Is the D-4 engine fine?

My friend would like to buy a Toyota Vista Ardeo with a D4 engine off the internet. However, his mechanic is discouraging him on the grounds that the D4 engine is problematic and difficult to maintain. Please give me an opinion on this one.
Sam

It is true that some Toyota vehicles with D4 engines on the Ugandan market such as the Vista Ardeo and Premio are malfunctioning. However, there are many happy owners of vehicles with D4 engines. When a D4 engine breaks down it idles rough, intermittently surges and sometimes stalls suddenly. In almost all situations the poor performance of a D4 engine has something to do with negligence - poor maintenance regime (delayed routine service), use of cheap adulterated or leaded fuel or use of wrong or counterfeit service products such as engine oil, oil and fuel filters.

In some cases it is the failure to use trained technicians with modern tooling like computer diagnostics to identify faulty sensors. We need to appreciate that the push for better engine performance and fuel economy by all vehicle manufacturers including Toyota that has evolved engine technology from simple Electronic Fuel Injection (EFi) to the Direct Injection in four cylinders. Mitsubishi calls it Gasoline Direct Injection (GDI), Mercedes calls it Stratified Charge gasoline injection (CGi) Volkswagen calls it Fuel Stratified Injection (FSI), and Toyota calls it Direct four injection (D4).

This technology is here to stay and uses an engine computer controlled system to electronically synchronise delivery of the fuel and spark in a manner that enhances performance and fuel economy in petrol engines. The D4 engine is a development of the EFI (Electronic Fuel Injection) system where fuel is injected into the inlet manifold to mix with the air prior to entering the combustion chamber. In the D4 engines, fuel is injected under very high pressure into the combustion chamber itself (direct injection) avoiding inefficiencies caused by routing the fuel through the inlet manifold. During the combustion process, air is compressed and at a very precise moment fuel is injected directly into the combustion chamber.

This allows the engine to produce fewer emissions while enhancing performance and fuel economy. Let us take more charge of the maintenance of these vehicles. When you buy them off the internet look critically at the mileage to ascertain whether it is close to 100,000 kms. This is when the major Toyota service B should be done with genuine Toyota parts to replace the in tank fuel filter, long life iridium tipped spark plugs (where applicable) and to check the performance of vital sensors like the intake air temper sensor, oxygen sensor or crank angle sensor. All other major fluid changes such as engine coolant, transmission fluid and brake fluid should be inspected and replaced. The air filter should be monitored and replaced on while good quality recommended engine oil and filters from reputable dealers should be used to protect the sensitive components of the Variable Valve timing intelligent drive train system in the D4 engine. Use fuel (petrol) from established dealers because cheap adulterated fuel contributes to build up of deposits on engine valves and spark plugs which affects the D4 engine performance and fuel economy.

Could you please advise me on the Mazda Premacy made in 2002. I would like to know about it in terms of engine performance, comfort, fuel consumption, servicing in terms of spare parts and also any dealer locally in Kampala. Would you recommend someone to buy Mazda Premacy (petrol)?
David Okello

Mazda Premacy is a five seater compact mini multi-purpose van (MPV). Its competition includes the Toyota Ipsum or Opel Zafira. The Premacy comes with the 1.8 and 2.0 litre petrol or 2.0 litre diesel engines. The popular 1.8 litre engine delivers a reasonable 74 kilowatts (99 horse power) which is unimpressive and uninspiring to the overzealous or impatient driver. However, the Premacy 1.8 litre’s fuel economy of 12 kms per litre of fuel on a 54 litre tank will take you far. Road handling is acceptable for town running and for a patient driver. On the highway, you should not drive too fast as it tends to lean and understeer in corners. The design is modern - not too big and easy to manoeuvre.

However, compared to the other MPVs like Ipsum or Opel Zafira the Premacy is smaller and offers only five seats with limited rear legroom and loading space thanks to Premacy’s meagre dimensions in length (4,295 mm) and width (1,705 mm). This is because the Premacy is built on a Mazda 323 saloon platform. Interior amenities are reasonable with air conditioning, power mirrors and windows with audio CD. There are design glitches like the lack of an automatic gear selector position indicator on the dashboard. This makes the driver glance down at the selector to confirm gear position. Reversing is a nightmare because the rear seat headrests hamper clear rear view. Overall, the maintenance situation is a challenge. Whereas you can find after-market engine oil filters that can carry out oil lube service, other parts are hard to find. You have to import them from Dubai or Japan. Resale value is still low because of lack of spare parts among other issues.