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Discussion Starter #1 (Edited)
I did the adjustment on my 92 300e...I used a multimeter from Sears I did the 50-55 % adjustment and it back fires through the TB like hell, I take it that is to lean, now this is a California car so I presume it the same kind of adjustment. I had it at 82% AND MY WIFE SAID IT WOULD HARDLY GET OUT OF THE WAY OF IT SELF..so now with it warm it is at approx 65-68% and seem to be doing good...but 50% is out of the picture fellas , for me anyway.
 

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'84 300D/ dakota benz trk. Sold... miss it. "88 260E '91 190E 2.6 '89 Volvo 240DL "85 300D
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i adjusted wifes 260e to 48/53% helped it alot. however, if i were you, i like results not numbers. i would run what runs best.
 

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'84 300D/ dakota benz trk. Sold... miss it. "88 260E '91 190E 2.6 '89 Volvo 240DL "85 300D
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we are talking about duty cycle numbers for adjusting the fuel air mixture on the fuel distributor. mine was way off (89%)
 

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1992 300E 4-Matic
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I just saw a post from MrLucky about #8 Plugs too. Does anyone have a link to the post about how to adjust the duty cycle?
 

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"Gretchen" my 1986 300E 286000 km+ (RIP) August 2015
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As far as the adjustment is concerned, this was previously posted by member Yal. ( Thanks Yal !!) Do an additional search under idle mixture or fuel distributor adjustment and you should be good to go. This forum is a great source for maintaining and trouble shooting

Its pretty simple. Now it may not be the cause of your problem but its a good start. What you need however is a multimeter from sears that reads duty cycle as a %. Real cheap cost about $30-40, and invaluable Sears.com 482139000. Then you need a set of allen keys, I believe the adjustment nut is #3mm allen size but I am not sure, I just bought a set of them. Take of your air cleaner and you'll see a "steel" tower next to the fuel distributor. The adjustment nut is located inside at the bottom of that tower. Now you have to locate the x11 connector on the driver side fire wall. Its basically a round socket. It looks like something should be plugged into it. Its usually covered with a plastic screw cap.
With the car running and warmed up and your mutimeter set to duty cycle stick the positive terminal into the number 3 hole of the x11 connector and ground the negative terminal. I usually stick the negative on a strut support bolt next to the driver side hood hinge.
Then watch the duty cycle. If its not swinging back and forth make sure you selected % by pressing one of the selectors at the top of the multimeter (took me forever to figure this out).
The duty cycle should fluctuate around 50%, if it doesn't you have to adjust the screw at the bottom of the tower until it does. If I remember correctly clockwise brings it up and anti clockwise vice versa. Adjust by small increments and wait 10 seconds each time. The screw is spring loaded and so you have to depress it a little to get it to engage before turning. If you depress it to far the car will cut off.
Thats it.
It could turn out that all you need is a fuel filter change

If you do this let me know what you find. You can check the same thing from the EHA which is a little balck box at the back of the fuel distributer but you need a test harness for this.
 

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'84 300D/ dakota benz trk. Sold... miss it. "88 260E '91 190E 2.6 '89 Volvo 240DL "85 300D
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GHM, good post. only thing i saw that needs correction is the allen size. the tool needed for adj. is a 3 MM allen wrench. thanks
 

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I suppose that this mixture adjustment routine is for cars without a catalytic converter and Lambda sensor? (It's the function of the Lambda sensor to provide the feedback for automatic, continuous adjustment.)
 

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Depends on the day!
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Lambda (CIS E) Cars still need fiddling. I like to set mine w/ a stand alone A/F meter and 5 wire O2.. The duty cycle off of a 3 wire is rough at best.

One mod you can do is to switch to a 4 wire and run the additional ground to the negative terminal on your battery..decreases response time.

I usually find that the CO as well as the EHA needs tweaking to get the mixture picture perfect across the board (CO only effects 2500RPM and below).

Jonathan
 
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