Using a Scan Tool as a Guide for Car Repairs

Using a Scan Tool as a Guide for Car Repairs:

Use of scan tool for preliminary diagnostic guide

Using a Scan Tool as a Guide for Car Repairs .Today’s cars have various sensor’s most important being coolant temp sensor, oxygen sensor’s, mass air flow sensor, cam and crank position sensors, which constantly give feed back to the engine computer . These sensors work to regulate how the car’s engine runs and to optimize performance. However, sensors loose their optimum values over a period of time and the computer cannot automatically adjust . When this happens, the car’s check engine light will come on to signal trouble to the driver.

The use of a diagnostic scan tool makes retrieving failure codes determine the possible problem . The scanning device will retrieve trouble codes from the computer memory as well pick up those thrown while reading live data with the engine running.

One of the most common components to throw error codes is the oxygen sensor. This device reads and measures the amount of oxygen going through the exhaust system. This tells the computer how efficiently the fuel is being burned and creates a feedback loop that allows the computer to make fuel trims. Fuel trims are adjustments to the amount of fuel being injected into the cylinders for combustion. If the oxygen sensor wave form indicates a higher amount of oxygen in the exhaust, more fuel is added to the combustion cylinder on each cycle. If not enough oxygen is present, the amount of fuel is cut back to balance the combustion.

If this sensor is not functioning properly, the oxygen sensor wave form will make no sense to the computer and it will be unable to compensate and put the correct amount of fuel into the cylinder. This will cause the check engine light to come on and stay on until the error condition is corrected. This usually means replacement of the faulty sensor.

The ideal air fuel ratio for an engine to operate properly, needs to be within 14.7:1. If an engine has a vacuum leak the oxygen sensor will read lean, the computer then adds fuel to compensate. If due to a bad injector or fuel pressure regulator the engine runs rich the oxygen sensor will read rich. The lean codes will be P0171-P0174 and the rich codes P0172-P0175

The diagnostic scan tool can also detect other error conditions while reading live data that could cause the check engine light to come on. Retrieving failure codes is the primary function of this tool. However, some of the more advanced ones on the market allow the mechanic to make changes and reprogram the car’s computer in real time. This helps to streamline the repair process and avoid having to search for the faulty part in a system that contains many different components that could experience mechanical or electrical failure. It also makes it possible to use software in some cases to bypass a problem component until such time as repair is more convenient and keep the car running.

There are a few good small devices such as Blue driver manufactured by Lemur seems to work very good

scan tool

Lemur Blue driver

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