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Mercedes W140 500SE, W126 560SEL & W460 300GD
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38 Posts
Discussion Starter #1
Hello from Spain.
I have a 90' 560SEL.
Since I bought it in 2004, always has had like a misfiring at idle, a shaking. I've changed, spark plugs, rotor and cap, ignition wires and coil, inyectors and seals, clean the idle valve, engine mounts and something else that I can't remember, but nothing, still shaking, but only at idle.
The idle speed is perfect, 650 rpm in N or P, and 550 rpm in D or R.
Starts perfect, cold or warm.
A few months from now, I have noticed that when it's in R, the car shakes a lot.

I've search and read a lot here, and in spanish forums, but i didn't find nobody with exactly the same problem.

Now I am renewing all the intake manifold gaskets and vacuum lines and elbows.
Can you help me to change the piston o-ring from the fuel distributor? Or you think is unnecesary?
Now I have all removed, and I think is a good thing to change every posible cause of the problem.

Thanks
 

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1993 300TE, 1995 E320 Wagon
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1,895 Posts
Can you help me to change the piston o-ring from the fuel distributor? Or you think is unnecesary?
Now I have all removed, and I think is a good thing to change every posible cause of the problem.
Definitely change that o-ring-- and get the part from MB, not aftermarket. That goes for ALL of the rubber bits you are changing. If you have aftermarket parts on there, it's just not worth the effort (you're getting into a great deal of labor after all-- the cost difference of the MB parts vs. aftermaket is minimal in comparison). As you are changing all of the o-rings and gaskets, as well as the idle air distribution lines, you should (and I repeat... should...) have a perfect idle. The last issue would be whether your "new" injectors are all good-- one bad/poor one could be the issue. Have them tested while the engine is apart...
 

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'89 420SEL, '93 300E and '07 Hyu Santa Fe
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562 Posts
I'm having same issue as well. I will start will plug wires first and then distributor and cap. Injectors are next on a list. Let us know how it goes for you.
 

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Premium Member
1986 420SEL/1995 E300D/4 BMW’s/2 Vanagon’s
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1,026 Posts
I had that problem and it turned out to be the air distribution lines. You could literally hear them sucking air with the hold open. I replaced mine with units from AHAZ...then I replaced them again 1500 miles later their crap split. Used MB units that time. No idle shaking problems since.
 

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Mercedes W140 500SE, W126 560SEL & W460 300GD
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38 Posts
Discussion Starter #5
Well, now I finished, but the car still shaking, I'm really pissed off with this, and now I have another problem.
When I adjust the mixture, the car go to 850 rpm in N or P, and 550 in D or R.
If I disconect the vacuum line to the EZL ignition module, the revs go OK, 650 in P or N, and 550 in D or R.

Do you know why?
 

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'89 420SEL, '93 300E and '07 Hyu Santa Fe
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562 Posts
I'm having same issue as well. I will start will plug wires first and then distributor and cap. Injectors are next on a list. Let us know how it goes for you.
Well my problem was much simpler....When i changed my plugs, i was not able to put 2 plugs properly. Even though i thought i had them in good they were loose.

Thanks to Dave(ElRojo) for helping me putting those in properly while i was there to get EHA.
Now my car idles just perfect and no shaking. Before i was afraid of stop lights as car will shake a lot when stopped and it will run smooth with high rpm so i knew plug has to be checked. Good it threw one plug just when i was pulling in at dave's place.
 

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1988 560 SEL
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7 Posts
Okay folks. I have a similar problem but another interesting symptom. My car will shake at idle but not badly, just a little bit. Also on hot starts it will start right up but missing on several cylinders (I'm guessing several) for about 1-2 seconds and then will clear right up and go back to the very lightly shakey idle. Any thoughts for an easy fix? I just got the car from my uncle and it was basically sitting for the last 4 or so years (inside a heated garage in beautiful, dry Denver, CO).
 

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2000 ML320
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12 Posts
Areces, did you ever sort through your rough idle issue? I am real interested to hear what the culprit was. I think a lot of people have the same problem and your photo documentation was very good. Just curious what you found out after all that work. By chance, after you had it running, did you check each line at your fuel distributor for fuel? My #6 had very low to no flow at idle. Just crack it open with a wrench while the engine is running. If no fuel comes out, it may be that overpriced fuel distributor. Good luck.
 
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