Question about 1988 Mercedes-Benz S-Class

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Adjust fuel mixture for 420 sel 126 Mercedes 1988

Hi there I am trying to find out which way to turn the adjustment srew inside the airfilter hole which regulates the mix. is it rich turn right so that would be clockwise or the other way. I have installed a hydrogen supplement system so I like to fine tune the runnnig now, I feel it is still a bit rich as I see on the exhaustpipe colour. Many thanks if someone could help. Peter
Ps I hope this car has no sensors for it infection system which could make the use of my supplement system less or not workable. Any clues on this one as well

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Clockwise is leaner.

Posted on Oct 20, 2009


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At the rear of the alternator is a little D-shaped hole near where the two wires plug into the side. With the engine running, insert a short copper wire into that hole - it should only go in about 3/8" or so. There's a little contact inside, and the point of this procedure is to intentionally short-circuit that little contact to the body of the alternator. If the regulator's good, you should suddenly hear the engine labor a little, or hear the fan belt start squeaking a little like it's working harder than normal. When that little contact is shorted on a good regulator, it tells the regulator to charge 100%, full-bore. Voltage should rise sharply while your wire's in there.

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My car is running rich

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I have done just about everything to make it pass smog but it still runs rich. What can I do to make it pass?

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Engine is shaking and will not stay running in gear. I had the ignition module checked and it passed the test, I had the coils checked and they said they also passed the ohms test. I replaced the spark...

this does sound like a timing issue or the points in the ingition system are not set to the right gap. if the ignition leads look perrished they should be changes as sparks for the plugs might be shorting out on the engine case and not the plug. or from the coil to the distrbutor. i would check this first before playing with the timing.

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