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AutoMD ... 10/28/2013

2004 Pontiac Bonneville SE 6 Cyl 3.8L


What is making my car engine rattle and sound like a helicopter when in idle and when accelerating?

Just recently (when the weather turned cold) I have had these problems with my Pontiac Bonneville:
-Car sounds and feels like a helicopter when in idle and when accelerating (in neutral, the car revs without any noticeable difficulty)
-The headlights slightly dim when shifting into reverse or drive, and the battery voltage meter significantly drops when I shift into reverse from park
-The voltage meter fluctuates when in idle more than normal
-I hear a slight screech when accelerating
-The check engine light is on when I am in idle, and it begins to flash when I drive a short distance
I have done the following things to try to remedy the problem, but nothing has worked:
-I have changed the spark plugs
-I have changed the spark plug wires
-I have replaced the air filter
-I have cleaned the MAF sensor
-I have replaced the fuel filter

1 Answer


CVO 10/28/2013

A. Engine rattling, it could come from a loosing catalytic converter shield or a broken motor mount. Use a two feet garden hose as a makeshift mechanic stethoscope, and locate it where the noise comes from.

B. Check the vehicle for fault codes to see if there are any sensors were involved to the malfunction of the engine.

1.Local auto parts stores such as Autozone ( not in California) or Advance Auto parts will scan and retrieve any diagnostic trouble codes ( dtc ) stored in the powertrain control module for free of charge..

2. Amazon.com has the code reader for less than $ 15.68 dollars + shipping
Autel MaxiScan MS300 CAN Diagnostic Scan Tool for OBDII Vehicles

3.Re-post the dtc's in here " answer question " for further assistance.

Note: we need the dtc's to identify the sensor, there are a dozen different sensors to operate the car.

Visit this site and see all the different sensors.



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