[W126 Coupe] Low Idle and shut off problems. 1987 560 SEC

[Terry Ratliff]

Dick - I am a member of MB Club of America and as far as I know it does not
include an EPC online subscription. Depending on which EPC site you go to,
one charges a lot of money and one is available for North American cars for
FREE at: http://epc.startekinfo.com/epc/welcome.jsp 

You have to enter your charge card and they hit you with $1 for
verification. I expect they will credit back the $1.

Best Regards,
Terry C. Ratliff
eMail: Terry at MyMBSEC.com  
Web site: http://MyMBSEC.com  


-----Original Message-----
From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com]
On Behalf Of Dick Spellman
Sent: Sunday, December 23, 2007 3:58 PM
To: Mercedes Coupes Mailing Lists
Subject: Re: [W126 Coupe] Low Idle and shut off problems. 1987 560 SEC

Hi Crystal,

It does sound like you need to go over the fuel system, the vacuum 
system, and the electrics.  Fixing as you go whatever is worn or needing 
adjustment.  If you are inclined to do all of this yourself, you need 
the cd manuals plus the free Super Nervig Index that makes the manuals 
easier to navigate and locate things. Then if you are a member of MBClub 
you have free access to EPC on-line so you can see where parts are 
located and how they are interconnected.  If not a member ( I am not) 
just pay the annual fee of $20-30 to access the service as a 
subscriber.  Just plug in your VIN and everything specific top your car 
is at your fingertips.

If on the other hand you just want to get things in good working order 
from a really good indy in LA, I'd look-up Steve Lemberg who runs a shop 
in Van Nuys as I recall.  I do not recommend too many mech's but, he is 
excellent and Jonathan in Atlanta is excellent and also sells MB parts 
plus provides some direction.

Really depends on your appetite for fixing.  You need the manuals and 
EPC to get started.

Vacuum.  Then I'd focus on the vacuum system by eliminating the 
peripheral vacuum sources, plugging the manifold sources off to see if 
you can get improved idle.  There are a number of vacuum connections on 
the air flow meter housing, idle air valve, to check once all other 
feeds are plugged off and not essential to checking the engine.  Then 
add one vac circuit back in at a time to see where additional the leaks 
are.  A $30 Mighty Vac does come in handy for this type of inspection.

Fuel.  The easiest path is to get a set of fuel pressure gauges/hoses 
(about$80) and let the gauges with two hook-ups to the Fuel Distributor 
do all the troubleshooting step by step easily.  Any other method is 
pure guess work and you'll spend more money on replacing parts that may 
or may not solve the problem but, never really get a handle on the true 
issues.  Inspect EHA for leaks, inspect throttle plate for carbon 
build-up. Check cold start valve for operation (careful on this as you 
need a jar and you will be spraying fuel).  Both fuel pumps, filters and 
accumulator (pressure damper) are in the rear under the passenger trunk 
area behind pass axle.  When ordering the filters be sure and order the 
two seals (crush washers) needed per each filter.  Still a messy job.

Electrics. I'd pull a few plugs check their conditions, gaps.  Pull the 
dist. cap inspecting for carbon traces and any fine cracks on the 
towers.  Check for pitting on the rotor tip etc.  If these items look to 
be in tough shape order new ones.  Plug wires if they are 100k or older 
just replace with a Karlynn set which is very good quality.  Other 
sensors and harnesses to check, there are many but, here are a few...TPS 
switch for idle stop circuit, engine temp sensors and harnesses.  OVP 
relay fuses initially.  Then check voltages per manual.

Good luck,

Dick

MS. J wrote:

> First, I have found the forum very very helpful.  But I am still a 

> little confused.  I am having cold start, *_low_* idle and stalling/ 

> shut off problems. 

>  

> I have read the archives re: Ignition control valves, and checking 

> fuel filters, relays and OVP relay.

>  

> I have searched various locations to find out what the various parts 

> look like, but not where to find them in my model.

>  

> When putting the car in reverse it shuts off. I concluded a vacuum 

> leak.  I have linked a few of the vacuum lines that were open and one 

> that is located behind the engine I linked up but not sure if I 

> connected in the right place.   To locate that one,  I had to remove 

> the air filter housing to reach it behind the engine, it  travels down 

> under fire wall area.  That seem to help the low idle a little (still 

> way to low) but not the shut off when in reverse, and from start up in 

> low idle.

>  

> I want to change the fuel filter but haven't located it yet. I am also 

> going to change the spark plugs,  wires and not sure if I need to 

> change distributor. How can I can if it needs replacing? I read that I 

> should check the ignition control valve, but not sure it is located.

>  

> Can someone point me in the right direction?

>  

> Crystal

> 1987 560 SEC

> Los Angeles

>

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