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Vibration when is hot outside
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Baratdur
New User
Jul 15, 2021, 2:45 PM
Post #1 of 5
(1344 views)
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Vibration when is hot outside
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Hello !
I apologize in advance if it is not in the right place in the forum but I do not know what to include my problem. I asked about my problem on several forums, even those devoted to the brand of my car and I was at a few mechanics and I still don't know the answer. My car is a 2013 Mercedes (w204) C300 4matic sport 3.5 v6 . The car under normal conditions drives normally and behaves normally, it is not important whether the ac and the rest of the things are running. The problem begins when the outside temperature exceeds 85F (30C). When the temperature is below 85F (30C) the engine revs when in gear they oscillate around 530 revolutions but when the temperature is high the car keeps revs at about 650 and the car starts to vibrate when it stops at a red light. When I turn off the ac the rpm goes down and stays like that to the moment when i accelerate again rpm goes to 650. The vibrace depends on the situation they are barely perceptible but sometimes aggressive and I can hear deep noise. In the car I replaced the engine mounts and gearbox mount, spark plugs, serpentine belt and tensioner, the fluid in the gearbox (to the one recommended by Mercedes) but I bought the original one, I plan to change in the near future, I replaced the throttle body, both air charge temperature sensors, map sensor, engin oil and engine filter, oil in differentials. The computer does not show any problems, when I went to the mechanic, one said that he did not see the problem, the other began to torture the car in half manual mode, it is an automatic gearbox and stated that it must be a conduction plate with solonoids, despite the fact that I have no symptoms, another mechanic stated It's normal behavior but I know it wasn't like that before so it's probably not normal. I'm sorry for the long post but I don't know where to go to find out what's wrong, maybe someone will be able to say or at least give a hint what else I can look at.
(This post was edited by Baratdur on Jul 15, 2021, 2:46 PM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 15, 2021, 3:29 PM
Post #2 of 5
(1337 views)
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Re: Vibration when is hot outside
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? Not a specialist in these cars but questions and guesses plus what is same for almost anything:
Out of all you said it seems this happens as idle speeds AND YOU ARE SITTING STILL AND OR STOPPED in gear?
Loads of A/C compressing a gas plus being in gear virtually all makes of anything for ages now will self adjust idle speed to stay put at one # - year round any temp when fully warmed up.
This isn't and IMO 530 you meant RPM? It's working harder A/C wise and design of "exotic type" cars may really want same output temps inside for passenger's never to deviate so at 85F or so up how hard it works or ad power to fans??
Both are extra loads you should never notice a drop in RPM.
This should be showing a clear code what fault area or circuit is failing to achieve that for your engine. It needs a place that can read all necessary for this exact car or back to a dealer.
Don't be tossing parts, that doesn't solve issues, rather can bring on chance in doing that you caused yet another problem so concentrate on diagnosis first so it works first try,
T
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Baratdur
New User
Jul 15, 2021, 3:40 PM
Post #3 of 5
(1324 views)
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Re: Vibration when is hot outside
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This happens when the car is in gear when it stops at a red light. If at this time I turn off A/C the rpm drops to normal as they always were when the temperature is below 85. When I still stand and turn on A/C the rpm still remains low. When I press a gas and exceeds 650 rpm it is remain so and do not want to go back to the lower. I will probably have to go to the dealer maybe can actually say something. The whole situation looks like the ecu can't compensate the load but weird that only when it's hot just above 85. One degree below and everything goes back to normal. Thank you very much for the quick answer I never had situation to receive any answer in such a short time thank you very much !!!
(This post was edited by Baratdur on Jul 15, 2021, 3:53 PM)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Jul 15, 2021, 7:20 PM
Post #4 of 5
(1294 views)
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Re: Vibration when is hot outside
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Correct any you are welcome. Idle speeds stay the same in cars is the clue not this. By the 500s (RPM) cars/engines of all sorts stumble some as about to stall of course feel like a problem and it is by itself.
IDK if codes will lead just know they direct you to circuits that show a fault not what part or comprehensive reason. Could be one silly sensor or excessive load out of perimeters of it compensating?
It's a volunteer site to help where and when we can so wish you luck and hit back anytime,
T
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Baratdur
New User
Jul 16, 2021, 1:45 AM
Post #5 of 5
(1279 views)
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Re: Vibration when is hot outside
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Thank you !
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