Hello out there!
1990 420 SEL, Can anyone tell me if the Thermal Vacume Valve can effect idle in anyway or is it just for emissions control and therefore totally unrelated? I have rough surging idle and one of the tubes on this valve is broken off. Ive read where others have just plugged this valve and the hose leading to it.

Thanks

Vacuum leaks can effect the car's ability to idle.

Most of the vacuum switches/valves that are only related to emissions control. Just follow the lines and see if they go to the smog pump or EGR /etc.

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