Are winter tyres okay?

I recently bought a used car from a bond and it came with pretty good looking tyres but I noticed that they are marked “Blizzard winter tyres” with a snow symbol on them. My mechanic says they are okay and a couple of friends drive on such tyres. What is your opinion?
Charles

Winter tyres can be dangerous to drive on in our warm weather. Winter tyres are designed with rubber compounds which are designed to stay soft in subzero temperatures. This gives these tyres good traction on the slippery wet snow terrain. However, the rubber compounds in winter tyres are not designed to adapt to the Ugandan warm temperatures or heat generated in a tyre when you drive fast. So when you drive the winter tyres in the 30 degrees plus temperatures, their soft rubber compounds become softer as you drive faster and on the highway and are likely to fail by bursting or the tread peeling off.

Many Ugandan drivers use these tyres and get away with it driving from home to town in slow traffic. However, I know some friends who have almost lost their lives and written off their cars when they got involved in accidents after their winter tyres failed. That said, car tyre manufacturers have designed and sell all weather mixed tyres which are readily available and will work well in our summer or wet weather. You need to visit the nearest new tyre dealer who will explain the difference between winter tyres and all weather tyres.

I drive a BMW 5 series made in 1997. Whenever I start it in the morning the car shakes and then goes off. Sometimes I have to repeat the process three times to engage the gear with ease. It has no problem with starting during the rest of the day. What could be the problem?
Ahmed

You will need a good BMW technician to inspect and confirm the working condition of the engine coolant temperature sensor (ECT) and the intake air temperature sensor embedded in the Mass Air flow sensor. A computer diagnosis will quickly confirm if the sensors are faulty. These sensors help the engine computer know that it is a cold start whenever you start your BMW in the morning or in the evening after parking the whole day. Cold start fuel enrichment is a situation where the engine computer is pre designed to deliver more fuel hence revving up the engine (to above 1,000 rpms) to allow it warm up before cutting the revs and idling normally (about 800 rpms).

This allows the engine to quickly warm up and reach the normal engine running temperature which is necessary for a steady idle, smooth acceleration and efficient running. The technician should look out for fuel pressure loss either due to leaking fuel hoses, an overdue fuel filter replacement or weak fuel pump. Carry out a precautionary inspection of the spark plugs and air filter as their condition also affects the smooth running of any engine.

Whenever I start my Toyota Ipsum engine in the morning or after it has been parked for a while the engine does not fire immediately. When the engine starts it jerks and idles erratically even if you floor the accelerator. What could be the cause of this?

Your mechanic or a good technician needs to check the Toyota Ipsum’s ignition system. Inspect and confirm that the spark plugs produce a strong spark to burn the fuel delivered. In case your spark plugs are still okay but show the presence of wet unburnt fuel, it will be necessary to confirm that there are no leaking ignition leads (damaged high tension wires).

The combination of a strong spark, sufficient fuel pressure and clean unrestricted air supply are integral for quick engine start, stable idling and good response when accelerating. The mechanic should confirm that the fuel pump works well and the fuel filter replacement is up to date. Your fuel filter must be replaced by 100,000 kilometres. Some used vehicles have had their mileage tampered with prior export to Uganda, so you may need to do a precautionary fuel filter change.

Finally, the technician should clean the throttle potentiometer with a good carburettor cleaner in case its clogged with soot and the throttle valve sticks. Should the symptom persist check the performance of the coolant temperature switch which aids the computer to deliver more fuel for the cold start engine running. A breakdown of this switch disrupts engine cold start function.