Fuel Injection Flashcards
Approx fuel pressure for multi port fuel injection systems is:
a. 15-25 psi b. 25-35 psi c. 35-45 psi d. 45-55 psi
c. 35-45 psi
Throttle body fuel injection systems’ approx. fuel pressure is:
a. 7-15 psi b. 15-25 psi c. 25-35 psi d. 35-45 psi
a. 7-15 psi
Pulse width is determined by what on throttle body injection systems in closed loop?
a. Engine coolant temperature sensor b. Oxygen sensor c. MAP sensor d. Throttle position sensor
b. Oxygen sensor
When an injector circuit is fully grounded, the injector is:
a. Closed b. Open c. Half open d. Half closed
b. Open
What would happen if a coolant temperature sensor has an open?
a. Rich fuel mixture b. Lean fuel mixture c. Stoichiometric fuel mixture d. Oxygen sensor controlled
a. Rich fuel mixture
What is the first step to repair a fuel injection problem?
a. Use a scan tool b. Visual inspection c. Verify complaint d. Drive the vehicle into the work shop
c. Verify complaint
What is the fuel pressure for direct fuel injection systems?
a. 25-30 psi b. 30-35 psi c. 40-45 psi d. 50 or more psi
d. 50 or more psi
What is a hot wire used to measure?
a. Liquids b. Air flow c. Friction d. Pressure
b. Air flow
A TPS are most commonly (blank) type sensors:
a. Thermistor b. Potentiometer c. Piezoelectric device d. Resister
b. Potentiometer
The PCM will adjust the idle air control valve based on the:
a. Engine RPM b. Engine load c. Vehicle speed d. All of the above
d. All of the above
As the manifold pressure on an engine rises, the output voltage on a variable resistance MAP sensor will:
a. Increase b. Decrease c. Stay the same d. No difference
a. Increase
A throttle body injection (TBI) system may also be referred to as a/an:
a. Electronic fuel injection system b. Central fuel injection system c. Digital fuel injection system d. All of the above
d. All of the above
An oxygen sensor cycles between 100mv to 800mv. What best describes the operation of the oxygen sensor?
a. Reading rich b. Reading lean c. Reading normal d. Reading stoichiometric
c. Reading normal
An OBD2 equipped vehicle has an exhaust leak at the manifold. What will the oxygen sensor read?
a. Read rich b. Read lean c. Read normal d. Read stoichiometric
b. Read lean
What could be the fault if both the primary and secondary oxygen sensors are within harmony to each other?
a. Bad secondary oxygen sensor b. Both oxygen sensors are normal c. Bad catalytic converter d. Exhaust leak
c. Bad catalytic converter
What are the procedures to check for EGR valve operation?
a. Energize the valve and observe idle quality b. Pressurize the valve and observe idle quality c. Energize the valve and look at the scan tool d. Pressurize the valve and look at the scan tool
a. Energize the valve and observe idle quality
A plugged EGR tube will cause:
a. High CO b. High HC c. High NOx d. High CO2
c. High NOx
An OBD2 vehicle has a check engine light on for an EGR valve failure. After replacing the EGR valve, how do you confirm that EGR operation is ok?
a. Run the vehicle until closed loop b. Run the vehicle in open loop c. Road test vehicle to set drive cycle d. Scan the EGR valve with a scan tool
d. Scan the EGR valve with a scan tool
How is a mass air flow sensor tested with a DVOM?
a. DVOM in series and set to voltage b. DVOM in series and set to amperage c. DVOM in parallel and set to frequency d. DVOM in parallel and set to amperage
c. DVOM in parallel and set to frequency
After replacing a MAF sensor, the vehicle experiences starting and stalling issues. Which of the following could be the cause?
a. Air leaks at the MAF sensor b. Air filter is dirty c. Worn motor mount d. Defective MAF sensor
a. Air leaks at the MAF sensor
A vehicle is towed in for a no start. The tech tests the fuel pressure and finds the fuel pressure rises and drops to zero after key ON. Which of the following can cause this problem?
a. Fuel pump check valve stuck closed b. Fuel pump check valve stuck open c. Fuel pump relay d. ECM
c. Fuel pump relay
Without the use of a scan tool, how can a MIL indicator light be turned off?
a. 5 on/off cycles of the ignition b. 40 drive cycles c. 5 drive cycles d. Key on and moving the gear shifter
b. 40 drive cycles
If the MIL light comes ON during a test drive, what should you do?
a. Stop the vehicle and tow back to the shop b. Drive the vehicle back to the shop and continue with repairs c. Not worry about the light d. Check oil level
b. Drive vehicle back to the shop and continue with repairs
What is the difference between a MIL light ON and Flashing?
a. Nothing b. Flashing MIL is damaging the catalyst c. Transmission problem d. Brake problem
b. Flashing MIL is damaging the catalyst
Which of these codes should be addressed FIRST?
a. P0330 b. P0117 c. P0730 d. P0540
b. P0117
A V6 engine with a zirconium dioxide type oxygen sensor has one defective spark plug. What is the most likely result?
a. High NOx emissions b. Under fueling of all cylinders and cooler engine c. Over fueling of all cylinders d. Shut down of companion top dead cylinders
d. Shut down of companion top dead cylinders
You observe short term fuel trim readings of +28. What does this reading stand for?
a. Over fueling b. Under fueling c. Normal conditions d. Lean mixture
d. Lean mixture
Excessively high fuel pressure can be caused by:
a. Broken vacuum line to the regulator b. Clogged fuel filter c. Kinked pressure line d. Restricted return line
a. Broken vacuum line to the regulator
If an EFI engine has adequate spark and fuel pressure but does not start, what is the most likely cause?
a. TPS signal wire shorted to ground b. TPS signal wire has 5 volt reference c. Crank sensor d. Fuel pump relay failure
a. TPS signal wire shorted to ground
A multi port fuel injection system is over fueling one of the cylinders. What could be the problem?
a. Open in the primary of the injector b. Bad injector ground or bad ground wire to PCM c. PCM issue d. Short in the injector
d. Short in the injector
Engine performance is great and the waste gate hose has fallen off. What would be the result?
a. Waste gate is stuck closed b. Waste gate stuck open c. Restricted exhaust d. Engine miss
a. Waste gate is stuck closed
One cylinder is flooding with fuel. How should we diagnose the fuel injection?
a. Ammeter on injector power wire b. Ohmmeter on injector c. Check ground side of injector and ground wire to the PCM d. Check to see if injector is stuck wide open
Check to see if injector is stuck wide open
While checking a GM EFI vehicle, the secondary coil ignition winding is found to be faulty. How should you diagnose this problem?
a. Ohmmeter on coil post to post b. Secondary post to ground c. Positive side of the coil to the battery d. Negative side of the coil to the battery
b. Secondary post to ground
A plastic or nylon fuel line is ruptured. How should it be repaired?
a. Cut and install a rubber hose b. Replace with a steel line c. Replace the complete fuel line d. Use a compression fitting
c. Replace the complete fuel line
When checking an OBD2 system with a scan tool, how do you diagnose if the catalytic converter is working?
a. Upstream oxygen sensor readings b. Downstream oxygen sensor readings c. Fuel trim d. Open loop
b. Downstream oxygen sensor readings
