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S600, 350SL, C300
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I hope someone out there has had the same experience and maybe has an answer.

The V12 engine idles at a lower RPM than the V8 and when the A/C compressor cuts in when the car is idling, it often "shudders" and sometimes will stall. The MIL comes on and the code is P1146 plus the usual P03XX misfire codes. P1146 is the left MAS. I have done several diagnostic runs and both MAS behave perfectly during normal driving, so I don't think that is the problem.

Is there something that "anticipates" the A/C clutch and raises the idle? Any suggestions?
 

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1995 S600 (sold)
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I see a technical bulletin listed in Alldatadiy.com. Seems a bit extreme, but it's a possibility. Somewhere there's also a diode matrix that bumps rpm's up when current draw is sensed. Is that the idle control you're refering to T?
 

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Stalling engine on ac start up.

I hope someone out there has had the same experience and maybe has an answer.

The V12 engine idles at a lower RPM than the V8 and when the A/C compressor cuts in when the car is idling, it often "shudders" and sometimes will stall. The MIL comes on and the code is P1146 plus the usual P03XX misfire codes. P1146 is the left MAS. I have done several diagnostic runs and both MAS behave perfectly during normal driving, so I don't think that is the problem.

Is there something that "anticipates" the A/C clutch and raises the idle? Any suggestions?
I would like to think that this car has a typical idle compensating device in the engine management system. If this is the case, part of it should increase the idle speed by about 250 rpm to compensate for the load. Another way of getting around this is to manually increase the idle speed at the throttle body.
 

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I would like to think that this car has a typical idle compensating device in the engine management system. If this is the case, part of it should increase the idle speed by about 250 rpm to compensate for the load. Another way of getting around this is to manually increase the idle speed at the throttle body.
Your joking right? You cant manually increase idle speed on a car like this? Yes there is a adjustment, but if throttle linkage isnt adjusted correctly,it has adverse affects on trans,asr and generally makes it run like crap. If its having a issue like that its normally the diode matrix in the passenger footwell. YOU NEVER go around things like this on a s600. The pure beauty of this car is to idle 12 cylinders at 600 rpm. What makes the m120 so special. Well and the absolute stupid amount of power and torque!!!!!!!!!!

Always fix the problem, NEVER try to go around it....This aint a escort or a corsica.....
 

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1997 S600 (sold)
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This is a 5 year old thread. How did this get dredged up?

On the other hand, I'm completely unfamiliar with the "diode array matrix" responsible for idle control. More information please, phamilton. Part number or wiring diagram code #?

Brett
 
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