Some Basics of a Vehicle's Drivability
http://www.esmartarticles.com/articles/80648/1/Some-Basics-of-a-Vehicles-Drivability/Page1.html
Everette R. Jamison
When looking for used auto parts and used engines consider the leader in parts, http://Everdrive.com By Everette R. Jamison
Published on March 5th, 2010
When you purchase a used or pre-owned car, truck, or SUV, and order a vehicle history report, you may see an item on the report labeled "drivability" It will often be accompanied by a rating
When you purchase a used or pre-owned car, truck, or SUV, and order a vehicle history report, you may see an item on the report labeled "drivability." It will often be accompanied by a rating. This confuses a lot of people. Most drivers intuitively understand labels such as "4-wheel alignment," "coolant flushed," and "no structural damage." But, few know how to interpret "drivability."
The term actually encompasses an assortment of criteria that measure a car's responsiveness to normal driving conditions. It includes cold starts, "no crank" conditions, hesitation, and similar performance issues.
Below, we'll take a closer look at each of the main areas addressed by a vehicle's drivability rating. You'll find the following information valuable in the event you decide to shop for a pre-owned car.
Does The Engine Crank?
If the engine fails to crank, the culprit is likely the starter or the battery. Starter problems often develop gradually. You may start noticing a slow crank condition or odd sounds coming from the starter. Issues related to the battery can range from a lack of juice to poor connections due to corrosion.
It Cranks, But Fails To Start
If your vehicle's engine cranks, but does not start, the problem involves the spark, fuel delivery, or compression. For example, your ignition system might be malfunctioning; your fuel pump may be failing; you may have a vacuum leak reducing compression. Each of these factors will prevent your car from starting even if the engine manages to turns over.
The Car Stalls Out And Dies
Suppose your engine turns over and your car starts, but it stalls shortly thereafter. This type of situation suggests the ignition system is fine. However, something may be wrong with the fuel. The problem may involve the fuel pump, water-heavy gasoline, or a failing relay.
Engine Hesitates When Accelerating
There are many factors that might contribute to hesitation while accelerating. For example, a failing fuel pump can play a role as can a clogged catalytic converter. The manifold absolute pressure (MAP) sensor may be faulty or the exhaust gas recirculation (EGR) system might be defective. There may also be a vacuum leak impacting compression.
Another problem similar to hesitation is an overall lack of power under load. For instance, while pulling something heavy up a steep incline, it might seem as if your vehicle is running out of gasoline. The potential causes of this issue are the same as those which cause hesitation: obstructed catalytic converter, failing fuel pump, EGR problems, etc.
Misfiring Under Load
If your vehicle begins to misfire when accelerating, the issue will usually involve a vacuum leak. Fortunately, vacuum leaks can often be resolved easily by replacing hoses that have become worn and begun to deteriorate. The challenge is finding the location of the leak.
There are also many other potential causes for a misfire under load. A clogged fuel injector, bad spark plugs, failing ignition coil, and a weak fuel pump can each contribute to the problem.
Temperature Related Drivability Issues
If you notice your vehicle experiences problems only when the temperature is hot, the issue may involve a shorting circuit board. This, in turn, can impact the powertrain control module (PCM), which helps manage spark timing, emissions, oxygen sensors, and other systems.
Your vehicle's drivability encompasses a variety of potential conditions that affect its operation. Each problem, as briefly described above, might be caused by one of several factors. Identifying the culprit is not always easy, especially in cases where multiple failing components may be contributing to a given problem.
If you have experience working under the hood (and own a few special tools), you may be able to diagnose and repair the underlying issues. Otherwise, plan to have a trained mechanic do the job for you.
The term actually encompasses an assortment of criteria that measure a car's responsiveness to normal driving conditions. It includes cold starts, "no crank" conditions, hesitation, and similar performance issues.
Below, we'll take a closer look at each of the main areas addressed by a vehicle's drivability rating. You'll find the following information valuable in the event you decide to shop for a pre-owned car.
Does The Engine Crank?
If the engine fails to crank, the culprit is likely the starter or the battery. Starter problems often develop gradually. You may start noticing a slow crank condition or odd sounds coming from the starter. Issues related to the battery can range from a lack of juice to poor connections due to corrosion.
It Cranks, But Fails To Start
If your vehicle's engine cranks, but does not start, the problem involves the spark, fuel delivery, or compression. For example, your ignition system might be malfunctioning; your fuel pump may be failing; you may have a vacuum leak reducing compression. Each of these factors will prevent your car from starting even if the engine manages to turns over.
The Car Stalls Out And Dies
Suppose your engine turns over and your car starts, but it stalls shortly thereafter. This type of situation suggests the ignition system is fine. However, something may be wrong with the fuel. The problem may involve the fuel pump, water-heavy gasoline, or a failing relay.
Engine Hesitates When Accelerating
There are many factors that might contribute to hesitation while accelerating. For example, a failing fuel pump can play a role as can a clogged catalytic converter. The manifold absolute pressure (MAP) sensor may be faulty or the exhaust gas recirculation (EGR) system might be defective. There may also be a vacuum leak impacting compression.
Another problem similar to hesitation is an overall lack of power under load. For instance, while pulling something heavy up a steep incline, it might seem as if your vehicle is running out of gasoline. The potential causes of this issue are the same as those which cause hesitation: obstructed catalytic converter, failing fuel pump, EGR problems, etc.
Misfiring Under Load
If your vehicle begins to misfire when accelerating, the issue will usually involve a vacuum leak. Fortunately, vacuum leaks can often be resolved easily by replacing hoses that have become worn and begun to deteriorate. The challenge is finding the location of the leak.
There are also many other potential causes for a misfire under load. A clogged fuel injector, bad spark plugs, failing ignition coil, and a weak fuel pump can each contribute to the problem.
Temperature Related Drivability Issues
If you notice your vehicle experiences problems only when the temperature is hot, the issue may involve a shorting circuit board. This, in turn, can impact the powertrain control module (PCM), which helps manage spark timing, emissions, oxygen sensors, and other systems.
Your vehicle's drivability encompasses a variety of potential conditions that affect its operation. Each problem, as briefly described above, might be caused by one of several factors. Identifying the culprit is not always easy, especially in cases where multiple failing components may be contributing to a given problem.
If you have experience working under the hood (and own a few special tools), you may be able to diagnose and repair the underlying issues. Otherwise, plan to have a trained mechanic do the job for you.