Cold weather and fast idle in AM

[Paul Crowther]

It's winter again and I remember from last year it taking much longer for the idle to drop to normal as the engine warms. I'm guessing it's the WUR but haven't dug into diagnosis yet since it DOES idle back eventually. It hangs at 2000 rpm for a good 30-40 minutes before slowly coming down. I know that's not right. Since in driving I'm at 2400+, a 2000 idle isn't noticed except at stops.

I'll be looking at diagnosis articles later today, but does anybody want to steer me in a particular direction?

[ManniB]

Paul,

the WUR enriches the mixture when cold. What makes the engine run with a faster idle is the Zusatzluftschieber (auxiliary air regulator). When the engine is cold, it opens a path for air around the Drosselklappe (throttle) whick lets it run faster. There is a bi-metallic element AAR is electically heated which closes the AAR and drops the high idle after several minutes. Either the electical connection of your AAR or the coil on the bi-metallic element may be faulty. Use the search function for more information.

- Manfred

[Paul Crowther]

thanks, Manni. Have already found much info and learned a lot more about the AAR system. Will check things out.

Doesn't seem that complicated, but what I haven't found is a good description of how to actually test the electrical portion of the regulator, such as where to connect your tester and specific about power on/off, etc.

[kodioneill]

There's a fix for the additional air valve for a high idle if your aar is in spec. Pull out the aav and using a socket squeeze it in a vice crush it down 1/8 ".