Fuel Injectors:

In our last post we shed the light on the importance of the fuel pump in the system that feed the engine the highly flammable liquid responsible for the combustion inside its chambers. However, the fuel is easier to combust in the vapor state than the liquid.

Thus, the fuel injector connecting the fuel rail, containing the fuel provided from the fuel pump, to the combustion chamber is responsible for spraying the fuel on top of the piston creating high amount of fuel vapor easy to ignite.

The injector’s exterior is made of strong lasting plastic with metallic extremities that connect to the fuel rail on one side and the engine head on the other. Both ends are sealed with thick O-rings that keep the fuel pressure from escaping.
Inside the injector, a pintle pushed by the fuel pressure blocks it from flowing into the combustion chamber. When the injector is activated by the ECM command (Usually by a PWM signal), the solenoid inside the injector creates an electromagnetic field that moves the pintle letting the fuel through the spray tip.

Common failures in injectors are:

- Clogged filter: It causes a lack of fuel and reduced flow due to dirt in the system (e.g corrosion from the fuel system).
- Badly closing pintle: The injector leaks fuel inside cylinder due to a deformation in the spring or the pintle.
- Warn out seals: It results in fuel leaking to the outside of the engine, the seals dry up due to time or break because of bad installation or even wrong fuel type.
- Dead/short-circuited solenoid.

The spraying pattern of the injector is very important to the efficiency and quality of the combustion.
Fuel vapor burns much faster than fuel in the liquid state, and it burns best when sprayed on the biggest area possible.
Therefore, for a good combustion, we need a fully atomized fuel equally distributed in the combustion chamber.
The picture below shows how the spraying pattern of an injector may vary.

Injector testing is done on a special tool, where the injector’s efficacy can be tested according to the voltage supply, the injector’s spraying pattern can be closely observed and the injector can be checked for any external or internal leakage.

A dead injector will cause a rough misfire and stalling, while a dying injector will cause a bad air-fuel mixture, an increase in fuel consumption, bad emissions and in an internally leaking case, a flooded engine and fuel-engine oil mixture inside the oil system.

Fuel pump

 
The vehicle’s engine alone is nothing but a big air compressor. It is not until we add the correct amount of fuel to the mix that we will achieve a good combustion able to create enough power to move the car. The only component pumping gasoline to the engine is the fuel pump.

Types of fuel pumps:

Early cars were equipped with mechanical pumps located on the engine block. The most common mechanical pumps are made of a diaphragm and a spring that are pushed by a metallic lever excited by the engine’s camshaft. Therefore, the pumping frequency is proportional to the engine speed in this type of fuel pumps.
Mechanical pumps were used with carburetors and later abandoned in the injector era due to their low output pressure (less than 1 bar).

 

 

New cars have electric fuel pumps, they are mostly located in the fuel tank and able to generate more than 10 times the pressure of a mechanical pump.
This kind of fuel pumps are operated, most commonly, by a 12V two wires connector that feeds the motor’s brushes which provide the electricity needed to rotate the armature that is connected to the impeller. The impeller is responsible to pump the fuel from its holes to the inside of the pump (passing through the armature/rotor chamber) and to the top output neck of the fuel pump.

The newest technology in the market at the moment is brushless fuel pumps which are electrically more efficient.

Electric fuel pump specifications:

Electric fuel pumps datasheets are very important, they indicate the flow and pressure of the fuel vs the voltage and current fed, the electric efficiency (which helps the customer to understand the amount of heat generated as well), type of fuel that is able to handle, and the mechanical valves distribution (One-way valves, check valves…).
These information are critical to understand the amount of fuel delivered to the engine and the reliability of the pump.

The performance of the car is directly affected by the efficiency of the fuel pump. When the fuel pump starts to die, it will consume more current, the impeller will rotate with lower speed (a full rotation will take more than 7 ms), thus it will deliver less fuel than expected.

Causes and symptoms:

A broken fuel pump can be caused by:

·         Dirt and particles in the fuel: (Even small particles from the filter or the sealant might cause damage to the pump.

·         Dry running the pump: The fuel lubricates and cools the pump; a dry run will lead to the destruction of the inner parts of the pump.

·         High voltage and current feed: Burns and overheats electric components which results in short circuits.

·         Time: Like any other component, the fuel pump has a lifespan that varies from a car/brand to another.

·         Incorrect fuel type.

·         Low fuel level: Low fuel level will increase the chances of the fuel pump getting dirt into its system or running dry for a short time in corners

A broken fuel pump will reduce the power and the fuel efficiency of the engine while increasing the vehicle’s emissions. In addition, it might affect the starting time, cause random bangs and stall the vehicle.

Conclusion:

The fuel pump is the main character when looking into the vehicle’s power. It is the only component responsible for delivering fuel to the injectors.
A fuel pump giving up can be diagnosed by a lack of performance, higher fuel consumption and sveral mechanically noticed symptoms like bangs, vehicle stalls and an increase in the starting time.
Numerous causes can kill a fuel pump. Mainly related to the electric voltage fed, to the quality, type and quantity of the fuel that the fuel pump operates usually in.

A fuel pump in general is not a maintenance part, it is changed when it starts to fail, and should survive more than 100 000 miles.

Timing belt and timing chain

A vehicle’s engine is an assembly of numerous parts put together, accomplishing different tasks while staying synchronized to achieve an efficient and smooth result. Dividing those parts into three main engine elements:

·         The Cylinder head: Contains the spark plugs, the camshafts that are responsible of controlling the intake and exhaust valves, and have a direct relation with the fuel injectors. It is the upper part of the engine.

·         The Cylinder block: As the name shows, it contains the cylinders. It forms the middle sector of the engine

·         The Crankcase: carry the crankshaft that rotates around itself to move the piston rods up and down. It constitutes the bottom part of the engine.

*To be noted that the number of cylinder heads depends on the engine’s shape and how many cylinders it has.

Figure 1: The main parts of an internal combustion engine (Military.com, 2019)

To operate the engine, all those components must function with great harmony and high precision. To guarantee this, all those parts are connected with timing chains or belt. An engine with bad timing can cause huge mechanical damages to inner parts such as valves, pistons, roads and even the engine’s body generating major problems such as misfire, lack of power, stalling...

Timing chain vs Timing belt:

The timing chains and belt rotates on the camshaft and crankshaft pulleys. The timing chain is made of metal, used in the first decades of the internal combustion engines; it is located inside the engine and lubricated by the engine oil, lasts for a long time depending on many aspects of the engine.
However, the timing belts are cheaper and quieter than the timing chains. They are made of reinforced rubber, first used in the 1960s, placed outside of the engine, and lasts for a shorter time than timing chains. In general, it is recommended to change the timing belt every 90000 - 120000 Kilometres or every 7 years.

It is important to note that in the recent decade, the manufacturers brought back the timing chains into their engines with noticeable improvements in noise and vibration.

Figure 2 (Left): Internal combustion engine’s timing belt. (Sun Auto Service, 2019)

Figure 3 (Right): An internal combustion engine with timing chains (Sellén, 2019)

                                      

Conclusion:

The timing belt is a softer version of the timing chain that connects and makes sure that all the engine parts are working with high precision and harmony. A timing problem in an engine may causes big damages to its various components. Therefore, it is essential to maintain and change your vehicle’s timing belt/chain according to your vehicle’s service manual.

References:

• Military.com. (2019). Auto Repair: Major Engine Components. [online] Available at: https://www.military.com/off-duty/autos/auto-repair-major-engine-components.html
• Sun Auto Service. (2019). What Is The Difference Between A Timing Belt & A Timing Chain | Sun Auto Service. [online] Available at: https://www.sunautoservice.com/timing-belt-vs-timing-chain/
• Sellén, M. (2019). Timing chain vs. Timing belt: Which one is the best? - Mechanic Base. [online] Mechanic Base. Available at: https://mechanicbase.com/engine/timing-chain-vs-timing-belt-differences/

The air-conditioning system

A decade ago, the air-conditioning (A/C) system was an extra feature in a vehicle just like the heated seats, a full airbag system, the reverse camera and sensors… However, nowadays it has become a necessity because of many aspects, such as the huge increase of cars on the roads causing loads of traffic jams and the amount of jobs requiring a long time driving in the hot weather.

The A/C system consists of numerous parts that differs between automotive brands:

• The compressor: Increases the pressure of the refrigerant in the system.
• The A/C hoses (High and low pressure): Connect all the system’s components to create a closed loop
• The condenser: Cools the refrigerant
• The fans: Blow cold air through the condenser
• The receiver dryer OR The accumulator: Removes the moister from the system
• The thermal expansion valve OR The orifice tube: Regulates the flow of the refrigerant in order to expand it and reduce its pressure.
• The evaporator: Absorbs the heat from the cabin to cool the refrigerant and turn it into gas (You might see ice forming on this component)
• The blower: Blows cold air from the evaporator into the cabin

Figure 1: Air-conditioning system diagram (Did It Myself, 2019)

The system works by changing the pressure of the refrigerant gas which affects its temperature, this pressure-temperature relation is similar to a sprayer can getting colder when spraying for a long period of time. According to Guy-Loussac’s law, pressure and temperature are proportional, hence a low-pressure gas has a low temperature (cold) whereas high pressure gas inflicts a high temperature (hot).

The air coming out of the vents has always the same temperature. The temperature set on the A/C panel (Marked in blue in figure 2) is the desired cabin temperature. Consequently, once the actual temperature of the vehicle’s cabin reaches the desired one, the A/C compressor shuts off.

The recirculation loop button (Indicated in red in figure 2)assure a closed loop air system by preventing any outer air (Mostly hot) coming into the cabin which allows the air-conditioning system to transform the hot air inside your cabin to cold air.
The A/C button switch (Circled in yellow in figure 2) turns on and off the compressor manually.

Figure 2: Air-conditioning panel

Although the manufacturers are developing more efficient A/C systems, it remains the most fuel consuming feature in a vehicle when turned on (an increase of up to 20%), and that’s due to the fact that the compressor’s pulley is rotated by the drive belt that is connected to the crankshaft pulley which adds load on the engine.

Nevertheless, it is possible to reduce this increase of fuel consumption, here some tips:

• Adjust your thermostat settings to a comfortable temperature rather than a cold one.
• Always use re-circulation to cool only the air inside the car
• Open the windows without any A/C at start-up (For few minutes)
• Park your vehicle in the shade or use window shades to reduce the heat inside the car

   References:

• Did It Myself. (2019). Recharging Car Air Conditioning - Did It Myself. [online] Available at: https://did-it-myself.com/recharging-car-air-conditioning/ 
• Completely Firestone. (2019). All About Your Car's A/C System | Firestone Complete Auto Care. [online] Available at: https://blog.firestonecompleteautocare.com/maintenance/everything-you-need-to-know-about-your-cars-ac/
• Nrcan.gc.ca. (2019). Vehicle air conditioning | Natural Resources Canada. [online] Available at: https://www.nrcan.gc.ca/energy/efficiency/energy-efficiency-transportation-and-alternative-fuels/choosing-right-vehicle/tips-buying-fuel-efficient-vehicle/factors-affect-fuel-efficiency/vehicle-air-conditioning/21030 

Who Owns Who In The Automotive Industry

While buying a new part for your vehicle, you might notice that it has multiple car brand logos engraved on it. Or when checking the structure of many systems (Engine, transmission, suspension…) a big similarity is noticed in many vehicles.

This resemblance is due to the fact that numerous brands are owned by one parental brand.
Hence, if you are having a hard time finding the original part for your vehicle, it would be helpful to check the shops that have parts for brands that share the same parent brand of your car. (Checking the manufacturing year of your car and the relations between brands at this year is important, due to the changes that occur during the years.)
However, it is advised to buy the original part that has the same part number as your car, but a plan B never hurts right?

The table below shows various vehicle brands and their respective parent brand in year 2019:

Parent Brand	Brands
Volkswagen	Audi; Bugatti; Bentley; Lamborghini; Porsche; Seat; Skoda; Volkswagen
BMW	BMW; Mini; Rolls Royce
Hyundai	Hyundai; Kia; Genesis
Daimler	Mercedes; Maybach; Smart
Fiat Chrysler Automobiles (FCA)	Alfa Romeo; Abarth; Chrysler; Dodge; Fiat; Jeep; Lancia; Maserati; RAM
Honda	Acura
Toyota	Daihatsu; Lexus; Toyota
General Motors (GM)	Buick; Cadillac; Chevrolet; GMC; Holden; Opel; Vauxhall
Ford	Ford; Lincoln
Renault-Nissan	Dacia; Datsun; Infinity; LADA; Mitsubishi*1 ; Nissan ; Renault ; Samsung
PSA Peugeot Citroen	Citroen ; DS Automobile ; Peugeot
TATA Motors	Daewoo ; Jaguar ; Land Rover ; TATA
Geely	Geely; Volvo
INDEPENDENT BRANDS	Aston Martin; Mazda; McLaren; Saab; Subaru; Suzuki ; Tesla

*Some resources consider Mitsubishi as an independent brand because Renault-Nissan owns approximately 34% of Mitsubishi only.

“Bel tanke” (Fuel consumption test) :

Nowadays, minimizing the fuel consumption is a common goal for all automotive manufacturers, as well as a key feature for any person searching to buy a car. Moreover, a sudden increase in gasoline consumption is a nightmare for any car owner.
In Lebanon, a famous term exists to identify the distance travelled using 20 liters of gasoline known as ‘Bel tanke’.

Many aspects influence the fuel consumption of a vehicle. The outside factors such as the outside temperature, pressure (related to the altitude) and the road characteristics (such as angle of the slope, shape…). Inner factors depend on the driver’s technique (Gear changes for example), and the weight of the passengers and their goods.

Therefore, if you are feeling that your vehicle is consuming fuel more than it should or you are just interested in knowing the amount of gasoline used ‘Bel tanke’ of your car, you can always confirm your doubts by stabilizing as much as possible the aforementioned aspects and by following those simple steps:

1. Go to a fuel station and fully fill your fuel tank.
2. Before leaving the station, reset your trip meter (Check your owner’s manual or check online for ‘ Trip reset’ followed by the brand, sub brand and manufacturing year of your vehicle).
3. Drive your car for a specified distance of your choice.Go to the same fuel station and fully fill your fuel tank again. Note the quantity of gasoline bought and the amount displayed by your Trip meter before leaving.
4. Now divide the distance noted by the gasoline quantity to get the distance travelled per 1 (unit) of gasoline.
5. Finally, a ‘Tanke’ is 20L of gasoline as aforementioned, therefore multiply the last result by 20 to get how much your vehicle is consuming per ‘Tanke’.

N.B: Pay attention to the units. The commonly used ‘Bel tanke’ is usually in Kilometers and Liters.

Motor oil specifications and types

Everyone has heard about motor oil specifications (such as 0W-30, 10W-40, 20W-50... etc.) and motor oil types (synthetic oil, conventional oil… etc.). However, few really understand the meaning behind those terms and the suitable motor oil for their vehicle.

Motor oil specifications:

The motor oil specifications identify the viscosity of the oil and follow the universal form “xx W – yy”.

•  The term ‘W’ stands for winter.
•  The ‘xx’ indicates the viscosity of the oil when the engine is starting in cold weather (Around -17 ˚C). A lower viscosity triggers a smoother start-up in cold areas and provides an easier task for the oil pump.
•  The ‘yy’ refers to the viscosity of the oil when the engine is in ideal working temperatures (Around 100 ˚C). A high viscosity in hot conditions results in a thicker oil that is suitable for hot countries and older engines.

Additionally monograde oils exist (such as SAE 30, SAE 40…) but are no longer used in modern automotive engines.

The table below indicates the suitable oil grades for different temperature ranges:

Oil Grades	Temperature ranges ( in ˚C)
0 W - 30	-35 à 35
5 W - 30	-25 à 35
10 W - 30	-20 à 35
10 W - 40	-20 à 40
15 W - 40	-10 à 40
20 W - 50	0 à 50

Motor oil types:

Motor oil types differ in cost, additives that they contain, and usage from one and another. Four general types of oil exist:

• Full synthetic motor oil:
  This type of oil has 0 impurities due to the extra chemical engineered process that has gone through. Therefore, it is the best for people seeking to achieve the engine’s peak performance. Additionally, it contains many additives that protect the engine against oxidation, high and low temperatures…However, it costs up to four times (4x) the price of a conventional oil.

• Conventional oil:
  The most commonly used type of oil. It has less additives and presents less protection than the other types. However, it does its job to lubricate the engine and it is much cheaper than the other types.

• Synthetic blend oil:
  This blended oil is a mix of both conventional and synthetic oil in addition to some additives. It is becoming extremely popular nowadays because of the similarity in aspects and protections to the synthetic oil while costing much less.

• High mileage motor oil:
  As the name shows, it is made for vehicles with high-mileage (more than 75000 Miles), especially modern cars because of the additives it contains which help reduce and protect from leakage, corrosion and oil burn-off. Money wise, it costs almost the same as the synthetic blend oil.

Conclusion:

Therefore, to pick the suitable oil grade and type for your vehicle:

•  If the car is produced for your country/area, check the owner’s manual.

• If your vehicle is imported, seek assistance from a local expert.
• Check the temperature’s range in the upcoming 5-6 months especially if you are in an area that the temperature flactuate significantly.