1. Input Sensors/Fuel injection
Engine Performance
Input Sensors/Fuel injection

2. Objectives
Explain the design and function of major EFI components as well as input sensors and actuators

3. Input Sensors
Used to detect a mechanical position, chemical state, or temperature condition and change it into an electrical signal that can be used by the PCM to make decisions
Main objective of engine control system is to control emission levels, fuel consumption, drive ability and durability of a vehicles engine.

4. Mass airflow sensor (MAF)
Measures the amount of air entering the engine
Located on the intake tube going to throttle body

5. Ford mass air sensor

6. MAF can be cleaned with approved cleaner

7. Air Temp Sensor (IAT)
Cold dense air can burn more fuel than the same volume of warm air because it contains more oxygen
Measures intake air temperature and sends electronic signal to computer
The computer uses this input along with air volume input to determine the amount of oxygen entering the engine

8. Manifold absolute pressure (MAP)
Some systems do not use a mass air sensor, this type of system uses a MAP sensor
Measures changes in intake manifold pressure (vacuum)
Closed throttle=high vacuum, low map value
Wide open throttle=low vacuum, high map value

9. Engine Coolant Temperature sensor(ECT)(CTS)
Monitors the engine temperature and signals PCM when the engine needs cold enrichment
Usually located on the cylinder head or intake manifold
Screwed into the water jacket in head or intake
Controls open\closed loop functions of the engine

10. Barometric pressure sensor (BARO)
Alters the air\fuel mixture and timing controls, depending upon the altitude at which the car is being driven
At higher altitudes the air is thinner. Less air means the car needs less fuel. The baro sensor adjusts fuel mixture.

11. Engine position sensors(CMP-CKP)
Cam\Crank sensor
Tell the computer the speed of the engine and when the piston in each cylinder is on the compression stroke
This input is used to set ignition timing and fuel injector timing as well
The CKP sensor is also used to monitor engine speed

12. Knock sensor (KS)
Converts engine knock vibrations into a voltage signal
Screwed into the engine block
Tells the PCM when detonation is occurring and PCM will retard timing as needed
Worn engine bearings that are rattling will also cause timing to be changed

13. Oxygen sensors (EGO) Key sensor in closed loop mode
Input is used by the computer to maintain a balanced air\fuel mixture
Perfectly balanced fuel mixture produces an output of .5 volt
Lean mix .1volt
Rich mix .9 volt
Mounted on exhaust system
# of sensors depends on manufacturer
Can be located before and after catalytic converter

14. Oxygen sensor installed

15. Catalytic converter system and O2’s need to warm up quickly in order to be most effective at reducing emissions. O2 located after catalytic is used to monitor performance of converter.

16. Open loop
ECM calculates air/fuel ratio based on inputs from the coolant and MAF sensors and ignores the other engine inputs
The engine managment system (PCM)will remain in open loop until engine reaches operating temperature
The oxygen sensor also has to get hot enough to operate properly
Some oxygen sensors have a built in heater in order for them to get to operating temperature faster
No feedback to PCM
This type of condition usually happens when engine is cold

17. Closed loop Sensors provide constant feed back to PCM
The PCM makes calculations based on input sensors
PCM tries to maintain a air/fuel mixture at 14.7 to 1
Closed loop occurs when engine is at operating temperature
Benefits-Better idle quality, more power with less fuel, and reduced emissions

18. Throttle position sensor (TPS)
Informs the computer about the rate of throttle opening
volt idle speed
4.5volts WOT
Common symptom of a bad TPS is a stumble or hesitation
Mounted on throttle body

19. Vehicle speed sensor (VSS)
This sensor tells the computer the vehicle’s speed in MPH
Usually mounted on transmission tail shaft or transaxle housing

20. Adaptive strategy PCM can learn from past experience
This feature adjusts for worn or misadjusted sensors and ensures that the engine will operate normally
With adaptive learning, a short period is necessary after the battery has been disconnected
Engine may surge, idle fast or have a loss of power.
Average learning period lasts for five miles of driving

21. What if there is a problem present? Check engine light will come on

22. Questions to ask the customer
When did the light come on?
How is the vehicle running?
Has anybody else worked on it?
These three simple questions could save you a lot of diagnostic time.

23. Test drive!!!!!! Diagnose
Test drive the vehicle and verify the complaint
Look up any TSB’s (Technical service bulletins) on vehicle (especially important when working with emission equipment) some parts have 100,000 mi warranty
Hook up diagnostic tool to test port

24. OBDll test port locations

25. Diagnostic Scanners Many different manufacturers
Prices range from $40-$8000
Least expensive scanner only read codes –no data

26. Example of diagnostic trouble code
P0440 –Evaporative system malfunction-gross leak detected
Solutions
Remove and reinstall the gas cap, clear the code, and test drive and see if the codes come back.
Inspect the EVAP system for cuts/holes in tubes/hoses
Inspect for damaged or disconnected hoses around the Evap purge solenoid
Check and/or replace the sensor
Check and/or replace the purge valve
Have a professional use a smoke machine to detect leaks

27. P0300-Random/Multiple Cylinder Misfire Detected
Faulty spark plugs or wires
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Defective computer

28. Repair
After replacing or repairing faulty component make sure to clear all codes
Test drive vehicle
Pull car back into shop and recheck for codes
If no codes then car is ready