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

[Dick Spellman]

David:

Just confirming that before you topped off the transmission fluid.  You 
warmed up the engine, the car was on level ground, and you sat in the 
car and placed the shift selector in each of the gears for a moment or 
two and back to Park before taking the reading?  If not, check the fluid 
level again after doing the above steps.  When was the last time the 
transmission was serviced?  Was the torque converter fluid drained in 
addition to the main tranny case when the filter was done?  What color 
was the fluid you checked today, was there a burnt smell to it, was it 
foamy?

If you corrected a vacuum problem by replacing the hose, that would 
explain the improved idle.  It could also improve vacuum pressure to 
other devices like the modulator on the transmission.  The modulator 
regulates the interval between shifts so you can smooth out a firm 
shift.  The more you smooth it out the more wear you create on the 
clutch plates and so on because you are extending the amount of time the 
plates are permitted to slip before fully engaging.  This improved 
vacuum may have resulted in the modulator being set way too smooth from 
the previous poor vacuum levels.  Having said that and I am no expert, 
I'd start with the transmission fluid level, service done, etc. before 
digging further.  I would not drive the car until you resolve the 
problem you describe.

Dick

David Fatovic wrote:

>OK, so here is a new twist.  I am starting to feel
>like the cartoon character trying to plug the hole in
>the damn by putting his finger in it.  A new one pops
>up.  I checked the trans fluid level this morning and
>it was right at the low line.  I added a touch to
>bring it within the lines on the dipstick.  But now we
>have a new problem.  I changed one vacuum tube this
>morning, the one going from just in front of the fuse
>box (it connects to a 4 way hose connector) and goes
>to the back of the engine just below the throttle
>linkage.  Now the car seems to idle better (a little
>high) but now when you have the car in gear and
>accelerate from a dead stop, the RPMs go up but the
>tranny is not engaged or does not have gear or
>something.  Once RPMs get to about 1500 then the car
>goes in to gear and the car starts to move.  This to
>me is very strange, almost acting like it has no fluid
>in it and not enough pressure to push the plates of
>the tranny together to drive the car.
>
>Any ideas?
>
>Thanks,
>
>David
>
>--- Dick Spellman <spell.yy at verizon.net> wrote:
>
>  
>
>>Hi David:
>>
>>Yes there is a vacuum hose on the intake manifold
>>that runs down to the 
>>transmission vacuum modulator.  If it's loose or
>>disconnected you will 
>>get a hard (almost like a bang) shift between gears.
>> If you say that 
>>the car is hanging in lower gears too long then I'd
>>start by adjusting 
>>the Bowden cable and check all of your engine
>>regulating linkages for 
>>proper adjustment at the same time.  If you then
>>notice a lag between 
>>shifts I'd work the vacuum modulator (T) adjustment
>>to get the correct 
>>shift firmness.
>>
>>Was this car doing this before as well???  Have you
>>checked the trans 
>>fluid level?  When was the last time the tranny and
>>torque converter 
>>fluids were replaced?
>>
>>Dick
>>
>>David Fatovic wrote:
>>
>>    
>>
>>>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
>>
>>    
>>
>=== message truncated ===
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