Exhaust Popping Sound Will Worsen In Time If Not Repaired

July 17, 2010/Steve Tackett

MOTOR MATTERS ASK THE AUTO DOCTOR BY JUNIOR DAMATO

Dear Doctor: I am the original owner of a 2003 Mercedes-Benz CLK320 coupe with 42,000 miles. Within one year of purchase I heard a popping noise from the exhaust when coming to a stop. A mechanic at the dealership heard the popping noise after driving the car to his home and back to work and said the Mercedes’ New Jersey office claims this is just from the cooling of components and does not require replacement of the catalytic converter. I’m concerned that the 8-year warranty on that part expires soon. Why should I have to endure this unnatural noise on an otherwise fine car? Howard
Dear Howard: A popping sound is an indication of exhaust gases exploding or a baffle defect in the exhaust. I suggest you go back to the dealer for a second opinion from another technician. The car did not make the popping sound when it was new during your first year of ownership and will only get worse in time.
Dear Doctor: I have a 2006 BMW 525i. I’d like to know how to reset the maintenance intervals for oil change, microfilter, and service interval. My 5 Series is currently out-of-warranty with 68,000 miles and my local mechanic does the work on it. He could not reset these items when he performed my last oil change. Is this something that can be done only by the BMW dealer? Joe
Dear Joe: With just a few simple steps you can reset the oil change interval. It is done through the dash cluster. Turn the ignition key “on” without starting the engine. Press and hold the odometer reset button until the triangle appears. Release the button and repeatedly press the odometer-reset button until the “reminder reset” appears. Once you get the reset message, hold the reset button until reset appears. This how-to information is available from both Identifix (www.identifix.com) and Alldata (www.alldata.com). I highly recommend both Web sites for do-it-yourself auto repair instructional information.
Dear Doctor: Nearly one year ago I purchased a 1998 Ford Taurus with 85,000 miles for my teenage daughter. Recently she informed me that car does not always start up. I determined it was the Anti-theft Device, due to the indication that the “theft” light blinks rapidly whenever the no-start condition occurs. When it doesn’t start we can turn the key three times and the car will reset and start. This is annoying. This occurs with the factory key and I tried to reset the system by disconnecting the battery. Any suggestions? Artie
Dear Artie: I researched your problem on the Identifix Web site and found that there are many possibilities on this fault.

1998 Ford Taurus

Has a professional technician checked for any trouble fault codes stored on the computer memory? Many stored codes in the body module will not set the “check engine” light. I recommend you find an expert in your area who has technician-permitted access to Identifix, as well as knowledge of the 1998 Ford Taurus.
Dear Doctor: I own a 2006 Nissan 350Z roadster with the six-speed manual transmission and 45,000 miles. Whenever I drive for an extended period of time (1 hour or more) in hot weather, the clutch does not return to the normal starting position when changing gears. It stays depressed about an inch or more. It does not affect the shifting but it is annoying. What could be the issue and resolution? Walter
Dear Walter: The pressure plate springs are hot and not disengaging fully. I have seen this problem with other vehicles as well. A clutch pedal adjustment will take out some of the freeplay and make a difference for you. If this does not correct the problem, then a full clutch replacement is needed.
Dear Doctor: I own a new 2010 Honda with the four-cylinder engine. When I am stopped with the car idling in drive with my foot on the brake pedal, sometimes the idle flares up and the car will lurch forward. This has happened seven times in 4,500 miles. Honda has looked at the car twice and found nothing. Do you have any ideas? Frank
Dear Frank: There are no Technical Service Bulletins on this type of complaint for 2010 Honda vehicles at this time. For the idle to flare up means the computer is activating the idle control motor. When the air conditioning compressor cycles the computer will command the idle motor to increase the idle speed. For testing purposes, when you have the a/c or defroster on when the problem happens I recommend you switch off the a/c or defroster and determine if this might be a problem source you can take to the service department. — Junior Damato, Motor Matters

Junior Damato is an ASE-certified Master Technician.

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Copyright, Motor Matters, 2010