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Re: auxiliary air valve: repairing[200/81] posted by Bill Bradley on
Monday, 3 January 2000, at 10:28 p.m.
Sure. On some of the AAVs there is a stud which holds the valve in place. Over time either the spring weakens or the slide slips in the case, so the valve stays closed.
Soak the stud in penetrating oil for a good long time (like overnight) and then loosen it. Use a screwdriver to open the valve about 50% of the way and then tighten the stud again.
I've done this on Volvos, VWs and BMWs and it's cured the slow cold idle on all of them... the only hassle is that is you break the stud by overtightening or by using too much torque to lossen it, the whole thing is shot.(but they're cheap and easy to find at boneyards)
Bill
'84 245Ti
'84.5 242Ti
'83 244DL
Don't worry about the other post, he's talking about the idle control motor which was '82-
Re: AAV, NOT CIS motor![200/81] posted by abe crombie on
Monday, 3 January 2000, at 11:08 p.m.
You are absolutely right. My brain was stuck on the constant idle speed motor setting.
The AAV is a hole with a "V" profiled rotating disc blocking the opening. There is a spring that pushes the disc towards the closed direction and a bimetal (thermostat) spring wrapped by a heater wire pushing towrds the open direction progressively with colder temp.
The wire is fed by the circuit running the fuel pump(s) and heats the bimetal spring allowing it to close as engine warms up.
For no high idle cold do Bill's trick. The crankcase vapors get into the valve making it oily and gumming it up and are somewhat acidic causing corrosion that can stick the disc.
If you have high idle on cold start that slowly goes down as engine is run for lengthy time then you need to check for 12V feed and ground and see if the resistance between the two pins on connector is 15-30 Ohms. If it is open it is junk. If no 12V feed then trace why.