How A Motor Vehicle Undergoes Service At A Service Station ?

Introduction :

Amotor vehicle serviceortune-upis a series of maintenance procedures carried out at a set time interval or after the vehicle has travelled a certain distance. The service intervals are specified by the vehicle manufacturer in a service schedule and some modern cars display the due date for the next service electronically on the instrument panel.

The completed services are usually recorded in a service book which is rubber stamped by the service centre upon completion of each service. A complete service history usually adds to the resale value of a vehicle.

Scheduling :

The actual schedule of car maintenance varies depending on the year, make, and model of a car, its driving conditions and driver behaviour. Car makers recommend the so-called extreme or the ideal service schedule based on impact parameters such as :

• number of trips and distance travelled per trip per day

• extreme hot or cold climate conditions

• mountainous, dusty or de-iced roads

• heavy stop-and-go vs. long-distance cruising

• towing a trailer or other heavy load

Experienced service advisors in dealerships andindependent shopsrecommend schedule intervals, which are often in between the ideal or extreme service schedule. They base it on the driving conditions and behaviour of the car owner or driver.

Maintainance tasks usualy carried out during a Motor Vehicle Service :

1. Change the engine oil.
2. Replace the oil filter
3. Replace the air filter.
4. Replace the fuel filter.
5. Replace the cabin filter.
6. Replace the spark plugs.
7. Tune the engine.
8. Check brake level and refill brake fluid / clutch fluid.
9. Check brake pads / liners, brake discs / drums and replace if worn out.
10. Check level and refill power steering fluid.
11. Grease and Lubricate components.
12. Check condition of the tyres.
13. Check for proper operation of all lights, wipers etc.,
14. Wash the vehicle and clean the interiors.
15. Mechanical parts that may cause the car to cease transmission or prove unsafe for the road are also noted and advised upon.

Emission Test Procedures :

The vehicle emission limits are specified based on a standard test procedure, which includes; A specified vehicle driving or engine operation schedule of varying speeds and loads which represents real life driving/usage pattern of the vehicles and engines. The test schedule of vehicle or engine operation is known as ‘driving cycle’. Use of emission sampling systems and analyzers that operate on the working principles specified in the emission regulations. The new production vehicles and engines are tested for compliance with the emission standards in a government approved laboratory. The USA and particularly the state of California have led the world in developing vehicle emission test methods and in setting the vehicle emission limits. The test cycles used in the USA, Europe and Japan for emission measurement and certification of vehicles/engines for compliance with the standards differ and so also the numerical values of the emission limits. Therefore, direct comparison between standards in different countries is generally not possible.

Units of Emission Limits :

Two types of emission limits are specified in the standards For the light and medium duty vehicles, passenger cars and, two and three wheelers are in terms of mass of pollutant emitted per unit distance travelled i.e., g/km ( g/mile in the USA , 1 g/km = 1.61 g/mile). For heavy duty vehicles and engines test is carried on the engine itself and the limits are specified in terms of mass of pollutant per unit of work done, i.e., g/kW-h or g/bhp-h (1 g/kW-h = 1.34 g/bhp-h) . The test cycle and measurement procedures have been accordingly developed whether test is to be done on a vehicle or on the engine.

Driving Cycles for Light Duty Vehicles :

The emission test driving cycles are composed of a cold start period, idling, moderate acceleration and deceleration, and cruise modes. The test cycle is given in terms of vehicle speed versus time. The light and medium duty vehicles are driven through the prescribed driving cycle on a chassis roller dynamometer. During operation the engine is required to develop road horse power that depends on the vehicle speed for a given vehicle. The road horsepower requirement versus speed data as provided by the vehicle manufacturer or determined by vehicle coast down test is stored into chassis dynamometer controller to simulate the real life road operation of the vehicle. The vehicle weight i.e. inertia needed during transient modes of the driving cycle is simulated by mechanically changing the rotating masses or electronically changing the inertia on the roller dynamometer.