Q: I have a 1997 Mazda Etude 160e, which has given me excellent service since I bought it in 2005. However, it has an intermittent problem which causes a loss of power every now and then. My mechanic says it's caused by a defective airflow meter.
He also says a new one is very expensive, and he would not recommend a reconditioned one.
How can one confirm that the airflow meter is indeed the problem? - Mogambury
A: The purpose of the airflow sensor (also called the MAF sensor, for Mass Air Flow) is to continuously measure air flowing into the combustion chambers, so that the engine computer can calculate the exact amount of fuel to be injected to achieve the optimal air/fuel ratio.
There are various designs of vairflow sensors, but the best known one is the "hot wire" type.
When an MAF sensor malfunctions, it's sometimes because the wires get dirty.
A faulty MAF sensor will cause symptoms like stalling, hesitation, rough idling and poor fuel economy.
While your mechanic may be correct in his diagnosis, one must confirm beyond any doubt that the MAF sensor is to blame. Do this by taking the car to a Mazda dealer whose diagnostic equipment needed for the Etude is still working.
A better alternative may be to call in a mobile diagnostics expert.
If the MAF sensor is faulty, you have nothing to lose by unplugging its wiring connector, removing the sensor unit and trying to clean the sensing filament(s). They are fragile - do not apply any force to them.
Spray electrical contact cleaner onto them from a distance of at least 60cm. Air dry before reinstalling, verifying the soundness of electrical connections at the same time.
If replacement of the airflow sensor is unavoidable, you can save some money by buying the unit and fitting it yourself, or asking your mechanic to fit it.
The price from a dealer is roughly R4500.
You may be able to get a Bosch sensor from Diesel-Electric but they will need the part number on the present unit, a 10-digit number which will probably start with 0280 ...
Q: FOR umpteen years, I have checked the water level in my car battery as well as the specific gravity, every month. By doing this, I have felt reasonably sure I would pick up any warnings of an impending demise. However, with a new "high tech" battery, I am told the best I can do is to keep turning the key in faith. - Stu
A: Using a hydrometer to keep tabs on the specific gravity was a reliable way of gauging the condition of a battery. With the new, sealed batteries, this is no longer possible.
There are several ways of testing a sealed battery, but most of them require expensive equipment.
The method that I suggest below might not produce as definite and instant a verdict, but it only requires a multimeter.
Start by performing an open circuit test after the battery has been allowed to "rest" overnight.
Put the probes of the multimeter directly on the battery poles and measure the voltage. A reading over 12.65 volts indicates the battery is fully charged and tells you your charging circuit is in good shape.
But it doesn't tell you whether the battery can produce the heavy current needed to operate the starter motor, while powering up the other electrical systems.
For that you need a load test. Switch on as many of the major current-consuming accessories as possible, without starting the engine.
Keep the multimeter connected across the battery, as you switch these on. The voltage reading will fall but if the battery is healthy, it should stabilise above 11 volt, and may then rebound slowly.
A battery at death's door will drop below nine volt.