Ask the Mechanic

Rodney Hood

Hello Rodney, the 2007-2014 Mercedes C class W204 rides on the strong image and solid reputation of its older siblings the W203 and W202. It offers a classier image, updated, more aggressive looks and comfortable seating space with a choice of engines and trims including Classic, Elegance, Avantgarde and AMG.  The C200 Kompressor 16V (supercharged) M271 CGI engine you are looking at delivers 154 horsepower @ 5500rpm. It has a modest acceleration of 0-100kph in 8.6 seconds and will give you a fuel economy of about 13 km/litre on the highway. In city traffic, your fuel economy will hover around 10km/litre depending on your driving style and engine maintenance.

The post 2012 engines were built smaller (1.6L, 4 cylinders in line), more fuel efficient and as fast as their older and bigger siblings. The C180 with Blue efficiency delivers 154 HP but accelerates 0-100 KPH in 8.5 seconds (fuel economy: 17 KM/ Litre) This is largely due to innovations such supercharging, turbo charging, direct or common rail gasoline fuel injection (CGi) and increased gearing (7G-TRONIC)

The W204 Mercedes C class is built to world class standards for impressive handling, safety, comfort and performance. It meets the needs of a daily corporate commuter as well as the transportation needs of a young family of five in the city.

It is limited to use on tarmacked or asphalt road surfaces because of its low ground clearance. However, do not try to raise it with suspension spacers as you will prematurely damage the suspension as well as get driveability and handling issues.

Maintenance can be carried out with the official Mercedes dealer or one of many good independent Mercedes service and repair providers in Uganda. Parts are readily available both with the Mercedes dealership or independent stockists.

MY XTRAIL MISFIRES, LACKS POWER

Hello Paul, I have just acquired a used Nissan XTrail which is misfiring and lacks engine power. What could be the problem?

Steven

Hello Steven, an engine misfire is usually caused by a fault with the ignition or fuel systems. Visit a garage where the ignition coils and spark plugs should be inspected. Worn out spark plugs will not burn fuel while damaged ignition coils will not fire the spark plugs. A magnetic tester can be used to isolate the faulty ignition coil.

An evaluation of the fuel system can quickly be done using a computer diagnostic tool or fuel pressure gauge. This will confirm that ample fuel is supplied for combustion and efficient engine running. I recommend that you note the mileage covered on the odometer. If your Nissan has made 100,000kms, carry out the factory recommended fuel and gearbox filter and oil service. This will help prevent a breakdown of the fuel pump and automatic gearbox.

Use reputable engine oil with anti-sludge and anti-metal sheer molecules. This engine is sensitive to oil and fuel quality and will give you long service if you adhere to the recommendations. Also, check the tyres for expiry or tread condition.

MY TOYOTA GEARBOX HAS ELECTRICAL FAULTS

Recently, I took it for an OBD scan and the fault code P1730 *NC Revolution Sensor Circuit Malfunction* was detected. Immediately after, another scan showed No Fault Data. However, after driving for about 10kms, the fault code returned and the car was not engaging the O/D. The gearbox filter was cleaned, which improved all the gear shifts except gear four.  What could the problem be?

Tusubira

Hello Tusubira, the car diagnostic trouble code P1730 read off your Toyota transmission computer suggests a faulty counter gear speed sensor circuit.  Automatic transmissions such as yours rely on input turbine speed sensor and counter gear speed sensor signals. This information helps the Engine control module to detect the timing of the shifting of gears in order to appropriately control the engine torque and hydraulic pressure in response to the varying driving conditions.

A failure of the counter gear speed sensor will prevent normal shifting of gears and trigger the flashing Over drive (O/D) light.

A good transmission repair technician should investigate for a possible damaged or faulty counter gear speed sensor (CGSS). This must be done after checking the counter gear speed sensor harness, which may have an open or short circuit. A poor electrical connection will prevent smooth running of the CGSS.  A technician should check if prior repairs may have caused a damage or break of the CGSS circuit when the technicians cleaned the transmission filter that improved the performance of your gearbox.

This suggests that your auto transmission is due for a transmission filter and gearbox oil change. Visit Toyota Uganda parts shop for the correct oil and filter. If gear four no-shift condition continues, consider having the number four gear solenoid checked. However, all this must be done after restoring the performance of the CGSS sensor.

WHICH SUV SHOULD I BUY?

Hello Paul, I want to buy either the I.O, CRV or Xtrail. (all used). Of the three, which is most durable and reliable? A RAV4 would be best but I cannot afford it.

Mutungi.

Hello Mutungi, the Mitsubishi IO, Honda CRV and Nissan XTrail are good vehicles with strong credentials if bought in good condition. Mitsubishi IO and Nissan XTrail offer a selectable 4WD system and better ground clearance than the Honda CRV.

They combine the good attributes of a small SUV such as practicality, comfort and tough offroadability. Honda CRV and RAV4 are also comfortable and practical recreation SUVs that can handle well on light off road and gravel road driving. The IO Mitsubishi has the revolutionary fuel saving Gasoline direct injection technology (GDI). Nissan Xtrail is a good all-rounder, which feels robust and settled both on and off road.

All these four SUVs require a good maintenance regime with particular attention on lubrication, fuel and transmission systems. If you are to buy one locally, have a trusted mechanic verify its technical condition and maintenance record before you seal the deal. Their multi valve engines are sensitive to engine oil and fuel quality. Failure to service the transmission oils leads to costly damage.

The Mitsubishi gasoline direct injection (GDi) fuel system, RAV4ii Direct 4 (D4) and multi point fuel injection systems in the Xtrail, CRV and RAV4i are sensitive to fuel quality and will not give you reliable fuel efficient service if they were not looked after well by their previous owners. Of the whole lot, the first and second generation RAV4s have had an easier parts availability and better resale value.

However, this is changing as we get more Xtrails, IOs and CRVs on the road. So, what is critical is the condition of the pre-used car you want to buy.  Do not run away from newer fuel delivery technology; just look after it with efficient engine cleaning fuel and lubricants as well as genuine filters and good maintenance providers.

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