[W126 Coupe] Stalling/idling issue

[Tony Damar]

Dick Spellman <spell.yy at verizon.net> wrote:    
If the car appears to have no controlled idle or requires that you 
depress the gas pedal a small amount to start then I'd check your 
throttle position switch (TPS). This is easily tested by placing an 
ohm meter across the center and side terminal on the TPS circuit. You 
can see how this is done by reading 07.3-152 in the MB manual. I am 
just replacing this same switch on an 86 126 chassis 300SE Euro today.
   
  I don't recall having to give it any gas to start, but I will check this also.

If on the other hand you have a rough engine at all speeds, I'd check 
the following and replace as needed:
Bosch W9DC or W9DCO)
Bosch rotor
Bosch cap
   
  Once the car is on the highway, it runs 80-95 mph without a hitch.  Actually, once above 15-25 mph it seems fine.  These items are on my list to replace.  However, it's raining today and on and off for the rest of the week.  I know what I will be working on this weekend!

You say you did the wire set so you should be all set. The vacuum line 
you refer to on the distributor with the faulty check valve is another 
story. If you have the early model 380 distributor it may well have two 
vacuum lines. One for vacuum advance and the other for vacuum retard. 
The check valve(s) must be working for these two vacuum functions to 
work. I'd replace with the original MB specified valve and then check 
the lines and diaphragms using a Mighty Vac.
   
  It's an '85 380SE, so I don't think it's the older style.  I don't recall there being two lines running off the distributor.  I will be replacing the Autozone generic check valve with MB specified valve.  I am thinking about getting new vacuum lines as well.

If after all of the above tests and repairs you still have problems at 
least you will have ruled out most of the common electric issues. I'd 
then move on to testing the fuel system pressures and injection.
   
  Most of the fuel system is new (pump, injectors, seals, etc)... well, 50K miles ago anyway.  

Worse case Tony now that I sit here realizing we know each other, is 
drop by my house and I'll take a look for you anytime this am.

  Thanks for the offer!  Howver, if I left now, it's gonna take me at least 12 hours  to get to the greater Boston area from Raleigh, NC.  
  
Dick
508-641-8477


		
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