Ask the Mechanic: Why is my Prado fuel thirsty and bouncy?

Hello Onzima, you need to investigate and identify the cause of poor fuel economy. Over-inflated tyres can cause a bounce. There are several factors that contribute to poor fuel economy, bad spark plugs being one of them.

Aged or counterfeit spark plugs will not promptly or efficiently burn the air fuel mixture hence leaving unburnt fuel to waste. New spark plugs ought to come from an authorised Toyota parts outlet or reputable independent spark plugs dealer. The counterfeits look like the real ones but do not deliver good spark.

Other factors that will affect fuel economy are bad fuel injectors, a bad oxygen sensor, a dirty air cleaner, leaking vacuum system or faulty engine management system (computer or sensors). You can improve your car’s fuel economy by fueling with differentiated fuel designed with cleaning additives and friction reducing molecules to enhance fuel economy and performance. Service your engine on time, avoid an aggressive driving style and under inflating your tyres.

Over inflated tyres will cause car handling issues and one of them is a bounce. Over inflating tyres is filling air beyond the manufacturer recommended limit. Car manufacturers determine recommended tyre pressure and sizes depending on the design of the car and its suspension as well as intended purpose. Recommended tyre size and pressure is always displayed at the driver door pillar or the fuel filler flap of many models. Do not rely on the service station tyre pressure attendant to decide what he thinks is right for your car, especially if he is generalising.

WHY HAS MY BATTERY FAILED TO START?

Hello Paul, I own a VW Golf 4. For three weeks now, I have to jump start it every morning. Our family mechanic has replaced the battery and alternator but the problem persists.  Can you help? Annette

Hello Annette, it can be very upsetting when your car battery fails to start in the morning, especially when you are late for work or for a school run. Your car’s battery helps to start the ignition system, which burns fuel and turns your engine. When the engine is running, it turns the alternator which generates electricity to recharge the battery as well as power consumers such as lights, radio, air conditioning and other convenient electrical features. Whereas a bad battery (old or poorly maintained) and a damaged alternator are usually the primary suspects when the battery fails to start, there are other factors that can cause this situation.

These include parasitic drain of the battery due to faulty wiring, damaged control modules or poor installation of accessories such as radio amplifiers and car security devices. These drain the battery because they exceed the small energy demand of the factory fitted clock, immobiliser and radio presets. Occasionally, faulty door switches, radios or accessories that do not power down when you switch off ignition will also drain your battery.

A faulty car charging system can prevent complete charging of the battery. There is need to check the alternator drive belt tension as well as pulley.

Check the alternator circuit and battery terminals for loose connections or corrosion damage, wrong battery capacity and frequent short drives. The car manufacturer recommends a battery capacity depending on the accessories and required cold crank amperage to help start the car when the engine is cold.

If a battery is small it will not hold enough charge for cold cranking. Frequent short battery charges do not allow the car battery to be fully charged. Also, prolonged parking of the car can lead to permanent damage of the battery.

HOW CAN I DETECT COUNTERFEIT ENGINE OIL?

Hello Paul, I sometimes buy affordable engine oil from spare parts shops in Wandegeya. How can I know that the oil they are selling is not counterfeit? What is the effect of using counterfeit oil on my engine?

Deo

Hello Deo, fake or counterfeit engine oil is manufactured to look like genuine oil but does not have the protective and performance enhancing attributes. Counterfeit or fake engine oil is either recycled old engine oil or low grade oil passed off as high grade. Counterfeiters have invested more money in duplicating packaging than the contents of their product, so it is rare for one to be able to identify counterfeit engine oil by observing the poor quality packaging and sealing.

To the casual observer, the counterfeit engine oil will look as clean as the new genuine one. It would take a laboratory analysis and tests to determine counterfeit oil. Therefore, you should consider buying engine oil from an appointed or authorised dealer of the oil brand in question.

Genuine car engine oil is produced by an expensive fractional distillation process before it is blended with additives to protect and improve your engine performance. Good engine oil prevents frictional damage and seizure between fast moving metallic parts, cools the engine by carrying heat away from hot moving parts, cleans sludge, inhibits corrosion, improves sealing and remains in suspension over the drain interval.

Fake engine oil does not provide the above functions. Use of fake or counterfeit engine oil results in engine damage from overheating, warping or frictional metal wear or seizure.

Oil sludge develops and blocks oil passages which will not only lead to poor engine performance but possibly catastrophic damage such as engine knocking due to damage of fast moving engine parts.

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