleaning the idle air motor under the intake manifold. One electrical connection two hoses connected to it. Use carb cleaner and lightly lubricate afterwards.

sorry just noticed k jetronic idle motor on valve cover shutter type but otherwise about the same