WS4 Fuel Pressure and flow (Petrol only)

Name: Rata Gemmell      

Date: 01/06/2011 

Make: Toyota  

Model: 4A-FE 

Year: 1996

Warning, be careful around raw fuel. It can catch fire! Use appropriate safety precautions. Keep sparks, flame, your body and your clothing away from raw fuel! Know where your fire extinguishers are and use them if necessary.

1.         Locate the two closest fire extinguishers.  (If you have to use it remember to pull the pin, squeeze the handle, and spray at the base of the flame.) Write down where they are: 

 The closest fire extinguisher is located by the main roller door.

2.         If you can, look up Fuel Pressure specifications for the vehicle you are testing. If you can’t look them up, make a guess at the fuel specs you should have and write them down here:

 spec is 265-304 Kpa (2.7-3.1 kgf/cm2, 38-44 psi)

3.         Use eye protection. Optional: Relieve fuel pressure before installing pressure gauge. Or there will be some fuel that sprays at you as you attach the gauge. You can relieve pressure by several methods: 1) To relieve the fuel pressure. Make sure you have a rag to catch the fuel, start the engine. 2) Remove fuel pump (circuit opening) relay or fuse and run the engine until it stops, then crank to check that the engine doesn’t start 3) Use a vacuum gauge on the pressure regulator to lower fuel pressure, or  4) Open a fuel line at some pressure point and catch the fuel in a rag beware there may be lots of fuel.

4.         Attach fuel pressure gauge and notice which scale on the gauge you will be using. Briefly turn key on or start vehicle, then turn it off. Check for fuel leaks.

Are there leaks? No

If there are leaks you must correct them and retest before continuing. If you need help, ask !

5.         Measure the fuel pressure with the key on, engine off. 

Record it here: 300KPA or 44PSI 

6.         Idling: Measure the fuel pressure with the engine idling. Watch the pressure for a couple of minutes.

Record pressure here: 290 kpa or 40psi

7.         Maximum: With the engine idling, use the special tool to clamp the fuel return line. Note: this can only be done for a short period.                                                            

Record pressure here: 600kpa or 87psi 

8.         WOT: With the engine idling, disconnect and plug the vacuum line going to the fuel pressure regulator.

          Record pressure here: 

9.         Residual: Turn off the engine, and watch the fuel pressure for five minutes.

Record your residual or rest pressure here: 300kpa or 44psi

10.         Flow: Hook up proper equipment to read fuel volume if necessary. Record flow gauge results of volume, or how much pumped in 15 seconds: (normal results may be ½ liter in 15 seconds) N/A

11.         Replace vacuum lines. Carefully remove the fuel pressure gauge (beware of fuel spraying into eyes, avoid sparks, etc.) Turn engine key on and off, check for leaks.  Start engine, check for leaks. No leaks? Check here: *

Replace cap over fuel pressure test port. Check when done: Done

Make sure the vehicle is safe and runs fine when done, or tell your instructor.

12.         Explain why it is important to know a vehicle fuel pressure/flow?

It is important to know the fuel pressure flow on a vehicle so you know the fuel injectors are getting the right amount of pressure to inject fuel into the engine to get the best performance and efficiency.

13.         Describe the symptoms a vehicle would give with each case:

Low fuel pressure

If the fuel pressure was low the vehicle would show symptoms of lack of power when going up hill or pulling a load and choppy idling. These symptoms can be caused by a fuel filter that is clogged restricting the flow of fuel,  a fuel pump not working correctly or the fuel pressure regulator may have a weak spring which allows fuel to return to the tank when a low pressure is made. 

Low fuel flow

Low fuel flow would cause a vehicle to idle rough. 


High fuel pressure


Dripping of the injectors


Faulty fuel pressure regulator


Flood the injectors with too much fuel pressure and fuel flow which can cause a rich air/fuel mixture which will cause the engine to rev high at idle. 

WS1 Petrol Fuel Injector Testing

WS1   Petrol Fuel Injector Testing

Make: Toyota Model: 4-AFE Year:

Warning, be careful of diesel common rail injectors. They can have very high voltage; do not touch the electrical connectors. This worksheet is only for petrol engines that have up to 15 volts at the injectors.

1.        Listen to the injectors as the engine is idling. Use stethoscope, vacuum line or long screwdriver. Be careful of moving parts. They should sound like a sharp tap, not a dull thud or nothing.

This is a crude test to see if they are being actuated and are opening.

OK 

Can you get to all the injectors? Yes 

Comments:
The fuel injectors are working ok

2.        Check voltage to the injectors when idling or Key On. This makes sure you have battery voltage to the injectors so they can work.

Record battery voltage: 12.86v

Record voltage at each injector you can get to by back probing. Be careful to not puncture or damage wiring.

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
13.09v	13.21v	13.35v	13.33v			Volts

3.        With engine idling, watch injector firing by using an LED tester or test light (with normal incandescent bulb). Hook up test light and connect tip to pin that has back probed connector to injector -. As the injector is grounded by the ECM to fire, the test light should also be grounded to fire, and will flash.

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
ok	ok	ok	ok			Tick if flashes OK

4.        With engine idling, watch injector firing by using a multi-meter set to read % (duty cycle). Record the readings for each cylinder at idle in the boxes below.

        

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
4.9%	4.9%	4.9%	4.9%			Duty cycle %

5.        With the multi-meter still set to read % (duty cycle), accelerate the engine with short, fast throttle openings (don’t over-rev or damage the engine please), and note in the boxes below the maximum % reading you can get on the multi-meter: note the RPM.

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
30%	31%	32%	31%			Duty cycle %

6.        Set the multi-meter to read Hz, and with the engine idling, record the readings for each cylinder in the boxes below:

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
7Hz	7Hz	7hz	7Hz			Hz

7.        With the multi-meter still set to read Hz, increase the engine RPM (don’t damage the engine), and watch how the Hz changes. Record your highest reading in the boxes below: Take the readings at the same RPM as you used in question 5.

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
30Hz	30Hz	29Hz	30Hz			Hz

Using this formula calculate the pulse width of each injector both at idle and when the engine is revved up

“Pulse width ms= (% Duty cycle/100)/Frequency”

Show your calculations


#1 cyl idle : (4.9% X 100) / 7Hz = 70 ms
#1 cyl revved : (30% X 100) / 30Hz = 100 ms
#2 cyl idle : (4.9% X 100) / 7Hz = 70 ms
#2 cyl revved : (31% X 100) / 30Hz = 103 ms
#3 cyl idle : (4.9% X 100) / 7Hz = 70 ms
#3 cyl revved : (32% X 100) / 29Hz = 110 ms 
#4 cyl idle : (4.9% X 100) / 7Hz = 70 ms
#4 cyl revved : (31% X 100) / 30Hz = 103 ms

Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
70ms	70ms	70ms	70ms			Calculated Time at Idle
Cyl #1	Cyl #2	Cyl #3	Cyl #4	Cyl #5	Cyl #6
100ms	103ms	110ms	103ms			Calculated Time when revved

Give your conclusion on whether this is an acceptable way to test injectors and why?

This is an acceptable way to test the fuel injectors as you do not need an oscilloscope to check the wave patterns you can use this method to calculate how long the injectors are open for and weather this means the fuel injectors are in good condition

Chart of Inputs and Outputs

Chart of Inputs and Outputs

  

Measure the signals with a multimeter, set to the right setting, and record in the boxes.

Coolant Temperature (THW or ECT) DC volts	Cold engine 2.5v	Warmed-up engine 0.403v
Throttle Position Sensor DC volts	Closed throttle 0.404v	Open throttle 3.725v
Crank or RPM sensor AC volts and Hertz	Idle rpm 0.952v / 0.042KHz	2500 rpm 2.183v / 0.082KHz
MAP sensor DC volts	Idle vacuum 1.409v	No vacuum or key on engine off 3.649v
Air Temperature (THA or IAT) DC volts	Cold engine 2.398v	Warmed-up engine 2.089v
Throttle Position Switch (Idle and/or WOT) DC volts	Closed throttle 0v	Open throttle 12.79v
CAM sensor AC volts & Hertz	Idle rpm 104.4mv / 0.134KHz	2500 rpm 176.5mv / 0.246KHz
Fuel Injector Duty cycle %	Idle 5.7%	Acceleration 12.6%
Idle Air Control Duty cycle %	Idle 66.5%	Cranking or 2500 55.7%

ECT Sensor  

The first sensor I tested was the Engine Coolant Temperature (ECT) because it had to be checked while the engine temperature was cold.
The ECT sensor is used by the ECU to determine what the engine temperature is. The ECU uses this information to calculate proper fuel delivery and ignition timing. The ECT sensor is a thermistor type sensor (the electrical resistance of the sensor decreases as the temperature increases). The ECU sends a reference voltage to the sensor usually of 4 volts. As the engine coolant temperature warms up the electrical resistance across the sensor decreases to about 0.2v. The computer then uses this reading to determine the temperature of the engine by reading the voltage across the sensor. If the engine is cold the ECU will be in open loop mode keeping the injector spray time open longer to spray more fuel because when the cylinder walls inside the combustion chamber are cold fuel condensors to the walls and isnt burnt therefore more fuel is injected to combust and get the engine up to opertaing tempertaure of about 45 degree celcius (warm). The ECU will ignore feedback signals from the ECT and o2 sensor until operating temperatures is reached.
How to do test:
We did test using oscilliscopes, when the engine was cold and while warmed up. The engine has to be turned on and running at idle. The black lead of the scope has to be connected to a good earth and the red lead to the engine coolant signal wire from the sensor. (On this engine there is an outboard box to connect the scope probes to and get a signal). The scope has to be set to DC volts by clicking function then scope and then changing its settings to DC volts. The scope then displays a wave form on the screen and voltage reading and time.


Results: 
The results i got when the engine was cold was 2.5 V and 0.4 V when the engine was warm. These results show that the sensor is working ok. A sensor that wasn't working ok would read a high voltage while the engine was warm. 


TPS Sensor


Theory information: 
The TPS Sensor (Throttle Position Sensor) is a sensor used to monitor the position of the throttle. The sensor is usually a Potentiometer, and therefore provides a variable resistance dependent upon the position of the throttle. The sensor is used by the ECU as an input to its control system. The sensor tells the ECU how open or closed the throttle is so the ECU can provide the correct fuel to go with the air into the combustion chamber.


How to test this sensor:
To test this sensor use a multi-meter set to DC Volts. Touch the red probe of the meter to the TPS signal wire and the black probe to a good earth. Turn the Key ON Engine OFF. 


Results:
Closed throttle i got a reading of 0.4v and as I started opening the throttle the voltage starts increasing. Open throttle I got a reading of 3.7v.