Electronically Controlled Suspension Systems 10/02/2010
What is the difference between electronically controlled suspension systems and automatic stability control? And why do you need to know the difference when you're going to buy a new car? First of all these high-tech systems are becoming much more common on new automobiles and even some of the less expensive models include them as standard equipment.  Electronic suspension Although this technology has been on the market for at least a decade systems that are deployed today look much different than the ones that were used just five years ago. I remember when I was working on an early 90s Corvette the driver's complaint was a suspension warning light that was staying on.
This Corvette had a switch mounted in the center console just behind the shifter that allowed the driver to select touring or sport mode. The problem with this Corvette was with the electronically controlled shock absorbers. I remember that the repairs were covered under the factory warranty and that the replacement electronic shocks were a $1000 apiece. This is nice to know if you buy one of these cars used. Add Comment How Ohms law Works 09/21/2010
This week I wanted to talk about ohms law since I mentioned it in last week's post about taking the ASE automotive electrical test. Although you may not use this formula while you are solving automotive electrical problems if you plan on passing the electrical test, understanding the law and its principles can really come in handy.  Electrical Circuit George Ohm is accredited with the term. He was a German mathematics professor and in 1827 wrote a book that included the explanation of how electricity behaved. His thoughts have become the basis for a true understanding of how electricity works. In his book he states that it takes 1 V of electrical pressure to push one amp of electrical current through a 1 ohm resistor. This equation is the basic law of electricity and is known as ohms law. In a practical example a simple electrical circuit can be connected to a voltage source by conductors better known as wiring. ASE automotive electrical test 09/12/2010
It is time for me to take my ASE automotive electrical test again. Every five years we are required to re certify in each individual area. To me the automotive electrical test is one of the more difficult to pass.  25 years of auto repair Even though I have more than 25 years experience and this will be the sixth time I will be taking the test I still find it difficult to pass. The weird part is that when it comes to diagnosis and repair this is one of my strongest areas of the automobile. One reason for this is that the ASE automotive electrical test is very heavy on theory. An understanding of ohms law and other basic electrical and electronic knowledge is required to answer individual test questions that appear on both the re-certification test and the full-blown 55 question test. Turn Signal Flashers 09/02/2010
The turn signal flashers is what is responsible for the blinker light turning on and off. It is also responsible for the speed the light flashes. Often when people have problems with their turn signal they think back to the old days when the most common cause was a bad flasher.  Turn Signal Flasher This device is used in both the hazard warning lights and the turn signal systems. The turn signal flasher itself will look different depending on the year make and model of the vehicle. General Motors vehicles most commonly use an aluminum cylinder type housing to contain the flasher assembly. Ford and some other foreign car manufacturers make their flasher assembly look like a standard relay. In either case they contain a temperature sensitive bimetallic strip and a heating element. This bimetallic strip is connected to one side of a set of contacts. Logical Car Diagnosis 08/24/2010
How logical diagnosis reveals car problems. Most car mechanics will perform a good visual inspection of the suspected problem areas before they formulate a plan of attack. Often this first step will uncover damage that is causing the complaint.  Car Mechanic An example of this is a key wiring harness chewed through by a rat. Small rodents seem to love the taste of wiring. They also find the warm engine compartment a nice place to build a home. These visitors can do a lot of damage in a short period of time. Performing a quick visual inspection may reveal signs of one of these engine compartment pets. Sticks, leaves and branches along with other debris that you would not usually see in an engine compartment such as pieces of bread or trash is a tell tale sign that a rodent has visited. In some cases you may also see tiny pieces of plastic from wiring conduit or colored pieces of insulation mixed into this debris. Engine ping and knock sensors 08/14/2010
The knock sensors purpose is to protect the engine from pre-ignition or engine ping. When this sensor malfunctions or provides a false positive it can cause car problems such as poor performance and bad gas mileage. Let’s review how the knock sensor works and how to test it.  Knock Sensor Sometimes it's not easy to find the root cause of an engine ping problem. When the pinging is coupled with a check engine light it actually makes the diagnosis much easier. With pre-ignition valve clatter in conjunction with a set computer code of P0325 this will lead you in the direction of the knock sensor.
The knock sensor is used to back off ignition timing when the engine is experiencing a knocking or pinging noise. The sensor itself is calibrated to detect the vibrations that are unique to this type of engine condition. When it believes that it hears this noise it sends a command to the power train control module to retard the ignition timing. If the sensor malfunctions it does not always set a check engine light code. It will depend on the year make and model of the vehicle. Ignition engine misfire 08/06/2010
When your engine is running rough or you have a misfire condition the problem can be a fuel system malfunction. But more often than not I personally have found an ignition engine misfire to be more common than one that is related to the fuel system.  Fuel injectors Yes you can have a problem with a fuel injector that is either dirty or leaking. But in my opinion it's just not as common as finding a malfunction in the ignition system. Malfunctions such as a bad spark plug wire or even worn or fowled spark plugs seem to be a more common cause of a cylinder that is not firing correctly. Checking ignition related misfires
Cylinder Head Gasket 07/25/2010
The cylinder head gasket is probably one of the most important sealing components in the engine. One of the telltale signs when this gasket fails is that coolant will mix with the engine oil. When this happens the engine oil will turn to a milky color and a jelly like consistency. Often the more severe the leak the milkier the oil becomes.  Head Bolt Tightening Pattern One of the biggest causes of repeat repairs when a head gasket is replaced would be the procedure for tightening down the bolts was not followed correctly. Head bolts must be tightened in the correct order and to the proper amount of torque. Tightening sequences and specifications are available in your car service manual that will also include the step by step repair procedure for your model. Most cylinder heads are tightened in a sequence that starts in the middle and then moves out towards the ends. The bolts are generally tightened in two or three stages. If the final torque is 100 foot-pounds the bolt may first be tightened to 50 foot pounds all away around before the final specification is reached. Leaking Engine Gaskets 07/18/2010
Sometimes when our cars begin to leak fluid we can blame leaking engine gaskets. Often these fluid leaks begin as seepage and developed into a problem that needs to be addressed for the health of the vehicle and the driveway or parking area.  Engine Gasket Leak For as long as there have been engines there has been a gasket. Over the years the technology has advanced that makes these sealing components more efficient. But every once in a while when they try a new technology sometimes it's actually a step backwards. A quick example of this is just my personal opinion. The latest in Gasket technology sometimes referred to as a composite looks and feels like plastic. An example of a step backwards is in the reliability of the Gasket in the General Motors V6 intake manifold. This part looks like a strip of plastic with embedded rubber seals. Misfire codes and check engine lights 07/08/2010
The check engine light is turned on when an engine misfire is detected because unburned fuel pouring into the exhaust manifold will cause extremely high tailpipe emissions. Also if the situation continues raw fuel entering the catalytic converter can cause internal damage to the catalyst. This will also increase tailpipe emissions and will most likely lead to having to replace the catalytic converter which happens to be a very expensive part on most vehicles. For this reason computers can be very sensitive to engine misfires and illuminate the check engine light even if the problem is intermittent. Misfire monitors Crankshaft Sensor The onboard computer is capable of quite complicated misfire monitoring. The engine control module uses the crankshaft angle measurement to detect this misfire. It's actually quite amazing how it is performed. Click the read more button to see how it works.
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