[W126 Coupe] HELP! Car Salling!!!!!

[David Fatovic]

Are there any vacuum hoses that connect the vacuum
system to the transmission?  I got it to the point
where it wont stall anymore, but it has some bit of a
hard time shifting up.  It will sit in the lower gear
at 3K RPM.  When I lift my foot off the gas it just
keeps gear and slows the car down.


Thanks,

David

--- Dick Spellman <spell.yy at verizon.net> wrote:

> David:
> 
> When you say you cleaned under the throttle plate,
> you were referring to 
> the air volume meter???The plate just under the air
> cleaner?  The 
> throttle body is at the very bottom of that entire
> assembly.  It's the 
> first item bolted to the intake manifold.  If that
> throttle plate does 
> not fully close the TPS will see an 'open' which
> will mean that the idle 
> will sit lower than normal.  The idle may stumble a
> bit where it's lower 
> than prescribed.  If you put your foot on the
> accelerator while in park 
> and bring the rpms to say 650 (normal idle) is the
> engine nice and 
> steady?  If it is, you need to test the TPS and I
> think you'll find it's 
> simply a carbon build-up on the throttle body
> preventing the plate from 
> closing fully and the TPS from reading 'closed'.
> 
> To test for a vacuum leak, remove the air cleaner
> assembly, take a spray 
> bottle filled with water and work the spray a bit at
> a time all around 
> the intake manifold and vacuum lines/valves along
> the driver's fender.  
> If you hear/feel the stumble worsen or get better
> concentrate on that 
> one area to route out the leak.  I do not recommend
> spraying carb 
> cleaner or solvent because it eats at the rubber
> fitments over time.  
> Another way is to take a propane torch (not lit) and
> open the valve and 
> work around the intake to see if the idle smooths
> out at any point.  
> Test each of the injector seals or fuel rails in
> this manner as well.  
> Stay away from the hot exhaust and spark plug wires
> where you can.   
> Jonathan pointed out to me some time back the
> frequent failure of the 
> purge hose that goes into the driver's fender.  
> That's an easy check, 
> just pull the fat short rubber hose and see to see
> if it has a dry loose 
> fit.  Another vacuum leak I found was the headlamp
> elevation vacuum 
> circuit.  On one MB it was the dash dial and on
> another the vac line to 
> the passenger headlamp.  Easy enough to pull the
> lines at the dash just 
> behind the elevation dial and close them off to see
> if that makes a 
> difference.  A Mighty Vac does help if you can get
> your hands on one for 
> some of the line tests like the headlamp vac
> circuit.
> 
> The air slider hoses can dry out and leak.  Keep at
> it and you'll find 
> the problem(s).
> 
>  David Fatovic wrote:
> 
> >It sits towards the middle, closer to the left as
> >looking at it.  
> >
> >I took my lunch break today and pulled the Idle
> >Control Valve and cleaned the shit out of it. 
> Almost
> >litteraly.  I also cleaned under the throttle
> plate. 
> >Now on my way back to the office the car did not
> stall
> >on me once, even when warm.  However, idle did get
> >close to it.  The idle did drop below 500rpm a
> couple
> >times at a light.  It was also rough.
> >
> >So now the question is.  I assume I have a vacuum
> leak
> >somewhere that is messing with the idle a bit.  It
> is
> >also making it rough.  What is the easiest way to
> find
> >a vacuum leak?  I don't have any vacuum test tools.
> 
> >Where are the usual leaks found?  
> >
> >David
> >
> >
> >--- "Shayegan, Richard" <rishayegan at davidson.edu>
> >wrote:
> >
> >  
> >
> >>With the car stopped, engine running, in D, where
> is
> >>your economy gauge? Anything other than pegged at
> >>the best fuel mileage side (i.e. the non-red side,
> >>IIRC the left side) means a vacuum leak.
> >>Richard
> >>
> >>________________________________
> >>
> >>From: mbcoupes-bounces at mbcoupes.com on behalf of
> >>David Fatovic
> >>Sent: Tue 6/6/2006 1:36 PM
> >>To: Mercedes Coupes Mailing Lists
> >>Subject: Re: [W126 Coupe] HELP! Car Salling!!!!!
> >>
> >>
> >>
> >>Would a vacuum issue also cause some sluggishness
> >>going from a standstill to the first part of
> >>accelleration?
> >>
> >>David
> >>
> >>--- Dick Spellman <spell.yy at verizon.net> wrote:
> >>
> >>    
> >>
> >>>Hi David;
> >>>
> >>>Glad to hear you found some improvement on the
> >>>      
> >>>
> >>fuel
> >>    
> >>
> >>>filter change.  Any
> >>>way you can test fuel pressures on the system to
> >>>rule out the pump,
> >>>regulator, etc?
> >>>
> >>>As for the unstable idle...You may well have
> >>>      
> >>>
> >>several
> >>    
> >>
> >>>gremlins occurring
> >>>at once.  It should be relatively easy to test
> the
> >>>throttle position
> >>>sensor (TPS) using a VOHM meter.  If the idle
> >>>position is not showing
> >>>'closed' while the engine is at idle, then you
> >>>      
> >>>
> >>could
> >>    
> >>
> >>>have a carbon
> >>>build-up on the throttle body that needs to be
> >>>cleaned or the TPS itself
> >>>may have failed.
> >>>
> >>>If the TPS shows open when it should show closed,
> >>>just jumper the two
> >>>pins on the harness to fake the 'at idle'
> position
> >>>to see if this
> >>>improves the stability of the rpms at idle.  The
> >>>      
> >>>
> >>TPS
> >>    
> >>
> >>>is 3 pins total. A
> >>>center pin which is 'common' and a pin to either
> >>>side that reflect 'wide
> >>>open throttle' (WOT) or At Idle.  Be sure you
> know
> >>>which is which as you
> >>>proceed with the test.  Then at least you will
> >>>      
> >>>
> >>know
> >>    
> >>
> >>>what to repair
> >>>before going further.  There are a number of
> other
> >>>things that could
> >>>cause that erratic idle as well but, this is one
> >>>that's easy to check
> >>>and rule in or out in making the repairs.
> >>>
> >>>Dick
> >>>
> >>>David Fatovic wrote:
> >>>
> >>>      
> 
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