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Trying to adjust choke

2891 Views 17 Replies 8 Participants Last post by  crickle
Hey there,

I have a 1989 560SEC and just moved up to the Central Interior of BC, Canada, from being on the coast in Vancouver, BC. On the way up the car started choking up and becoming sluggish. I've been informed by a few people that my air/fuel rate needs to be adjusted. When in idle it sputters and then eventually shuts off. When i pull up on the choke a couple millimeters it idles smooth. I am completely new with Mercedes and I am having a hard time figuring out how to adjust the choke.

Any help will be appreciated.
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No I think they are right. Sounds like your mixture is too rich. There is less oxygen at higher altitudes. But 3000ft elevation change shouldn't affect it much unless yours was off to begin with. Your idle control valve is probably not opening up properly either. Take it to a Mercedes garage and have them put on an exhaust gas analyser and adjust the mixture screw on the fuel distributor. Don't try this at home unless you keep track of your changes. Very subtle adjustments and each adjustment takes a few minutes to take affect.
Yeah sounds right. In the future, don't let people touch the mixture screw. Its calibrated to the rest of the car and set at factory. You can only set it correctly when all the other induction and ignition components are working at 100%. If you try to adjust it on an old car with varying degree of service life to the rest of the induction system you're bound to mess it up.

You can buy a wideband o2 sensor with a gauge for about $200. Innovate Motorsports Wideband Air/Fuel Ratio Tuning
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