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5-6

Fundamentals

Hydrocarbons (

)

is an organic compound composed of one hydrogen (

) and

one carbon (

) atom. The

in gasoline engine exhaust is

unburned gasoline vapor that is measured in parts per million
(ppm).

levels in engine exhaust vary with the air-fuel ratio.

The lowest

emissions occur at an air-fuel ratio of about 16:1.

Since no engine combustion is perfect, some vaporized

in the

combustion chamber remains unburned and leaves the engine
with exhaust gases. The amount of

depends largely on

combustion chamber design.

Also,

increases dramatically when the fuel mixture is too lean

or rich to support complete combustion, or when ignition does not
occur in the combustion chamber at all.

When compared along with

and

readings,

can also

indicate catalytic converter efficiency.

Gasoline evaporating from the carburetor and the fuel tank are
also sources of

, known as evaporative emissions.

Figure 5-4

: Hydrocarbons Versus Air-Fuel Ratio

Содержание DGA 1000

Страница 1: ...DGA 1000 Diagnostic Gas Analyzer...

Страница 2: ......

Страница 3: ...eatures 2 1 Measurement Screen 2 1 CO Corrected 2 2 Lambda and AFR Calculation 2 4 Lambda l and Catalytic Converter Efficiency 2 4 O2 and NOx Measurement 2 4 Air Fuel Ratio and the Stoichiometric Poin...

Страница 4: ...Catalytic Converters 5 12 Vehicle Testing Procedures 6 1 Testing Gasoline Fueled Vehicles 6 1 Testing Propane Fueled Vehicles 6 1 Data Collection Modes 6 2 Engine Conditioning 6 2 Tail Pipe Exhaust Ga...

Страница 5: ...This section contains a list of conventions used in text Check Note A check note provides additional information about the subject in the preceding paragraph Example Keep the probe tip openings clean...

Страница 6: ...ult in death or serious injury to the operator or to bystanders Indicates a potential hazard which if not avoided could result in death or serious injury to the operator or to bystanders Indicates a p...

Страница 7: ...ydrocarbons Hz hertz km h kilometers per hour lb pound LPG Liquefied Petroleum Gas Propane mV millivolt MIL malfunction indicator lamp NDIR Non Dispersive Infrared NO nitric oxide NO2 nitrogen dioxide...

Страница 8: ...a registered trademark of Snap on Tools Company Copyright Information DGA 1000 Gas Analyzer Operating Instructions 2001 Snap on Diagnostics The information specifications and illustrations in this ma...

Страница 9: ...cturer cannot possibly anticipate or provide advice or safety messages to cover every situation It is the automotive technician s responsibility to be knowledgeable of the system that is to be tested...

Страница 10: ...ormal type states the hazard Bold type states how to avoid the hazard Italic type states the possible consequences of not avoiding the hazard An icon when present gives a graphical description of the...

Страница 11: ...a test with the engine running Unless instructed otherwise set the parking brake and put the gear selector in neutral standard transmission or park automatic transmission If the vehicle has an automat...

Страница 12: ...connections and hot or moving parts can cause injury Misdiagnosis may lead to incorrect or improper repair and or adjustment Do not rely on erratic questionable or obviously erroneous test informatio...

Страница 13: ...the fuel ignition and emission control systems are functioning properly when exhaust gas concentrations are within limits specified by the vehicle manufacturer or the local state or federal governmen...

Страница 14: ...view follow Figure 1 1 A 9 Video Display Screen Displays all screen information and symbols available for use with each screen B Enter Key and Arrow Keys Use the Middle ENTER key to select a chosen it...

Страница 15: ...display E PRINT Key Use to Access message customer input screen Press TWICE to start printing F Freeze Store Key Use to Stop or freeze all test screen information necessary for saving a screen to memo...

Страница 16: ...In line water drain filter D O2 and NO Sensor Cover Remove this cover to replace O2 or NO cells O2 sensor detects concentrations of oxygen in the exhaust gas sample NO sensor optional detects concentr...

Страница 17: ...Connect the exhaust sample hose probe to this inlet O Water Outlet Sample filter bowl water drain P Calibration Gas Inlet Use this inlet to supply calibration gas to the analyzer Q Optional Lightpen E...

Страница 18: ...symbols to allow easy navigation around the various menu and screen displays using the ENTER and ARROW key pad Additional details of these symbols follow Figure 1 3 Use the arrow keys followed by the...

Страница 19: ...of 30 minutes while the Auto zero Auto calibration symbol displays After this time the analyzer stops measurements and performs an Auto zero Bench Exhaust Flow Problem Indicates that the gas bench ex...

Страница 20: ...Chapter 4 Maintenance for a list of error codes Standby Select with arrow keys and press ENTER to put the analyzer in the STANDBY mode The pump stops running Press ENTER to start the pump again The an...

Страница 21: ...imit set 2 is active when data buffer 2 is selected Measurements are continuously compared with the limit values and indications are given on the Measurement Screen as too high too low or correct Resu...

Страница 22: ...mory Buffer 2 Select to clear data memory buffer 2 Left Arrow Key Select left arrow key to return to Measurement Screen Right Arrow Key Select right arrow key and ENTER to add a text message to printo...

Страница 23: ...bols There are also symbols used to indicate the presence of additional screens and selections The following symbols indicate You can move to the previous line There is a previous screen You can move...

Страница 24: ...r and or letter keys to enter field information Optional Lightpen Use the optional lightpen part number 7009E9321 97 to select menu symbols on the screen and to switch between screens by positioning t...

Страница 25: ...ey for the Vehicle set up menu C Eng Data Not used for DGA 1000 Gas Analyzer emissions testing D Tools Not used for DGA 1000 Gas Analyzer emissions testing E Help Not used for DGA 1000 Gas Analyzer em...

Страница 26: ...d bottom of screen N NO Not used for DGA 1000 Gas Analyzer emissions testing O Enter Press the ENTER key to complete data entry P Left Arrow Press to move cursor toward left side of screen Q Function...

Страница 27: ...O2 0 00 18 00 5 HC 0 2000 3 2000 5000 5 5000 9999 5 O2 0 00 25 00 5 NO 0 5000 5 RPM 0 9999 0 5 C 10 150 5 F 14 302 5 Lambda 0 500 2 000 calculated AFR 5 00 25 00 calculated Operating Conditions Maximu...

Страница 28: ...lls like gasoline brake fluid cleaning solvents etc from the exterior of the analyzer immediately to protect the finish XAlways keep the calibration gas bottle valve in the closed position except when...

Страница 29: ...wer cord into the AC power source F on the back panel of the analyzer Plug the other end into a standard 120VAC grounded electrical outlet See Figure 1 10 Make sure the voltage switch G at the main in...

Страница 30: ...ust gas probe into the vehicle tail pipe Make sure the sample probe is fully inserted 2 Connect the RPM pickup as follows Use the grey inductive pickup part number 6004E9312 95 when a spark plug wire...

Страница 31: ...r stop comes in contact with the dipstick tube Since the DGA 1000 Gas Analyzer was released two types of oil temperature probes have been used Euro and US probe Euro probe part number 6004E9312 99 is...

Страница 32: ...kes about 2 5 minutes When the unit starts up after a Standby period it performs the Auto zero calibration and HC hang up check When the analyzer completes the warm up cycle it enters in the operating...

Страница 33: ...general purpose display can be used for diagnostic and repair A Warm up Auto zero calibration and HC hang up Check is performed automatically when the analyzer is turned ON The Measurement Screen dis...

Страница 34: ...easurement correction when CO and CO2 are less than 15 for gasoline See Figure 2 2 This correction may be required for vehicles with an air leak in the vehicle exhaust system While the correction may...

Страница 35: ...Analyzer Screen Display Features 2 3 The following is a chart showing the resulting content of a CO correction Figure 2 2 Corrected CO...

Страница 36: ...s achieved when Lamda 1 00 Smaller numbers indicate a rich air fuel ratio larger numbers indicate a lean air fuel ratio The figure below shows the relationship between certain pollutant exhaust gases...

Страница 37: ...combustion process burns fuel and oxygen The following by products result from the combustion process Mechanical force and heat The pollutants HC hydrocarbons CO carbon monoxide NOx oxides of nitrogen...

Страница 38: ...st are found in Chapter 3 Vehicle Testing 2 Catalytic Efficiency Test A preprogrammed special test procedure to determine how well a catalytic converter is functioning Detail procedures are found in C...

Страница 39: ...e must be inserted in the exhaust of the vehicle The pump draws exhaust gases into the system the exhaust sample probe must be blocked and then system checks if the CO2 value changes When the CO2 chan...

Страница 40: ...nt Screen To change the setting Press ENTER Arrow to select choice and then Press ENTER for desired choice For additional information refer to Lambda and AFR Calculation page 2 4 LPG Select the correc...

Страница 41: ...r is displayed in the 24 hour format in the set time screen i e 1 00 pm 13 Standby Mode The system automatically goes into a standby mode by selecting the elapsed time 5 min 15 min 30 min or 60 min af...

Страница 42: ...for the customer information you want to use The information entered on this screen as shown in Figure 2 10 prints on the Test Results Printout The procedure for entering data is similar to the Print...

Страница 43: ...can NOT be changed by the operator Two menu choices are available as indicated by the icon The left arrow returns you to the Main Test Menu Gas tags values can be set by the operator in Maintenance m...

Страница 44: ...in Figure 2 13 2 Settings View Only Three Settings Screens display DGA 1000 Gas Analyzer settings The settings are configured during first installation of the analyzer and can only be changed by a Ser...

Страница 45: ...een gives an overview of last checks and calibrations It also shows when the NO cell and O2 cell need to be replaced The analyzer automatically indicates when these cells need replacement Figure 2 15...

Страница 46: ...he operator using this page The values in Figure 2 18 are recommended Type 4 NO is used only when the analyzer has the NOx option installed 5 Factors View Only Factors Screen shows the calibration fac...

Страница 47: ...ble to a Service Representative 8 System Status Printout When the System Status Printout Screen displays press the right arrow key to print Service The Service Menu can only be accessed by an authoriz...

Страница 48: ...2 16 Analyzer Screen Display Features...

Страница 49: ...ection repairing and replacing items as required Careful visual checks may lead to correcting a problem Examine all the following systems and components Fluid Levels Engine oil Transmission fluid Cool...

Страница 50: ...stem circuits Charging system circuits Ignition system circuits Check ignition wires for cracking hardness proper routing and carbon tracking Fuel system Battery Check state of charge general conditio...

Страница 51: ...ichment A cold engine test contaminates the sampling filter quickly requiring more frequent analyzer service intervals XBefore testing tail pipe emission levels make sure the engine is at normal opera...

Страница 52: ...t setting to display engine RPM Press ENTER and the arrows until the correct number displays as follows and then press ENTER to select Setting 1 use when RPM pickup is connected to a single plug wire...

Страница 53: ...ases Set to OFF when no limits are used Screen Indicators If limits are on arrows appear on the Gas display screen to indicate if the values are as shown below Up arrow measured value is above the lim...

Страница 54: ...um OIL decimal point for example a maximum CO would be 2 00 a negative value This should never be used All minimum and maximum will accept 6 characters For example for a 1996 vehicle the following lim...

Страница 55: ...Vehicle Testing 3 7 When settings are changed and a measurement was previously stored the ongoing data in the memory is cleared Set 1 Limit Screen 1 Set 1 Limit Screen 2 Changing Settings...

Страница 56: ...test are completed insert the sample probe in the tail pipe and connect an exhaust removal system 4 Once gases display up to two sets of data may be stored using the key on the analyzer front panel Pr...

Страница 57: ...ed limits repairs or adjustments are indicated The test procedure used in the program is referred to as a pre condition two speed idle and it consists of a number of steps that must be followed exactl...

Страница 58: ...t shows the engine speed in RPM 14 Hold engine at that speed for the duration of the test The countdown timer on the TSI Test Screen shows the seconds remaining for the test 15 When the test is comple...

Страница 59: ...RTANT SAFETY INSTRUCTIONS The catalytic converter test kit part number EAK0232L00A is intended for use by properly trained skilled professional automotive technicians Safety warnings and cautions in t...

Страница 60: ...se to set rate of propane flow B Velcro Strap Part number 5 3245 Attaches flow meter to propane tank C Propane Enrichment Assembly Part number EAA0259L00A Controls flow of propane D Propane Tank Tank...

Страница 61: ...f the catalytic converter The catalytic converter requires precise control of the air fuel ratio to operate at peak efficiency Anything that disrupts the air fuel ratio such as an engine that burns oi...

Страница 62: ...f the substrate is broken the catalytic converter will soon fail and may plug the exhaust XAlways follow vehicle manufacturer specifications when working on emission control devices to comply with ant...

Страница 63: ...amount of propane through a large manifold vacuum source on the engine like the PCV or power brake vacuum booster hose XDo not exceed specified propane flow Excessive propane overheats the catalytic...

Страница 64: ...ery feed to ignition coil s Removing secondary coil wire from distributor cap and ground it XDisabling fuel system may require Removal of fuse s Disconnect injector harness Disconnect fuel pump connec...

Страница 65: ...the fuse panel removing this fuse can disable the fuel injectors Sometimes it disables the fuel and ignition systems Be sure to check for spark IMPORTANT Read trouble codes before removing fuses Lear...

Страница 66: ...me familiar with it before attempting to diagnose a customer vehicle 4 Start the engine and run at high idle until the oil temperature is 176 F or select the right arrow key and ENTER to continue Engi...

Страница 67: ...ytic Converter cooled down the following message appears Catalytic Converter cooled down Select next page to repeat warm up 14 Crank the engine Start cranking and Propane flow in 5s Throttle valve com...

Страница 68: ...3 20 Vehicle Testing...

Страница 69: ...ubleshooting information Accessory Kit information Maintenance Parts information and a list of Options are found at the end of the manual Maintenance Schedule The following items require periodic main...

Страница 70: ...re minimum intervals for replacement A Filter Secondary Inline Sample secondary in line filter Replace every six months with part number 7096E9061 03 To replace the filter remove the tubing from each...

Страница 71: ...of the screen or if a low flow symbol appear at any time during operation the primary filter must be replaced immediately Stop testing and perform sample system maintenance The low flow can also be c...

Страница 72: ...esults If a failure occurs disconnect the hose at the analyzer and repeat the procedure If a pass occurs fix hose and probe If a fail occurs check primary filter and then contact your Service Represen...

Страница 73: ...commended Type 3 Low used to enter low range NO if required NO 300 Type 4 High used to enter high range NO if required NO 3000 Only Equiserv can perform a two point calibration 6 Gas Calibration As de...

Страница 74: ...again contact your Service Representative Test Leads Inspect all test leads weekly for cuts kinks and abrasions etc Take care when routing leads across an engine that they do not come into contact wit...

Страница 75: ...zine gasoline etc They can damage plastic components and affect correct operation of the components Clean any surface spills immediately to protect the keyboard and remote control CRT Screen Clean the...

Страница 76: ...away any debris using compressed air Do not apply compressed air to the probe tip without disconnecting the sample hose from the filter assembly Back pressure could damage the sampling system Replace...

Страница 77: ...e measurements are stopped The measurements can be continued for a maximum of half an hour while the symbol is on Then the analyzer stops the measurements and the Auto zero is performed Output Flow Fa...

Страница 78: ...ppears only when an NO cell is installed optional The lifetime of the NO cell has expired The NO cell needs replacement Contact your Service Representative CHANGE O2 SENSOR Solution Change the O2 cell...

Страница 79: ...FLOW FAILURE Solution The Gas Sample Outlet is clogged Activate the STANDBY mode Clean the Gas Sample Outlet Deactivate the STANDBY mode PRE WARNING CHANGE O2 SENSOR Solution Contact your Service Rep...

Страница 80: ...E9323 46 Inline secondary filter 7096E9061 03 Grey RPM pickup 6004E9312 95 Keyboard kit 7009E9321 99 Stand EEKR104A Manual ZDGA1000 Maintenance Parts Inline secondary filter 7096E9061 03 Inline water...

Страница 81: ...f hydrocarbon fuel and air in the combustion chamber This action causes the compressed fuel mixture to expand producing the pressure required to move the pistons downward Figure 5 1 shows the air fuel...

Страница 82: ...oo much air or too little fuel A rich fuel mixture has too much fuel or too little air Combustion Emissions Internal combustion engines are not 100 efficient even with ideal fuel mixtures For this rea...

Страница 83: ...gine especially NO and NO2 The X subscript in place of numbers indicates that all NO compounds are included Of the nitrogen oxide compounds NO is the only compound with appreciable importance to engin...

Страница 84: ...s maximum cycle temperature which increases emissions An increase in intake manifold vacuum decreases load and temperature and increases the mass of residual gases As a result combustion time increase...

Страница 85: ...alytic Converter A dual bed or three way type catalytic converter in good working order can reduce NOx emitted from the engine as it passes through the catalytic converter If the mixture and exhaust a...

Страница 86: ...rized HC in the combustion chamber remains unburned and leaves the engine with exhaust gases The amount of HC depends largely on combustion chamber design Also HC increases dramatically when the fuel...

Страница 87: ...tion of CO in the exhaust is higher Therefore anything causing a rich air fuel ratio results in high CO concentrations in the exhaust Figure 5 5 shows that the CO level decreases as the air fuel ratio...

Страница 88: ...less CO2 is a good indicator of combustion efficiency because its volume in the exhaust peaks just before the stoichiometric air fuel ratio CO2 peaks when the combustion chamber fuel mixture approache...

Страница 89: ...t gas after combustion indicates air fuel ratio leanness In Figure 5 7 the O2 concentration is at a steady low level when the fuel mixture is richer than about 15 1 because all available O2 is consume...

Страница 90: ...over This is due to more complete combustion occurring at stoichiometric ratios Richer than ideal mixtures cause CO levels to increase leaner mixtures have little effect CO2 levels are highest when a...

Страница 91: ...mbda is less than one when the air fuel ratio is rich and is greater than one when lean Because combustion temperatures and the air fuel ratio requirements can change in engines under dynamic load the...

Страница 92: ...ers contain a combination of three noble metals platinum Pt palladium Pd and rhodium Rh These metals are applied to small beads or ceramic baffle materials called substrates that provide a tremendous...

Страница 93: ...d With a reduction reaction these catalyst reduced NOx to N2 and O2 Three way converters oxidize HC and CO and reduce NOx These converters are even more sensitive to air fuel ratio because the reducti...

Страница 94: ...fall to slightly lower values as the air fuel mixture continues to get leaner Catalytic converters oxidize HC CO and NOx producing H2O CO2 and N2 Therefore monitoring HC and CO does not give an accur...

Страница 95: ...auses for abnormal exhaust concentrations provides so many variations that a different approach must be used to interpret the readings For additional information refer to Chapter 7 Diagnostic Techniqu...

Страница 96: ...ollow for a valid emission test 1 Warm the engine to normal operating temperature then insert the exhaust sample probe into the tail pipe 2 Raise the engine speed to 2000 RPM and maintain for 30 secon...

Страница 97: ...in the theory and interpretation sections of this manual to aid the diagnosis Consider also the vehicle owners complaint and or the symptoms that relate to the complaint Drive ability and emissions s...

Страница 98: ...ycle Hard Acceleration Drive Cycle High Cruise Drive Cycle or On Board Diagnostic OBD II Drive Cycle The 90 Second Hard Acceleration and High Cruise Drive Cycles are typically used for drive ability t...

Страница 99: ...seconds Accelerate to about 50 mph 80 km h at medium throttle If the vehicle has manual transmission it should be in high gear at 80 km h Vary the speed between about 50 to 55 mph 80 to 90 km h for a...

Страница 100: ...n when using the dynamometer While driving OBD II systems perform a series of tests on specific systems monitoring then adjusting to compensate for those conditions These conditions are called an OBD...

Страница 101: ...xidizing Catalyst E O2 Sensor F Check Valves G Air Pump H Port Solenoid I Converter Solenoid J Electrical Signals from ECM K Bypass Air to Atmosphere These systems usually consist of a belt driven air...

Страница 102: ...repairs Carburetor Adjustments Vehicles Without Feedback Fuel Systems Adjusting the carburetor using the analyzer requires an understanding of how each adjustment can affect the air fuel mixture Adju...

Страница 103: ...op Adjustment Test 1 Turn the mixture screw s to obtain the highest RPM If there are two adjustment screws adjust each screw for a 10 RPM drop 20 RPM total and back each one out 1 4 turn 2 Lean the mi...

Страница 104: ...for all three throttle changes will usually be between 1 5 vol and 3 5 vol If the CO reading decreases before increasing or does not increase the accelerator pump is not functioning properly Check th...

Страница 105: ...f the CO does not increase a malfunctioning power valve is indicated A momentary increase in and return to the original CO and HC readings is expected when the throttle is opened and returned to fast...

Страница 106: ...sting Tip XCombustion gases leaking into the cooling system are usually more easy to detect when the engine is operated under load while sampling above the cap opening Test 1 Remove the radiator cap 2...

Страница 107: ...ing suspected leak areas XAir stream in the immediate area may affect test results Shield the probe from wind draft or stop the engine when testing near a running engine Small leaks may require testin...

Страница 108: ...r systems carefully check the fresh air side of the check valve while the engine is running An HC reading in this area suggests a defective check valve which can cause vehicle performance problems sin...

Страница 109: ...n air cooled engines test around heater ducts for exhaust fumes Test 1 Place the probe inside the vehicle through an open window Close the window on the hose being careful not to pinch it 2 Allow the...

Страница 110: ...therwise working properly In these cases valve timing problems may be noticed when the engine turns over A change in normal engine cranking rhythm could indicate valve timing problems Test 1 Insert th...

Страница 111: ...e engine speed load or both Defeat air management Enrich the fuel mixture with propane Create a vacuum leak to lean the fuel mixture and Use other test equipment such as an oscilloscope vacuum gauge o...

Страница 112: ...system vacuum leaks and fuel mixture problems Miscellaneous When CO goes up O2 goes down When O2 goes up CO goes down O2 combines with HC to form CO2 and H2O O2 combines with CO to form CO2 O2 and CO...

Страница 113: ...r Misfiring at cruising speeds Burned valves Burned pistons Scored cylinders Spark knock or ping Slightly Lean High gas mileage Low exhaust emissions Reduced engine power Slight tendency to knock or p...

Страница 114: ...l injectors incorrect carburetor adjustment power valve leaking choke operating rich float level too high air filter dirty EVAP canister purge system fault PCV system problem engine control computer m...

Страница 115: ......

Страница 116: ...ZDGA1000 Rev B 2001 Snap on Tools Company Printed in U S A 7 01 420 Barclay Blvd Lincolnshire Il 60069 3606 Tel 847 478 0700 Fax 847 478 7311...

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