FONT-FAMILY: Tahoma; FONT-SIZE: 9pt; mso-fareast-font-family: Times New Roman; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN ; mso-bidi-language: AR-SA">1.04, Can be regarded as an ideal match. at this time, CO,HCReduce, but may cause exhaust gasNOXThe increase in concentration.Greater than this value, indicating that the air-fuel ratio is too large,If the mixture is too lean and less than this value, the air-fuel ratio is too small and the mixture is too rich.
4.Exhaust gas detection method and matters needing attention
General five gas exhaustAnalyzerAll have three test methods: idle speed test, dual idle speed test and ordinary test.The first two arecarDuring the annual inspection, we use ordinary tests to test the changes in engine exhaust components in real time during maintenance.Most cars nowadays are equipped with catalytic converters. When analyzing engine failures, the exhaust gas sampling should be before the catalytic converter (before the catalytic converter).exhaust pipeThere is usually a special sampling hole plugged with bolts. The bolts can be removed and the probe of the exhaust gas analyzer can be inserted from here). When testing the exhaust gas of an engine equipped with secondary air injection, the system should be temporarily stopped.Before testing the exhaust gas, the engine should reach the normal operating temperature, and the insertion depth of the sampling probe should not be less than40cm.
5. Exhaust gas analysis example
5.1 Honda AccordCD4, The engine model isF22B1, Waste oil
Four-gas exhaust gas analyzer test results:
CO 4.6%,HC 356 ppm,CO2 13.6% , O2 0.56% ,800change/Minute
Analysis of test results:
HCandCOHigh whileCO2 ,O2Low indicates that the mixture is rich.The focus should be on checking the air and fuel supply system
Troubleshooting:
There are many factors that cause the mixed gas to be thick and should be investigated.Use Yuan ZhengX-431Read no trouble code, checkair filterClean, check that the fuel pressure is250Kpanormal.Start the engine, run at idle speed, and read the fuel injection pulse width as3.6ms,The normal injection pulse width of this type of engine is2.4ms, It is obvious that the value exceeds the standard. Read the water temperature,Throttle, Ignition advance angle, intake pressure,Rotating speedWait for the signals to be in the normal range, check carefully and find that the intake air temperature signal is fixed at20℃ does not change, and the signal should be at40-60℃ between.FromIntake manifoldRemove thesensor, Use a hair dryer to measure its resistance while heating, always in2300Ω does not change, which proves that it has been damaged.After replacing the new part, the fuel injection pulse width is2.4ms,Troubleshooting. Because the intake air temperature signal is a fuel injection correction signal, if it is damaged, the engine computer will be incorrectly corrected, resulting in a rich mixture.
Exhaust retest results:
CO 0.34%,HC 45 ppm,CO2 14.8% , O2 1.46% ,800change/Minute
All data are within the standard, troubleshooting.
5.2 AudiA6carV6 2.8LThe electronically controlled engine has a slight jitter when idling, and the acceleration is slow
Exhaust gas measurement results:
COmake an appointment0.3%~0.5%,HCfor200-500 ppm, And fluctuate within this range.
Analysis of test results:
COValue is low, whileHCThe value is unstable, indicating that there is an intermittent misfire fault.
Troubleshooting:
After inspection, it was found that there is a tankHigh-voltage lineThere is a slight short circuit(Leakage)Phenomenon, replace the high-voltage line for this reason.becauseSpark plugThe gap is too large and has been used2ten thousandkm, And also replaced at the same time. Clean the injectors and observe the atomization state and flow uniformity of the injectors in each cylinder.Re-inspection found that: engine jitter was slightly improved, but it was not completely eliminated; exhaust gas inspectionHCThe value has not dropped much and still fluctuates. Analysis believes that: the failure may still be caused by the fire.In order to further diagnose the fault,Exhaust manifoldOxygen SensorExhaust gas detection port next to(The port is usually sealed with a bolt)Perform exhaust gas detection.It turns out that the exhaust gas from the left cylinderCOValue in0.5%about,HCValue in125 ppmabout(Because it is measured in front of the catalytic converter, its value will be slightly higher than the measured value in the tail pipe), And the fluctuation is extremely small.And the right cylinder exhausts exhaust gasCOValue is also0.5%Around butHCValue125-250 ppmAnd there are fluctuations from time to time. So the problem should be in the right cylinder.For this reason, I checked the high-voltage line and spark plug of the right cylinder and found2Cylinder spark plug3One of the electrodes has a gap that is too small. After adjustment and re-installation, the fault is completely eliminated, and the exhaust gas detection value also meets the factory standard.
6. in conclusion
As a kind of auxiliary diagnostic equipment, exhaust gas analyzer is indeed a convenient and fast detection tool. The exhaust gas change rules and possible failures are summarized in Table 1:
Table 1 Exhaust gas test value and system failure
legend:L= Low H= High M= ModerateB= Change
CO CO2 HC O2 NOX Possible malfunction
HLHHM Misfire when the mixture is thick
LLHLM Intermittent misfire; low cylinder pressure
LLHHM Misfire when the mixture is lean
LMHMH Ignite prematurely
HMMLM Ignition too late
HLHLM Concentrated gas mixture
HL ML LM Mix is too thick
BLBMM EGRValve leak
LLLHL Leakage of emissions after the catalytic converter; leaking exhaust pipe
LHLLL High combustion efficiency, good catalytic converter function
Refer to Table 1, and then cooperate with other corresponding tests such as DTC analysis, data flow analysis, ignition waveform analysis, vacuum and pressure analysis, I believe it can quickly diagnose electronic control gasoline injection engine faults.
4.Exhaust gas detection method and matters needing attention
General five gas exhaustAnalyzerAll have three test methods: idle speed test, dual idle speed test and ordinary test.The first two arecarDuring the annual inspection, we use ordinary tests to test the changes in engine exhaust components in real time during maintenance.Most cars nowadays are equipped with catalytic converters. When analyzing engine failures, the exhaust gas sampling should be before the catalytic converter (before the catalytic converter).exhaust pipeThere is usually a special sampling hole plugged with bolts. The bolts can be removed and the probe of the exhaust gas analyzer can be inserted from here). When testing the exhaust gas of an engine equipped with secondary air injection, the system should be temporarily stopped.Before testing the exhaust gas, the engine should reach the normal operating temperature, and the insertion depth of the sampling probe should not be less than40cm.
5. Exhaust gas analysis example
5.1 Honda AccordCD4, The engine model isF22B1, Waste oil
Four-gas exhaust gas analyzer test results:
CO 4.6%,HC 356 ppm,CO2 13.6% , O2 0.56% ,800change/Minute
Analysis of test results:
HCandCOHigh whileCO2 ,O2Low indicates that the mixture is rich.The focus should be on checking the air and fuel supply system
Troubleshooting:
There are many factors that cause the mixed gas to be thick and should be investigated.Use Yuan ZhengX-431Read no trouble code, checkair filterClean, check that the fuel pressure is250Kpanormal.Start the engine, run at idle speed, and read the fuel injection pulse width as3.6ms,The normal injection pulse width of this type of engine is2.4ms, It is obvious that the value exceeds the standard. Read the water temperature,Throttle, Ignition advance angle, intake pressure,Rotating speedWait for the signals to be in the normal range, check carefully and find that the intake air temperature signal is fixed at20℃ does not change, and the signal should be at40-60℃ between.FromIntake manifoldRemove thesensor, Use a hair dryer to measure its resistance while heating, always in2300Ω does not change, which proves that it has been damaged.After replacing the new part, the fuel injection pulse width is2.4ms,Troubleshooting. Because the intake air temperature signal is a fuel injection correction signal, if it is damaged, the engine computer will be incorrectly corrected, resulting in a rich mixture.
Exhaust retest results:
CO 0.34%,HC 45 ppm,CO2 14.8% , O2 1.46% ,800change/Minute
All data are within the standard, troubleshooting.
5.2 AudiA6carV6 2.8LThe electronically controlled engine has a slight jitter when idling, and the acceleration is slow
Exhaust gas measurement results:
COmake an appointment0.3%~0.5%,HCfor200-500 ppm, And fluctuate within this range.
Analysis of test results:
COValue is low, whileHCThe value is unstable, indicating that there is an intermittent misfire fault.
Troubleshooting:
After inspection, it was found that there is a tankHigh-voltage lineThere is a slight short circuit(Leakage)Phenomenon, replace the high-voltage line for this reason.becauseSpark plugThe gap is too large and has been used2ten thousandkm, And also replaced at the same time. Clean the injectors and observe the atomization state and flow uniformity of the injectors in each cylinder.Re-inspection found that: engine jitter was slightly improved, but it was not completely eliminated; exhaust gas inspectionHCThe value has not dropped much and still fluctuates. Analysis believes that: the failure may still be caused by the fire.In order to further diagnose the fault,Exhaust manifoldOxygen SensorExhaust gas detection port next to(The port is usually sealed with a bolt)Perform exhaust gas detection.It turns out that the exhaust gas from the left cylinderCOValue in0.5%about,HCValue in125 ppmabout(Because it is measured in front of the catalytic converter, its value will be slightly higher than the measured value in the tail pipe), And the fluctuation is extremely small.And the right cylinder exhausts exhaust gasCOValue is also0.5%Around butHCValue125-250 ppmAnd there are fluctuations from time to time. So the problem should be in the right cylinder.For this reason, I checked the high-voltage line and spark plug of the right cylinder and found2Cylinder spark plug3One of the electrodes has a gap that is too small. After adjustment and re-installation, the fault is completely eliminated, and the exhaust gas detection value also meets the factory standard.
6. in conclusion
As a kind of auxiliary diagnostic equipment, exhaust gas analyzer is indeed a convenient and fast detection tool. The exhaust gas change rules and possible failures are summarized in Table 1:
Table 1 Exhaust gas test value and system failure
legend:L= Low H= High M= ModerateB= Change
CO CO2 HC O2 NOX Possible malfunction
HLHHM Misfire when the mixture is thick
LLHLM Intermittent misfire; low cylinder pressure
LLHHM Misfire when the mixture is lean
LMHMH Ignite prematurely
HMMLM Ignition too late
HLHLM Concentrated gas mixture
HL ML LM Mix is too thick
BLBMM EGRValve leak
LLLHL Leakage of emissions after the catalytic converter; leaking exhaust pipe
LHLLL High combustion efficiency, good catalytic converter function
Refer to Table 1, and then cooperate with other corresponding tests such as DTC analysis, data flow analysis, ignition waveform analysis, vacuum and pressure analysis, I believe it can quickly diagnose electronic control gasoline injection engine faults.
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