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Smog Level 1 Exam: Automotive Diagnostics & Emissions Control, Exams of Motor Vehicle Design

Grossmont - Cuyamaca Community College DistrictMotor Vehicle Design

A series of multiple-choice questions and answers related to smog level 1 exams, focusing on automotive diagnostics and emissions control systems. It covers topics such as engine components, emission control systems, diagnostic procedures, and troubleshooting techniques. A valuable resource for students and professionals seeking to understand and prepare for smog level 1 exams.

Typology: Exams

2023/2024

Available from 12/17/2024

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Smog Level 1 Exam With 100% Correct
Answers 2024/25
3) There is a short to ground between the ground side of the MIL and the PCM - Correct
Answer-During bulb check, the MIL does not illuminate. Of the following, which is the
least likely cause for this condition?
1) The bulb is burned out
2) The fuse supplying power to the MIL is open
3) There is a short to ground between the ground side of the MIL and the PCM
4) There is an open in the circuit between the ground side of the MIL and the PCM
3) The Catalyst Monitor - Correct Answer-Which of the following monitors does not run
continuously?
1) The Fuel System Monitor
2) The Comprehensive Component Monitor
3) The Catalyst Monitor
4) The Misfire Monitor
3) The ECT is shorted - Correct Answer-The parameter display for the ECT shows a
temperature of -22 degrees F after the engine has been running for several minutes. Of
the following, which is the LEAST likely cause for this reading?
1) The ECT is disconnected
2) The ECT is open
3) The ECT is shorted
4) The ECT ground is open
3) Plugged injectors - Correct Answer-A DTC P0171 (Bank 1 System too Lean) is
stored. Is is the only code stored. Of the Following, which is the MOST likely cause for
this code?
1) High fuel pressure
2) Leaking injectors
3) Plugged injectors
4) A short to ground in the MAP sensor signal wire to the PCM
1) PCV, TAC, EVP, EGR, SPK - Correct Answer-Refer to illustration #1 for the following
question.
A 1976 Jeep vehicle is in for Smog Check. It has a 4.2 liter engine and is federal
certified. The vehicle is equipped with a manual transmission. Which of the following
emission control systems would required for this vehicle?
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Download Smog Level 1 Exam: Automotive Diagnostics & Emissions Control and more Exams Motor Vehicle Design in PDF only on Docsity!

Smog Level 1 Exam With 100% Correct

Answers 2024/

  1. There is a short to ground between the ground side of the MIL and the PCM - Correct Answer-During bulb check, the MIL does not illuminate. Of the following, which is the least likely cause for this condition?
  2. The bulb is burned out
  3. The fuse supplying power to the MIL is open
  4. There is a short to ground between the ground side of the MIL and the PCM
  5. There is an open in the circuit between the ground side of the MIL and the PCM
  6. The Catalyst Monitor - Correct Answer-Which of the following monitors does not run continuously?
  7. The Fuel System Monitor
  8. The Comprehensive Component Monitor
  9. The Catalyst Monitor
  10. The Misfire Monitor
  11. The ECT is shorted - Correct Answer-The parameter display for the ECT shows a temperature of - 22 degrees F after the engine has been running for several minutes. Of the following, which is the LEAST likely cause for this reading?
  12. The ECT is disconnected
  13. The ECT is open
  14. The ECT is shorted
  15. The ECT ground is open
  16. Plugged injectors - Correct Answer-A DTC P0171 (Bank 1 System too Lean) is stored. Is is the only code stored. Of the Following, which is the MOST likely cause for this code?
  17. High fuel pressure
  18. Leaking injectors
  19. Plugged injectors
  20. A short to ground in the MAP sensor signal wire to the PCM
  21. PCV, TAC, EVP, EGR, SPK - Correct Answer-Refer to illustration #1 for the following question. A 1976 Jeep vehicle is in for Smog Check. It has a 4.2 liter engine and is federal certified. The vehicle is equipped with a manual transmission. Which of the following emission control systems would required for this vehicle?

1) PCV, TAC, EVP, EGR, SPK

2) PCV, TAC, EVP, AIS, EGR

3) TAC, PCV, AIS, EGR, CAT

4) PVC, TAC, EGR, AIS, OXY, CAT

14.7 pounds of air to one pound of fuel. - Correct Answer-What does it mean that the ideal air/fuel ratio is 14.7:1? +40% - Correct Answer-An OEM scan interface shows a STFT of 179. How will the scan tool display this STFT in Freeze Frame?

  1. There is an exhaust leak. - Correct Answer-The four-gas readings of a vehicle you are testing at curb idle; HC--------------21ppm CO--------------0.0% CO2------------- 6 .3% O2--------------12.3% Which of the following is the most likely condition, causing these readings?
  2. There is an exhaust leak.
  3. The ECT sensor is returning a voltage too high back to the PCM.
  4. The O2 sensor is not functioning.
  5. The PCM is bad and must be replaced.
  6. The Nix would increase at cruise. - Correct Answer-Please refer to illustration #12 for the next question. If the hose would be become broken at point "Y" of the illustration, what would be the result, if any, of the resulting emissions?
  7. The CO would increase.
  8. There would be no effect on emissions.
  9. The NOx would increase at idle.
  10. The Nix would increase at cruise.
  11. There is a vacuum leak. - Correct Answer-You are testing a multi-port vehicle. The idle is too high and the EIS will not test the vehicle at idle. You get authorization from the customer to adjust the idle speed. You scan the vehicle and notice the IAC count to be "0". What is the most likely cause of this high idle speed?
  1. The EGR is coming on too soon. - Correct Answer-The vehicle stumbles on slow acceleration. The TPS is within specs and adjusted properly. The fuel pressure and volume check out OK. The ignition system is functioning normally. What would be the most likely cause of the stumble?
  2. The timing is too far advanced.
  3. The vehicle has bad fuel in it.
  4. The timing belt has slipped.
  5. The EGR is coming on too soon.
  6. The engine would run poorly when cold. - Correct Answer-The heated grid type EFE has been disconnected. How would this effect the running of the engine?
  7. The engine would run poorly when cold.
  8. It would run rich after warm up.
  9. The engine would run lean after warm up.
  10. The engine would run rich at high RPM after warm up.
  11. NOx and HC in the presence of sunlight. - Correct Answer-Photochemical smog is a product of:
  12. HC and CO in the presence of sunlight.
  13. NOx and HC in the presence of sunlight.
  14. CO and NOx in the presence of sunlight.
  15. HC and NOx in the absence of sunlight
  16. A bad spark plug wire - Correct Answer-Please refer to illustration #8 for the next question. The four gas readings, found in illustration #8 were recorded when the engine was idling. What is the most probable cause of this emissions failure?
  17. A bad spark plug wire
  18. System is running too lean
  19. System is running too rich
  20. Normal gas readings
  21. Thermostat stuck open - Correct Answer-A vehicle has failed the emissions test because of high CO readings. The following scan data was obtained from the vehicle after the emissions test was completed. Using the scan data information, what could cause the vehicle to fail the CO cut point? RPM------------------- 1450 Collant Temp. --------190 deg. F

MAP ------------------3.8 volts O2 sensor voltage----.780 (fixed)

  1. Thermostat stuck open
  2. A leak in the MAP signal hose
  3. O2 sensor biased
  4. O2 sensor lazy
  5. Low fuel pressure - Correct Answer-HC--------------12ppm CO--------------0% NOx-------------1860ppm O2---------------3.4% A vehicle has failed an emissions test. The five gas readings , shown above, were taken with the engine under a light load, using a dynamometer. Of the following, which would be the most likely v=cause for this emission failure?
  6. High fuel pressure
  7. TPS failure
  8. Low fuel pressure
  9. Restricted exhaust.
  10. The MAP sensor sending a voltage signal too high for the actual engine load. - Correct Answer-NOx -------------8ppm CO---------------5% HC---------------240ppm CO----------------10.7% O2----------------.02% The five gas readings, shown above, were taken while the engine was at normal operating temperature and at idle. Of the following, which malfunction could cause this type of exhaust readings?
  11. Low compression on one cylinder.
  12. MAP sensor sending a voltage signal too low for the engine load.
  13. The ECT sensor sending a voltage too low for the engine temperature.
  14. The MAP sensor sending a voltage signal too high for the actual engine load.
  1. High fuel pressure
  2. Biased O2 sensor
  3. Vacuum leak at the base of the TBI unit
  4. ECT signal voltage too high for actual temperature.
  5. Intermittent failure on the MAP sensor - Correct Answer-Please refer to illustration # for the next question. This vehicle experiences an intermittent misfire while under acceleration. Looking at the live data recorded, what is the most probable cause of this failure?
  6. Faulty ECT not changing temperature
  7. Intermittent failure on the MAP sensor
  8. Intermittent Failure on the O2 sensor
  9. Stuck TPS sensor
  10. Run an ignition test on a lab scope - Correct Answer-The customer complains of a rough running condition. The vehicle fails the SMOG CHECK. With this information along with the four gas readings found on illustration #7, What is should be done next?
  11. Run an ignition test on a lab scope
  12. Do a Vacuum test
  13. Do a fuel pressure test
  14. Do a fuel volume test
  15. 2500°F - Correct Answer-At what combustion temperatures are high/unacceptable levels of NOx emissions created?
  16. 250°F
  17. 2500°F
  18. 2500°C
  19. 1500°F
  20. False - Correct Answer-All EGR valves can be tested by applying vacuum (via a hand vacuum pump) to the valve and watching for the engine to run rough or stall.
  21. True
  22. False
  23. No answer text provided.
  24. No answer text provided.
  25. NOx - Correct Answer-Which exhaust emission is formed by high combustion chamber temperatures?
  26. CO
  27. NOx

3) HC

4) CO

  1. ECT circuit fault - Correct Answer-Please refer to illustration #13 for the next question. A Port Fuel injection vehicle is running rough at times. Customer complaints about stalling issues at times and high fuel consumption. Refer to the data on illustration #13, What is the most probable cause of this failure?
  2. ECT circuit fault
  3. TCC solenoid not coming on
  4. BARO sensor high input
  5. Lazy O2 sensor
  6. Too rich - Correct Answer-After the following exhaust emissions were measured, how was the engine operating? HC=766 PPM CO2=8.2% CO=4.6% O2=0.1%
  7. Too lean
  8. Too rich
  9. Both technicians - Correct Answer-A P0401 DTC (exhaust gas recirculation flow insufficient) is being discussed. Technician A says that a defective EGR valve could be the cause. Technician B says that clogged EGR passages could be the cause. Which technician is correct?
  10. Technician A
  11. Technician B
  12. Both technicians
  13. Neither technician
  14. Technician A - Correct Answer-A vehicle fails an emission test due to excessive carbon monoxide indicating a rich air fuel mixture. Technician A says that a saturated charcoal canister could be the cause. Technician B says that a stuck-closed EVAP purge solenoid could be the cause. Which technician is correct?
  15. Technician A
  16. Technician B
  17. Both technicians
  18. Neither technician
  19. Rich mixture - Correct Answer-HC and CO are high and CO2 and O2 are low. This could be caused by a ________.
  20. Rich mixture
  1. Both technicians - Correct Answer-Technician A says that carbon inside the engine can cause excessive NOx to form. Technician B says that excessive NOx could be caused by a cooling system fault causing the engine to operate too hot. Which technician is correct?
  2. Technician A
  3. Technician B
  4. Both technicians
  5. Neither technician