3. MAF Sensor
• Engines use a mixture of air and fuel to operate. Without either one
of them, the engine’s performance will be affected. To measure the
amount of air that flows into the engine, automotive engineers have
installed mass air flow sensors. These sensors calculate the air
coming in and send the information to the car’s onboard computer,
called the ECU, to analyze.
• The engine computer uses the mass air flow sensor signal to
determine how much fuel to inject.
4. MAF Sensor design
• Common mass air flow sensors have a very simple design. The sensor
has two wires inside, of which one is heated and the other left cold.
• The MAF system measures air through a unique method. It does that
by determining the amount of current needed to keep the heated
wire 200F hot from the cold wire.
• The MAF will change the amount of current that enters the wire and
using this method the amount of air will be either increased or
decrease.
5. Signs of a Bad Mass air flow
(MAF Sensor)
• The most common symptoms from a bad mass air flow sensor are slow
accelerating and reduced engine power. You can also notice a difference
in the fuel economy as the main function of the mass air flow sensor is to
let the engine know how much fuel it should inject.
• 1. Check Engine Light Illuminates
• 2. Lean Idling
• 3. Engine Does Not Start Properly
• 4. Engine Drags
• 5. Delay in Acceleration
• 6. Excessive Fuel Consumption
6. Signs of a Bad Mass air flow
(MAF Sensor)
• If the sensor doesn't measure the air flow correctly, the fuel injection
system won't work properly. Common symptoms include:
- Stalling
- Difficulty starting
- The engine starts and stalls
- Lack of power
- Unstable idle
Because the mass air flow sensor readings are used to calculate the engine
load, the traction control system may stop working and the traction control
warning light might also come on on the dash. For the same reason, the
automatic transmission shifting pattern may also change.
7. •The most common causes of the code P0101 are:
- Dirty, obstructed or faulty mass air flow sensor (MAF)
- Cracked, ripped or disconnected intake boot (snorkel)
- Vacuum leaks (stuck open PCV valve, leaking intake gaskets, etc.)
- Clogged up or improperly installed air filter
- The mass air flow sensor element contaminated by excess oil from an oil-soaked
air filter
- Clogged-up catalytic converter or restricted exhaust
Other possible causes include:
- Dirty throttle body
- Bad or dirty manifold absolute pressure sensor (MAP)
- Electrical problems with the MAF sensor connector or wiring
- Stuck open EGR valve
- Incorrect valve timing
- faulty engine computer (PCM)
8.
9. Cleaning a Dirty Mass Air Flow Sensor
• A lot of times, the problems associated with the Mass Air Flow Sensor
occur due to dirt and debris buildup.
• This particle accumulation over time results in poor performance of
the sensor.
• The MAF sensor should be cleaned and serviced every six months or
whenever you change the engine oil. Moreover, it is a good practice
to clean or change the air filter along with the MAF sensor as well.
10. Testing a Bad MAF Sensor
• If the check engine light illuminates on your dashboard, it is time to
visit the nearest auto-shop and have your car scanned for trouble
codes.
• The mechanic will use a scan tool to check what trouble code is
retrieved. The trouble codes from P0100 to P0104 all indicate that
something is wrong with the mass air flow sensor. The trouble
code P0171 and P0174 are also caused due to a damaged or faulty
mass air flow sensor.
11. checking the mass air flow sensor by using a
voltmeter.
• To test the sensor, connect it to the voltmeter and measure the signal
at different engine speed and compare it with the specific range.
• If your car produces a digital signal, use a scan tool to read the data.
Once you have taken the reading of your sensor, replace it with a new
sensor and check again to notice the difference. If there is a
significant difference, it means the sensor is faulty and should be
changed.
13. Throttle Position Sensor Symptoms (TPS)
• (TPS) is an integral part of the vehicle’s fuel management system as it
determines the right amount of air/fuel mixture ensuring optimal
performance.
• IT transmits data about the position of the throttle to the engine
control module (ECM) and this information helps to determine how
much fuel should be injected to the engine at the right time.
14. Signs of a Bad TPS
• 1. Poor Acceleration
• 2. Idle Surging
• 3. Check Engine Light
• 4. Sudden Surge while Driving at a High Speed
• 5. Problem with Switching Gears
16. Oxygen Sensor (O2)
• The oxygen sensor, which is also known as the lambda sensor, is
situated in the car’s exhaust manifold.
• It measures the amount of oxygen in the gases that leave your car
through the exhaust.
• The O2 sensor acquires data from the gases leaving your engine and
sends the data to the car’s central computer to analyze. The onboard
computer ensures your engine is working in tip-top condition,
therefore if it senses any irregularity in the exiting fumes, it notifies
you via a number of ways.
19. Location of the Oxygen sensor
• There can be multiple oxygen sensors on your vehicle. These sensors
are located in the exhaust stream of your vehicle. One of the sensors
must be located before the catalytic converter installed in the exhaust
manifold.
• Another two or one sensors would be located after the catalytic
converter. This helps to monitor the performance of the catalytic
converter by comparing the before and after readings. These sensors
may have different locations and numbers based on the design of
your vehicle.
21. Intake Air Temperature Sensor(IAT)
• The Intake air temperature sensor or IAT sensor has the core function
of monitoring the temperature of the air that is entering the engine
of your vehicle. This information is very useful for the engine control
unit or ECU for many functions and calculations, such as calculating
the air density for effective ignition timing and fuel efficiency.
• the PCM requires this information in order to stabilize and regulate
the air-fuel ratio for the combustion engine
22. • The principal science behind evaluating these sensed readings is that the hotter
air is lighter than the colder air in density, therefore the cooler air would need
relatively more fuel in order to burn with the fuel that is injected in the engine.
• f the fuel and air mixture ratio is not correct, the vehicle will not perform to its
full capacity and the fuel consumption may also be increased.
• With this information, the computer system of the vehicle automatically
regulates the fuel injection by altering the injection pulse to inject more fuel
when required. it is especially important to maintain the proper air-fuel ratio
during the hot winds of summer as well as the cool nights of winter as the
temperature extremes can greatly affect the performance of your vehicle by
changing the density of the air that is entering the vehicle. It is also very helpful
in maintaining the emission levels of your vehicle.
23. Where is the IAT sensor located?
• The location of the Intake air temperature sensor is an easily arguable
subject due to different locations in a variety of designs. The best way to
locate the IAT sensor in your vehicle if to refer to the service manual that
is provided by your manufacturer.
• The intake temperature sensor is often integrated your mass air flow
sensor!
• The Intake Air Temperature (IAT) sensor of your vehicle is usually
installed in the lefthand side of the intake manifold. It could be on
the throttle body attached right to the intake manifold.
24. Signs of a Bad Intake Air Temperature Sensor
• 1. Drop in Acceleration
• 2. Hard Cold Start Condition
• 3. EGR Valve Affected
• 4. Poor Fuel Economy
25. Diagnostic Trouble Codes Associated with the
IAT
• A damaged Intake Air Temperature Sensor usually triggers two
trouble codes: P0112 or P0113.
• The P0112 code indicates that the IAT sensor is operating at a low
voltage and reporting a temperature of about 300 °F (149 °C).
• The P0113 code is caused by a high circuit voltage and means that the
IAT sensor is reporting a temperature of about -38 °F (-39 °C).
26. P0110 Symptoms
• Check engine light illuminates
• Engine’s performance drops
• Erratic acceleration
• Trouble when starting the car
• Drop in mileage
• Engine backfire
27. Possible Causes
• Faulty IAT sensor
• Dirty or contaminated IAT sensor
• Wiring or connection problem
• Dirty air filter
• Damaged mass air flow sensor
• Short circuit in the wiring
28. Possible Solutions
• Replace faulty IAT sensor
• Service or clean the IAT sensor
• Inspect wiring and repair broken connection
• Replace old air filter
• Inspect and repair mass air flow sensor
• Check resistance of the circuit and take measures to fix the voltage
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