I drive a Nissan X-Trail model 2000. I have been with this car for one year and it has been running great.
However, I have observed a reduction in engine power when overdrive is turned off, especially when I’m driving uphill or when I am carrying heavy stuff. Before this problem, whenever I turned the overdrive button off, the car would gain stability and even the engine strength would be felt immediately.
However, nowadays I no longer feel the same strength unless I am driving at 80km per hour. I took the car to a diagnosis machine but nothing wrong was detected. What Can I do?
Hello Justus, as you observed, when you turn off the overdrive facility, your automatic transmission should restrict shifting to lower gears. This is designed to provide sufficient torque and power to climb uphill or carry loads. In the event that your Overdrive (OD) facility fails, the OD light on your dash board should flash intermittently, especially if it’s an electrical or solenoid failure. This can also be a result of a circuit breakdown or intrusion of oil in the OD electrical system.
On the other hand, a drop of transmission oil quality or quantity can affect the performance of the OD system. In this event, the light may not flash and the computer diagnostic tool will not pick up the fault. Ask your mechanic to check the transmission fluid.
Dear Paul, recently a mechanic dismantled my BMW X5 4.4 litre engine to replace the damaged timing chain, guides and oil pump. However, after reassembling it the engine has no power, accelerates with noisy misfire and displays the check engine light. We can’t figure out what to do next. What should I do? Jonathan.
Hello Jonathan, the M62 BMW 4.4 litre V8 engine you have in your X5 has a VANOS (intelligent Variable valve timing system) valve train which uses electronic camshaft adjustment solenoids at the front of the engine. Timing the camshafts and solenoids with the crankshaft requires a skilled technician with a special timing tool kit following a particular procedure.
The symptoms you have mentioned suggest that your mechanics did not get the engine timing right. A computer diagnosis will quickly confirm my remote diagnosis.
Hello Paul, my Toyota Harrier 2.2L 4×4 model 1999 has developed a problem of losing strength, especially when driving uphill. Gear No. 2 tends to be very weak and when it changes to Gear 3, and 4 the car starts shaking which scares me very much. What could be the problem?
Hello, the loss of engine power when you drive uphill requires an inspection of your Harrier’s fuel supply pressure and the engine throttle potentiometer. It would be useful to know whether your car’s mileage has reached 100,000kms.
At this mileage you need to replace the fuel filter. Fuel pressure can be affected by a dirty fuel filter which is located in the tank. A faulty throttle potentiometer will reduce engine power as it restricts air supply to the combustion chamber.
A faulty throttle unit also affects gearbox shift quality as described. Consider having it cleaned with carburetor cleaner. A change of your transmission fluid is recommended, if you haven’t done it.
Many thanks for the aice you render to drivers regarding their car issues. What is the fuel consumption or economy of Toyota Vitz with cc 997, especially on highways and in urban traffic? I am planning to buy one, made in 1996. Peter Paul Maloba
Hello Peter Paul, the official fuel economy statistics for the Toyota Vitz are about 18-20 kilometres per litre (KML) on the highway driving at speeds between 80-100 KMHour.
City traffic drops the fuel economy down to approximately 13 KML. Of course, these statistics can be affected by your driving style, engine tuning and maintenance condition (spark plugs, air cleaner, engine oil etc) condition of tyres and overloading.
Ask the mechanic
By Paul Kaganzi
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SOURCE: Daily Monitor