Why does my car temperature shoot up?

Hi Paul, my Toyota Spacio model 2002’s check engine light goes off and comes back on after some time. The computer diagnosis reports VVTi malfunction. We changed that part but still get the same problem. What should we do next?

Hello, the persistent check engine light and diagnostic trouble code on your car confirms that the VVTi (Variable Valve Timing intelligent) system is not functioning normally. The VVTi system is designed to automatically adjust the lift profile of your Spacio’s intake valves. This ensures a more efficient running for best economy and performance results. The VVTi system relies on the VVTi solenoid to receive and relay information to and from the engine computer in order to actuate the intake valve lift adjustment.
This solenoid could fail as a result of damage from engine oil with sludge or deposits and irregular lubrication service.
During the VVTi solenoid replacement procedure, the qualified technician should ensure that the oil sump, timing case and oil pickup / pump are free of sludge or particles. Examine the timing chain and timing guides for possible wear and ensure that engine valve timing is correctly done as per the timing reference points. That should sort out the problem and another computer diagnosis will confirm no fault.

I drive a Toyota Duet but its fuel consumption has gone up lately and the idling is high despite the recent engine tune up. What can we do?
Brian
Hello Brian, your Toyota Duet is a small hatch back with an economical 1.0 litre engine. If it has suddenly become fuel thirsty there must be a problem.
I would first inspect the condition and settings of the throttle valve which basically regulates air intake into the engine.
It should be cleaned with a suitable throttle cleaner and engine idling speed adjusted to normal idling revs of 800 rpm.
Should there be an indication that the idling settings were prior adjusted due to engine loss of power your technician will need to replace the long life fuel filter and confirm the condition of the spark plugs, air cleaner element as well as oxygen sensor.
That should stop the poor fuel economy problem on your Toyota Duet.

Why your car temperature might rise

Tthe car engine cooling system has important components that must all work well in order to provide effective cooling. For instance, the water pump helps to move the coolant fluid around the engine and back to the radiator where it is cooled.
The thermostat is a temperature actuated thermistor coolant gate valve which allows coolant to flow into the engine or stop flowing to maintain the normal engine operating temperature.
The radiator uses air to help cool down the coolant fluid which flows through it as it is pumped around the engine. The coolant fluid is designed with a lubricant and anti-corrosive chemical ethylene glycol which prevents damage to the water pump and other moving components from seizure or corrosion.

Coolant also has additives which help to transfer heat and raise its boiling point to prevent engine overheating. An irregular spike of engine temperature means that one of these components is malfunctioning or needs servicing.
Ordinarily, the engine radiator fan should run intermittently at different speeds, as the temperature rises above the safe limit or is brought down by the cooling fans.

If it runs fast as soon as you start the engine then there is one of two possible causes or both: the fan switch has failed and has been bypassed by a local car technician who has rigged it to run regardless of changing conditions. This will cost you fuel as well as over cool the engine which leads to poor engine efficiency.
The other possible cause of the engine cooling fan over running is the presence of a faulty component such as the water pump or thermostat which may cause overheating.
On some modern cars, the failure of an electronic water pump or thermostat is detected by a coolant pressure or temperature sensor. These two components and the electric fan switch must be carefully examined. A computer diagnosis should also help to point to an electrical component failure if it is the cause.

How the thermostat works

Your car cooling system
Any liquid-cooled car engine has a small device called the thermostat that sits between the engine and the radiator. The thermostat in most cars is about 2 inches (5 cm) in diameter. Its job is to block the flow of coolant to the radiator until the engine has warmed up.
When the engine is cold, no coolant flows through the engine. Once the engine reaches its operating temperature (generally about 200 degrees F, 95 degrees C), the thermostat opens. By letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions.
The secret of the thermostat lies in the small cylinder located on the engine-side of the device.
This cylinder is filled with a wax that begins to melt at perhaps 180 degrees F (different thermostats open at different temperatures, but 180 F/82 C is a common temperature). A rod connected to the valve presses into this wax. When the wax melts, it expands significantly and pushes the rod out of the cylinder, opening the valve.

Process
How it works The car engine cooling system has important components that must all work well in order to provide effective cooling. For instance, the water pump helps to move the coolant fluid around the engine and back to the radiator where it is cooled.

[email protected]