Tracking the root cause of a common problem

It’s true that today’s models require less frequent maintenance and are more reliable on the road. Routine services of the past such as tune ups and air conditioning maintenance will only be done a couple of times over the life of a car.

Let’s look at a common problem and consider the possible causes. This will help you understand how a “simple” repair can take several hours to diagnose.

WHAT YOU NOTICE:
Your car hesitates when you accelerate.
Possible causes your technician must check:

• Low fuel pressure
• Defective fuel pressure regulator
• Restricted, clogged or dirty fuel injectors
• Malfunction of the EGR valve position sensor
• Defective coolant temperature sensor
• Excessive exhaust back pressure
• Carbon build-up in the combustion chamber (which causes detonation, thereby causing the knock sensor to retard ignition timing)
• Faulty bearing in alternator, water pump, power steering pump or any other system (which creates a noise similar to detonation, thereby causing the timing to retard)
• Use of incorrect octane fuel
• Corrosion/erosion of spark plugs or spark plug wires
• Faulty ground connection
• Defective mass airflow sensor (MAF/MAP)
• Faulty ignition module
• Problem with the cam sensor
• Problem with the crankshaft positioning sensor
• Torque converter clutch

If your 1970 Mustang misfired, there were 10 likely causes for the problem. For this year’s model, there are 30 to 40 items to check. And that’s just diagnostic start.

This is where the value of a quality technician becomes apparent. Diagnosing this complaint requires a repair strategy that will be developed based on the technician’s training and experience. He’ll consider all available information about the complaint, type of vehicle, service bulletins and experience and plan the investigation accordingly.

Here are examples of problem descriptions that are detailed and useful to a technician:

• I notice a rattle under the hood when I reach 40mph.
• The car begins to stall when I hear this noise.
• I notice this problem on warm days after the car has been running about 20minutes.
• The car restarts but black smoke blows out of the tailpipe.
• Information to share with technicians
• Are any dashboard warning lights on?
• When did you notice it now? (e.g., time of day, after driving a specific length of time)
• When do you NOT notice the problem?
• What are you doing when you notice the problem (e.g., accelerating, turning left, going over a bump)
• What feels different to you? (e.g., steering is loose, brakes don’t respond immediately, vibration)
• What do you hear? E.g., rattling, backfires, screeching)
• Are there any special circumstances when you notice the problem? (e.g., when the radio is on, when the trunk is full of groceries)
• Do you notice any unusual smells?
• Do you notice any leaks or fluid stains? What color is the fluid? Where do the stains appear?
• Has the car been repaired recently? Have you tried to repair it yourself?
• Is the car using more fluids than normal?
• Do you feel difference in handling?
• Under what driving and weather conditions do you notice problems?
• Does the car pull in one direction or vibrate?
• Do you smell burning rubber? That could mean overheated brakes or clutch.

IMPROVING YOUR “SHOP TALK”
Don’t use technical jargon unless you are absolutely sure what it means-it’s a temptation, but it can cause confusion. These are common terms overheard in repair facilities.

AFTERMARKET: Part not made by the original manufacturer.
BACKFIRE: Gunshot-like sound from the engine or tailpipe.
BOTTOMING: Car scrapes the ground.
BRAKE DRAG: Brakes do not completely release.
BRAKE FADE: Brakes are slow to respond.
BUCKING: Engine stalls, kicks in, and the car lurches.
CRANK: If the car “will not crank” you hear only a clicking sound when you turn the key in the ignition.
CUTS OUT: When an engine “cuts out” it loses power or misfires.
DETONATION: Rapid, rattling combustion, also called knocking.
DIESELING: Engine runs when you turn off the car because fuel continues to burn.
FAST IDLE: Engine runs fast while vehicle is stopped.
MISS, MISFIRE: Engine runs rough or unsteady at idle or speed.
ROUGH IDLE: When vehicle stops, engine vibrates or shakes.
SHIMMY: Side-to-side motion that makes tires and steering wheel shake.
STALL: Engine dies.
SURGE: Vehicle speeds up and slows down with no acceleration or braking by driver.

FINDING A REPAIR FACILITY YOU CAN TRUST.

The best time to check out a repair facility is before you desperately need one. Ideally, bring your car in for minor service, such as an oil change or tire rotation. Take this opportunity to look over the service area, note the equipment used, and talk to service personnel.

Here are some things to look in evaluating a repair shop:

• APPEARANCE
• AMENITIES
• EQUIPMENT
• REPUTATION
• RECOMMENDATIONS
• SPECIALIZATION
• DEALERSHIPS
• WARRANTY

LOOK FOR THE AAR SIGN. (Approved Auto Repair) For 25 years, AAA has helped consumers with their repair needs by inspecting and certifying quality repair facilities. When you see the AAR sign, you know the repair shop has met AAA’s strict standards for training, equipment and customer service.

Some of the content in this article was provided by AAA Auto Club.