Friday, September 25, 2009

Questions on Automotive Competency

Attempt to answer the following questions to gauge your knowledge on the general aspects of  automotive repair etc..  (some of the questions are tricky, hence you need to read carefully )

1. Which sensor output is the engine rpm of the car ?

     a. Coolant Temperature Sensor
     b. Wheel Speed sensor
     c. Oxygen sensor
     d. Crank Angle sensor

2. To determine that throttle body cleaning is successful, what must you do ?

    a. Clean the spark plugs and check for proper gap
    b. Use scanner to check the TPS for mV of between 400mV to 1000mV
    c. Compare the basic rpm before and after cleaning of the throttle.
    d. Ensure that the IPS switch is ON when throttle is at idle.

3. When must there be a ‘relearn’ requirement in a typical Efi engine ?

     a. Throttle body cleaning
     b. Replacement of Engine
     c. Removal or replacement of CKP sensor
     d. PCM or ECU replacement

4. Amanda said to Mary, she had advanced the ignition timing of the car (where the rotation of rotor is anti-clockwise), she had

    a. Turn the SAS screw clockwise
    b. With the help of an assistant she advanced by stepping on the accelerator and the assistant turn the MAS screw accordingly.
    c. Turn the distributor body clockwise
    d. Turn the distributor body anti-clockwise
    e. Never turn the distributor body, instead turn the carburetor body

5. Before Donny start the engine for the first time to perform a compression test on a rusty old banger, he did some of the procedures below. Which procedure below is not correct ?

    a. Throttle must be wide open
    b. Remove all the spark plugs
    c. Remove all the spark plugs and immediately connect one of the spark plug hole to the Compression gauge meter.
    d. Never stand in front facing the spark plug holes when starting the engine.
    e. Unplug Distributor 6 pin connector (efi) or remove the distributor wire from the coil or even ground the central electrode of the distributor ( carb engine ).
    f. For convenience connect starter motor ‘S’ terminal with a wire upto and near the battery positive post, ready to start on contact with the +ve battery terminal during compression testing.

6. There are many ways to check and locating short circuits in a vehicle. Which one below is not correct ?

    a. Turn on the ignition, connect a test light to the fuse slot of the suspected circuit with all the switches off and locating downstream to the load beginning with the switch open and then closing the switch followed by disconnecting and connecting the connector to it and disconnecting the relay etc.. and stop at the juncture where the light begins to lit.
    b. Turn on the ignition and connect a Voltmeter to the fuse slot of the suspected circuit with the switch open, relay removed, connectors disconnected and in the order above , close the switch , plug in the relay and connect back the connector in the same order and stop at the jucture where the voltmeter display a reading on the screen.
    c.  Disconnect the negative battery terminal, switch ON the suspected component or device and connect one probe of an Ohmmeter to the load side of the fuse slot and the other probe to ground. A short circuit will reveal when the Ohmmeter register 0 or 0.XX Ohms or near zero Ohms value. A good circuit would have passed through the load and hence register a higher Ohm value as it passes through the load which represents some resistance and hence a couple of Ohms of resistance should be the order of the day.
    d.  Connect a voltmeter between the battery negative terminal and the other probe of the voltmeter to all the intermediate devices like switch, relay, connector, splice to other circuits etc. or at the HARNESS END of the device (do not probe the connector at the equipment side) but do it one at a time beginning from the device that is closest to the battery source or nearest to the point of the source of the voltage right up to the load +ve side but never after the load or the -ve side as this will register a near zero to zero reading.

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