Hello,

There's one thig that's getting on my nerves about the startup of my Golf 3 (mechanic 1.9 TD) and maybe somebody knows the reason of this wierd behaviour:

When you start with engine cold the engine works at low rpm (around 780) and as soon as you pass 200 meters, you hear some relay click and rpm increase to around 850.

I lowered the minimum idle spped to 850 (it was around 1000). It is a mechanical idle adjustment: there is minimum (which I adjusted) and maximum stop screws, and the main adjustment where you adjust the cable on a solenoid that moves between min and max, i suppose, dependantly of outside temperature (electronically controlled).

The thing I don't understand is what's the reason to keep the engine at low rpm when cold; it would seem logical to me that it should be just the opposite: the engine should lower the rpm when it's warmed up! And also I don't understand the mechanism ot that happening: the idle (throttle) valve is obviosly at the minimum stop screw in both cases, because I lowered it by adjusting that screw when hot and the cold idle also decreased. So, what thing does that clicking relay control that increases the idle?

PS To be less confusing:

There are two idles:

1. startup idle: the lowest one, before the relay clicks, regardless of the outside temperature,
2. normal idle: higher on cold days and lower on warm ones.

The question is: what causes the first one?

Edited by hrvoje dagelic on 06/11/2010 at 17:51