Buzzing noise?

T

trigun7469

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:
Koup
When I shut my car off and take out the key I can hear a buzzing in the engine bay near the battery. I have owned the car for 3 months now and continue to hear it. I believe it might have something to do with my battery being low and I have had to recharge it twice because it would not start. Any thoughts what might be the problem?

Alternator?
New Battery?
Wiring?
 
Does the sound go away within a few secs? If so, it's normal. I can't recall what it is, but our '10 MZ5 does the same. My '08 MS3 did the same as well.
 
The question is still valid in knowing “what the hell is it”? It’s hard to isolate the noise but to me it sounds like it is coming from the throttle body. Google search consensus says it is the TB doing a calibration – makes sense.
 
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If the humming noise lasts for 20 seconds or so and and then ends with a clicking noise then it's the throttle body sweeping. This happens also to help clear the throttle body of carbon build-up. This wouldn't be a cause of battery drain though.
 
loosenut said:
If the humming noise lasts for 20 seconds or so and and then ends with a clicking noise then it's the throttle body sweeping. This happens also to help clear the throttle body of carbon build-up. This wouldn't be a cause of battery drain though.
Click to expand...

Damn. Never knew what it was. Thanks.
 
loosenut said:
If the humming noise lasts for 20 seconds or so and and then ends with a clicking noise then it's the throttle body sweeping. This happens also to help clear the throttle body of carbon build-up. This wouldn't be a cause of battery drain though.
Click to expand...
This is good info. Can you extrapolate a bit on throttle body “sweeping”? I’m interested in understanding more on the TB but that term doesn’t come up with a match. OR do does sweeping mean calibrating?? As the butterfly plate is completely controlled by the motor, the throttle positioning sensor’s position has to be 100% accurate every time you drive the car.

My initial speculation was that buzzing was due to the electric motor’s delay opening for burn off but I was thinking more in the internal camber (emissions?), not build-up on the TB itself. How does sweeping help clear carbon in the TB? Where in the TB? It would help if I understand “sweeping”. Thanks for input.



COBB did a thorough analysis of a MS3’s TBW system many years back in case anyone else is interested. Very good read and enlightening to know you “think” you have control of the gas pedal but you really only sorta do.

View attachment MS3 TBW Mapping.pdf
 
Wait, does sweeping literally mean “sweeping” (like with a broom motion)? As in the plate is opening/closing (back and forth)? This then means physically clearing the soot build up around the plate and perhaps hinge (since it moves)? If so, would this be an indirect by-product of the TPS calibrating (motor moves to check position, which directly moves the plate) or is that the goal in the first place? If this does sufficiently clean the carbon in the TB, in theory, there is no need to clean the TB, correct?
 
Silentnoise713 said:
Wait, does sweeping literally mean “sweeping” (like with a broom motion)? As in the plate is opening/closing (back and forth)? This then means physically clearing the soot build up around the plate and perhaps hinge (since it moves)? If so, would this be an indirect by-product of the TPS calibrating (motor moves to check position, which directly moves the plate) or is that the goal in the first place? If this does sufficiently clean the carbon in the TB, in theory, there is no need to clean the TB, correct?
Click to expand...

You are correct, the throttle body is doing a full close open close sweep, learning WOT TPS voltage and CT TPS voltage. The PCM wants to know those voltages as they can change due to carbon build-up. I would highly advise cleaning your throttle body as carbon (byproducts) do build up around the bore. For chuckles you can clean the carbon build up and and start the car without disconnecting the battery and you'll see that the idle is really high due to the learned idle throttle position being incorrect. I clean the throttle body with a rag soaked in carb cleaner to avoid getting any liquid past the throttle plate shaft and into the motor/sensor component.
 
With cable driven TBs, I would pull on the cable mechanism to open the plate to clean around and behind it –as much as I could. With these motor driven plates, how do you go about cleaning it? Is it safe to force it open against the motor’s resistance?
 
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http://youtu.be/JPNnHU6PYbo

^^ Mopar cleans up FoMoCo, classic (j/k). Guess you should remove the TB completely for finger safety. Good to know you can manually open the plate and it spring loaded. I wasn't sure if doing that might affect the motor and gears inside that might drive the retrun.
 
I just take the four bolts out and leave the coolant lines installed. Makes it easier to get to the backside. Using your hand to open it won't damage it just don't wedge something in to hold it open.
 
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