A Very Good Car

I remember many years ago while stopping at traffic lights I often wondered to myself how good it would be if the engine can turn itself off. I personally know of people who actually turn their engine off to save fuel! This is false economy as it takes more fuel than you would save when starting the vehicle again.

Well today the hybrid vehicle does it as a matter of course and not only that - it saves energy from braking to release when required and turns the engine off when cruising as well.

Just how good is the Hybrid car when compared to a standard vehicle?

1) Fuel Economy
A well maintained Generation one Prius ( 1997 - 2000 ) still return 20 - 22 Kms to the litre (4.5L/100Kms) This is after clocking up more than 200,000 Kms on the odometer! A standard vehicle would have loss so much compression that it's fuel economy would have deteriorated at least 25% from new.

You can still purchase a good used Generation one Prius for $6000.  If you are currently spending $100 on fuel a week, you could save $2500 a year. This means recouping the cost of your purchase within 3 years at the most. This savings alone should sway thinking people towards purchasing a used hybrid, especially if you have to drive good distances going to and from work.

Generation two Prius (NHW11)  are even more economical and Generation three (NHW20) even better still.

2) Internal Combustion Engine

This engine shuts off when not required. This means that the odometer reading does not represent the actual wear and tear as an engine in a conventional car. My guess is that if we half the odometer reading it would represent the actual wear and tear when compared to a conventional car.

The engine oil in a vehicle that has done 150,000 kms, is still golden a month after an oil change. This means that the piston rings are still intact.

3) Starts every time

One thing I noticed was that the hybrid car will start every time as long as the HEV battery and 12 volt battery are in good working order.
In 12 year old conventional vehicles starting is always questionable as it depends on the state of the 12 volt battery, the starter motor, the alternator, the idling, the timing chain and the distributor. Most of these components are not used in the hybrid car - Less parts to go wrong therefore starts every time.

4) Smooth Quiet and vibration free ride

Although it can best be described as medium saloon, It drives like a large saloon. The combination of the electric engine and the petrol engine contributes to this smooth ride. Being quiet and vibration free adds to the comfort of driving a hybrid.

5) Brakes pads

Regenerative braking recovers the energy from braking which are then stored in the batteries for reuse. This means that the brake pads are not used in normal braking. Most hybrids even at 150,000 Kms still have their original set of brake pads.

6) Spark Plugs

I have personally taken a set of spark plugs out of a car that has done 150,000 Kms. The gap was so large that it stopped firing in one cylinder.

All this goes to show that cost of mechanical maintenance is much lower than a conventional vehicle.

Mass Air Flow meter - Critical equipment in older hybrid vehicles

The ideal fuel mixture entering the combustion chamber is controlled by the onboard computer (ECU).  Depending on the power requirement, the amount of fuel injected is regulated taking into consideration

The number of air molecules entering the chamber ( Its Mass)
The temperature
The Presssure
The Burn ( Oxygen molecules left in the exhaust)

The mass air flow meter provides information on the first 3 items to the ECU.

The Prius uses the hot wire design type air flow meter to determine the air mass flow.  This equipment senses the amount of air flow by measuring the amount of current needed to maintain a constant temperature through very thin platinum wires. 

When air flows pass the wires the wire cools decreasing it's resistance and allows more current to flow through the wires. As more current flow through the wires the wire heats up increasing its resistance which in turn reduces the amount of current flowing through the wires. By measuring the current, the amount of air flowing through the engine is determined.

The  two  platinum wire sensors are set in parallel in the Mass air flow meter. This is important to measure laminar or streamline layered air flows.  If these wires are no longer parallel the laminar flow is disrupted which leads to inaccurate measurements, incorrect fuel mixture, poor engine performance.

 

Notice in this picture that the bottom wire is bent towards the right side. Air flow is no longer laminar, This MAF should be replaced.

 The paradox is that this MAF still works. It may have poor performance in accleration but is not noticeable in street driving. Fuel consumption is still good because working in conunction with the oxygen sensor the fuel mixture is regulated. 

In a normal petrol vehicle one could drive the car happily, putting up with the drop in performance. However in a hybrid vehicle any drop in performance in the ICE is compensated for in the Electric engine. This added demand and completely warp charging regime to the HEV battery quickly cause the battery to fail. 

 

In a hybrid vehicle, especially one where the HEV battery ia already 10 years old, it is imperative that you keep the air flow meter in perfect condition. It is a lot cheaper than reconditioning or replacing the battery.

 It is part of our warranty conditions that you replace the air flow meter after battery reconditioning or the one year warranty will not apply.

Another problem is that dirt and oil can contaminate the hot wires deteriorating it's accuracy. As part of normal service the air flow meter should be cleaned with a commercial Mass Air Flow Meter cleaner product, and the air filter changed.