[W126 Coupe] idle recurring "cough"

[Jay Hirsch]

changed plugs in Oct 2, Bosch
Have not changed wires they test good good  spark
On Nov 19, 2010, at 5:09 PM, Mister McGoo wrote:


> You say you keep cleaning the rotor and changing the rotor and  

> cap... you have not mentioned the ignition wires or plugs which  

> form the balance of the physical ignition system.  Have you changed  

> those?  Are they OEM spec components?

>

> Distributor "out of balance"?  In my experience, shouldn't have any  

> distributor problems, particularly at only 100,000 mi.    -Bellamy

>

> Date: Fri, 19 Nov 2010 12:20:15 -0500

> From: J.Hirsch at mac.com

> To: mbcoupes at mbcoupes.com

> Subject: [W126 Coupe] idle recurring "cough"

>

> On going minor problem since Sept 1

>

> Car has  Bosch  rotor and distributor cap

>

> Bosch factory  rotors.... made in Germany and Spain

>

>

> This is what I did on Sept 2:

>

> ["Rotor was slightly burnt on one side, discolored, darker than  

> rest of copper edge which is “normal.” But what is normal?

> Showed it to a friend who is a very good auto mechanic.

>      He said it looks  “a little more burnt than usual.” Told me to  

> sand down that edge  to get the corrosion off

> Put back dist. cap and with cleaned up rotor, car runs great, at  

> idle and highway

> Got new Bosch cap and rotor and will install later today]

>

> One copper end of the rotor gets discolored...slighty burned or  

> corroded.

> Filed down  copper with 600 grit emory cloth.  Put back and all is  

> fine, which I have done several times before which makes me think  

> distributor is "out of balance

>

> Factory coil and ignition  module.  Car has neve been "fooled with"

>

> Have used my 1990  560 SEC  for a total of maybe 600 miles since  

> Sept 3.  Changed   rotor  and  dist cap at this time.

> Car ran great...again

>

> Went  about 250 miles  after Sept 3 when car started "coughing" at  

> idle

> Oct 4, changed spark plugs and rotor at this time, early   and car  

> ran smooth..again

>

> Have gone about 300 miles  since October., yesterday car started  

> "coughing" at idle and not  running too smooth at speed also

> Took out  rotor earlier today, installed new  rotor,  and  "presto"  

> car is smooth and quick again.

>

> Do you think  the distributor is out of balance and time for  

> replacement?  car  just tuned 100,000 miles

>

> or is there something else that is Mercedes related i am not aware  

> of?  i  think it is just basic  "car problem," dist. getting tired.

>

> Jay H

>

> Had  the same  thing happen on two "gringo" cars of mine several  

> years ago...1973 Eldorado and 1963 Lincoln out of balance distributors

> They were "eating points"  when cars had points.  1973 was  last  

> year for points on  Caddy's

> Would change points, good for  a several  hundred miles and then  

> "coughing and wheezing"

>

> Changed distributors and no more problems

>

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> property of MB Coupes, L.L.C.

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