[W126 Coupe] rough idle

[Jonathan]

I realize the wires are new, but that doesn't mean they are working 
right.  I've had to rebuild wires new out of the box, thus I suggest 
checking them.

Not so much heat range, but the correct non-resistor plugs are no longer 
available from Bosch and running resistor plugs is verboten according to 
Mercedes service literature.

Have you checked your vacuum off the rear of the intake manifold? Make 
sure its nice and steady? Did you replace all the rubber bits under the 
CIS when you did the heads? 
Who remand the FD?  If it's a python I would be leery of it.

Jonathan

Tim Graney wrote:

> yes I replaced the injectors and yes to regulator and fuel 

> distributor. I removed all the federalized stuff. Wires are new...what 

> heat range of plug would you recommend? Thanks in advance Jonathan.

>

>     -----Original Message-----

>     *From:* mbcoupes-bounces at mbcoupes.com

>     [mailto:mbcoupes-bounces at mbcoupes.com] *On Behalf Of *Jonathan

>     *Sent:* Thursday, August 09, 2007 9:58 AM

>     *To:* Mercedes Coupes Mailing Lists

>     *Subject:* Re: [W126 Coupe] rough idle

>

>     Tim Graney wrote:

>>     Here is a question for all you guru's out there. I have a 1985

>>     500SEC Euro AMG which I have pretty much replaced every top part

>>     on the engine and it still idles rough when it is cold . I

>>     replace all the elements that control the idle. The box, the

>>     valve, the fuel controller, warm up regulator. It starts right up

>>     and idles to around 850 RPM nice and smooth then starts to

>>     stumble a little bit like it is running fat. It runs fine once

>>     you take off but stumbles a bit unitl it reaches operating temp.

>>     As soon as it reaches 80C it smooths out and runs and idles

>>     perfectly at 500RPM. I replaced all the sensors on the motor. The

>>     only two I have not replaced are the two thermo time switches. I

>>     also did the heads and replaced all the hydraulic compensators

>>     and lash caps along with all new valves and springs. I just

>>     cleaned the the surface of the heads about .002 to give a nice

>>     mating surface. All the wires have been replaced. New Cap, New

>>     Rotor. I have adjusted the fuel mixture ad nauseum. I use a

>>     vacuum gauge and a exhaust gas analyzer and like I said it run

>>     tits when warm but crap when cold. Any Ideas?

>>     ------------------------------------------------------------------------

>>

>>     The MB Coupes Website!

>>     W126 SEC Mailing List

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

>     I didn't notice injectors in the above list..

>

>     When you say fuel controller, do you mean the regulator or the

>     fuel distributor?

>

>     What spark plugs are you running?  Did you check the wires to be

>     Sure they're spot on (anything beyond 1.2-1.3 Kohms I consider bad).

>

>     I would go ahead and replace those thermo time switches, they're

>     cheap and easy.

>

>     Has this car been federalized (I'm assuming you are in country). 

>     Sometimes they install O2 sensors and frequency valves and once

>     they fail can lead to issues.

>

>     Jonathan

>

>

>     -- 

>     Blue Ridge Mercedes

>     Offering Enthusiast Service, Restoration and Modification.

>     Providing quality parts to discriminating customers in all parts of the world.

>     Located in the Greater Atlanta area.

>     http://www.blueridgemb.com

>     *Updates weekly*

>

>     1996 S600 Euro "Scharnhorst"

>     1991 560 SEC Full Euro ECE (for sale)

>     1991 560 SEC 226Hp/271ft/lbs (TT conversion IP)

>     1988 300 TE

>     1989 560 SEC AMG (Mech.lifter/radical cam conv.)

>     1986 560 SEL 6.0L 32V AMG

>     1980 280 SE Euro

>     2006 Z4 3.0Si M-Spec

>         

>

>

>

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> ------------------------------------------------------------------------

>

> The MB Coupes Website!

> W126 SEC Mailing List

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



-- 
Blue Ridge Mercedes
Offering Enthusiast Service, Restoration and Modification.
Providing quality parts to discriminating customers in all parts of the world.
Located in the Greater Atlanta area.
http://www.blueridgemb.com
*Updates weekly*

1996 S600 Euro "Scharnhorst"
1991 560 SEC Full Euro ECE (for sale)
1991 560 SEC 226Hp/271ft/lbs (TT conversion IP)
1988 300 TE
1989 560 SEC AMG (Mech.lifter/radical cam conv.)
1986 560 SEL 6.0L 32V AMG
1980 280 SE Euro
2006 Z4 3.0Si M-Spec

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