This appears to be a common issue with the w126 models. Idle issues and vacuum leaks. But I can’t quite narrow this one down. Normally, it idles perfect. Very quite and smooth. Every so often, if I left it in park…….walked away for awhile later and return…….the car would be dead. No longer running. Then it began to occur more often. Then much shorter intervals….when parking the car. I’d put it in park and the idle would surge up and down like it’s trying not to cut off. Sometimes it’ll recover. Sometimes it will die. Here recently…..when I’d come to a stop light, while in drive………it died. So whatever it is….it’s getting worse.
I have not adjusted the idle/air screw. Not sure if that’s an issue, since it idles perfectly when it does. The Over Voltage Protection relay may be a problem, according to this video. When I remove it….the car does not respond at all. Oh yeah……forgot to mention. One time recently when I got into the car, no windows or roof would work. I revved the motor and all of a sudden, there was enough voltage to activate them. So there is a voltage issue………….OVP Relay?????
