79-11 Evaluation of Applicability of Inspection/Maintenance Tests on a Dodge Aspen Prototype August 1979 by Thomas J. Penninga Technology Assessment and Evaluation Branch Emission Control Technology Division Office of Air, Noise and Radiation U.S. Environmental Protection Agency ------- Abstract This report presents testing results which were gathered to determine the suitability of existing I/M testing scenarios on a Chrysler car with a computer based emission control system. This car had a microprocessor based three-way catalyst control as well as computerized spark control. After suitable baselines were established, various components were made inoperative in the emission control system. Complete FTP, HFET, New York City Cycles, and I/M tests were run for each vehicle condition. This report presents the measured data taken during the tests. Background It is anticipated that, in the near future, electronics and computers will control many of the vital functions of automotive operation now regulated by mechanical means. As the Inspection/Maintenance effort is expanded it is a prerequisite that the test procedure used by the Inspection/Maintenance program be capable of determining equipment failure and parameter misadjustraent. With the advent of advanced elec- tronics into automobiles, it is necessary to evaluate the suitability of existing and proposed I/M tests to these future automobiles. To accom- plish this evaluation, several prototype cars containing the best pro- jected electronics of the future will be tested according to both the Federal Test Procedures and I/M tests. The derived data should indicate which I/M test best suite these automobiles. This report presents the data collected on the second such automobile tested by the EPA, a 1979 Dodge Aspen with an EFC and ESC microprocessor controlled emission control system. History . The Aspen was a late 1979 certification vehicle which was delivered to MVEL for I/M testing on March 20, 1979. Three baseline sets of data were run. The vehicle was shipped to Gulf Research Laboratory on March 29, J.979 where it underwent ambient emission testing. On June 8, 1979 the vehicle was delivered to MVEL. The I/M testing began on June 29, 1979. After two baseline sequences were run, the vehicle was tested with five different system deacti- vations. A final confirmatory baseline sequence was then run. Testing Procedure In order to test the vehicle, the following test scenario was used: a. Federal Test Procedure (FTP) 1979 procedure, non-evaporative, no heat build. ------- b. Raw HC/CO measurement, hood closed, fan off, idle-neutral. c. Highway Fuel Economy Test (HFET) immediately after FTP. d. Raw HC/CO measurement, hood closed, fan off, idle-neutral. e. New York City Cycle (NYCC) immediately after HFET. f. Raw HC/CO measurement, hood closed, fan off, idle-neutral. g. Federal Three Mode. The dynamometer was set at 1750 Ibs. inertia and horsepower was set at 6.4 hp at 25 mph and 13.7 hp at 52.0 mph. The hood was open and the auxiliary cooling fan turned on. Idle HC and CO measurements were taken in drive and in neutral on a garage type analyzer. h. Loaded Two Mode. The dynamometer was set at 17.3 IHP at 30 mph with the I.W. = 1750 Ibs. The hood was open and the auxiliary cooling fan turned on. Idle HC and CO measurements were then taken in neutral. i. Two Speed Idle Test with raw HC/CO garage type analyzer tested at 2500 rpm (neutral) and idle (neutral). The hood was closed and the auxiliary cooling fan turned off. j. Abbreviated I/M Cycle with raw HC/CO garage analyzer tested at idle (neutral momentarily accelerated to 2500 rpm (neutral), and then tested again at idle (neutral). The hood was closed and the auxiliary cooling fan turned off. k. Federal Three Mode (same as above). 1. Loaded Two Mode (same as above). m. Two Speed Idle Test (same as above). n. ' Abbreviated I/M Cycle (same as above). o. Prolonged Idle Cycle. With the cooling fan off and hood closed, idle (neutral) HC and CO measurements were taken every minute for 10 minutes on a garage type analyzer. A work sheet recording the I/M test results is shown in Attachment 1. ------- Vehicle Description The Dodge Aspen supplied by Chrysler for this testing was not a pro- duction vehicle but a 4000 mile emission-data-vehicle. Attachment 2 lists specific vehicle parameters. The most important aspect of this automobile's emission control system were the sensors, actuators, and microprocessor units. A complete description of these components is given in Attachment 3. Baseline Data To accurately determine the effect of the various vehicle conditions it was necessary to have an accurate baseline determined for each con- stitutent in each mode in every test type. Confirmatory baseline tests were run at the end of the test program. This baseline data is dis- played with the configuration data. Test Configurations After the baseline testing and sorting out of the testing procedures several components of the emission control system were, one by one, deactivated prior to vehicle testing. a. EGR Sensor Disconnected - Test Numbers 79-8152 and 79-8153 was done with the exhaust gas oxygen (EGO) sensor disconnected. This unit supplies a voltage signal to the FBC computer based on the oxygen content of the exhaust stream. By disconnecting the sensor the output voltage goes to zero and the closed loop system is deactivated. These tests are designated EGO Sensor disconnected. b. Coolant Temperature Switch Disconnected - Test Numbers 79-8154 and 79-8155 were run with the Coolant Temperature Switch disconnected. Because the EGO sensor does not perform pro- perly until it reaches temperature, the coolant sensor informs the FCC to operate in open-loop mode until EGO sensor tempera- , ture is reached. 3. Solenoid Actuated Vacuum Regulatory Disconnected - Test Num- bers 79-8156 and 79-8157 were run with the solenoid actuated Vacuum Regulator disconnected. This device connects the electrical signal from the FCC to a vacuum signal to control the carburetor in maintaining the A/F ratio at stoichiometric. Disconnecting the solenoid forces the system to run in a full rich condition. ------- d. Air Pump 100% Bypassed - Test Numbers 79-8158 and 79-8159 were run with the air pump diverted to atmosphere and both upstream and downstream air injection lines plugged. This air injec- tion oxidizes HC and CO at the exhaust port during warm-up and at the oxidation catalyst during regular operation. e. EGR Valve Disconnected - Test Numbers 79-8160 and 79-8161 were run with Exhaust Gas Recirculation (EGR) valve line discon- nected and plugged. This device recirculates exhaust gas into the inlet manifold which reduces combustion temperature there- by reducing NOx formation. f. Solenoid Actuated Vacuum Regulator - Full Lean - Additional tests were attempted with the solinoid wired to 12 volt DC. This condition would result in driving the FCC to a full lean condition. Because the vehicle stalled over 15 times in the preconditioning LA-4, this testing mode was terminated. Test Results The test results are given in several attachments. a. The FTP, HWFET, and NYCC with the corresponding raw HC/CO readings are given for baseline configuration studies in Attachment 4. The HC, CO, CO and NOx readings are in gms/mile while the fuel economy is in miles per gallon. The raw HC readings are in ppm Hexane and the raw CO readings are in percent. b. Attachment 5 presents the standard I/M test data. test was run twice, two sets of values are given. As each c. Attachment 5 also presents the Prolonged Idle Cycle Data. List of Attachments Attachment 1 Attachment 2 Attachment 3 'Attachment 4 Attachment 5 Attachment 6 I/M Test Result Work Sheet Test Vehicle Description Chrysler FCC and ESC Description Dilute and I/M Sample Data I/M Sample Data I/M Prolonged Idle Test Data ------- • /•'.:' ro;•.-.!• vr-.;- T ;.;:.-.••;.,..<•.: ].'W ].: i.-i-sf. HC, CO T>.-:il;: Sheet 'i c:i:!>n J •:.! .:\>'1.'.•: ^ Location.: UrH.o : Vehicle: n;>5jc.!.ine. Other: Attachment 1 CO CO!' • Hood closed, fan oTf Xran :;r.ii 5; K i.on-n e ' ; t rn \ AFTER HWFF/f Ilood clo?ecl, • fan off Traus ID if. s ion-nt'.u t r a 1 AFTP.R NYCH HooiJ closed, fan off FEDERAL 3 MODE jr. UJ.- Hooc.1 open, fan on Set; 13.7 on thunihwb(;al 52 ni'H-mrix 3 min. Set 6.4 IMP '51 25 MTU ^^7.itll I'cuiuent 25 Ml'Il-raax 3 nin. Iflle (Drive) Idle (Neutral) LOADED 2 MODF. X.uJ . = I Hood open, fan en Set dyno at f 7. 3 l or on Pendent ac 30 -MPH 30 MPH Idle (Neutral) TWO SPI:ED IDLE CYCLE Hood closed, fan off Idle (Neutral) Increase Idle spoed to 2500 + 100 1-PM Idle (HouLi-al) f . ' A^RllEVlATril I/M 1}^}:. CYCLE Hood clonocl, fan off Idle GO ?'o:'iontr.ry rev. to 2.100 RPM Idle (M) ------- lie: CO CO-IT1'NTS ur "~~'TI ra.'EiiAL iruEE *;om; jr.u1. - Hood open, f;m on Sot ''). 7 on Thniiil'n/iJ'jo.l. 52 Mi'!!- "/ax 3 niin. Sst 6..'} IUPC25 MPii u it'll PondcMit 25 Ml'H-Max 3 rcin. Idle (Hrive) Idle (Neutral) RI:PEAT LOADED T'.JO MODE x.ux -175-0i Hood open, fan on Set 'Jy.>o nr 17.3 or on Pendent at 30 TTH 30 MPII Idle (Keutral) REPEAT TWO SPEED IDLE CYCLE Eood closed, fan off Idle (Neutral) Incrr-.asc Idle Speed to 2500 + 100 KPM Idle (Neutral) }V'~"V. ABBREVIATED I/M CYCLE Hood closed, fan off Idle (Neutral) Momentary rev. to 2500 RPM Idle (Neutral) PROLONGED IDLE CYCLE Hood closed, fan off Idle (Neutral) Minutes 0 1 2 3 <4 5 6 7 8 9 10 ------- Attachment 2 Test Vehicle Description Model Year Make Emission Control System Engine Type Bore x Stroke Displacement Rated Horsepower Transmission Axle Ratio Chassis Type Tire Size Inertia Weight VIN AHP 40% Fuel Tank Volume 1979 Dodge Aspen EGR, AI, OC, 3-Way, Closed Loop Otto Spark 3.40 x 4.12 inches 225 CID 101 hp A-3 2.94 Sedan D78xl4 3500 Ibs. B103 13.5 7.20 ------- Clinics Service & Parts Division (TVQ SERVICE Of lnt«**t 3 General Manager D Sales Manager D Service-Manager D Parts Manager CD Service Technicians A new concept in controlling exhaust emissions has been incorporated in production. The new system is called the Electronic Feedback Carburetor Concept. A unique feature is the use of the Electronic Spark Control for the first time on six-cylinder engines. Both systems work together as the combustion computer controlling ignition timing and air-fuel ratios in the carburetor. The precise control of air-fuel ratio has permitted a three-way catalyst to be used in this system to. simultaneously reduce all three major exhaust pollutants; hydrocarbons, carbon monoxide, and oxides of nitrogens. The attached information provides a complete detailed description of the system, diagnosis, and service procedures. Testing procedures and specifications for the Electronic Spark Control portion are out- lined in the 1979 Service Manual. POLICY: Information Only J. W. Farley C/ Manager - Service Planning Models 1979 Volare/As] Equipped With 225-1BBL and California Emissions Package Subject Electronic Feedback Carburetor (EF» Index • FUEL Date: April 30, 1979 No. 14-05-79 P-2518-C CHRYSLER CORPORATION (THIS BULLETIN IS SUPPLIED AS TECHNICAL INFORMATION ONLY AND IS NOT AN AUTHORIZATION . FOR REPAIRS) REPRINT OF THIS MATERIAL NOT AUTHORIZED UNLESS APPROVED. niRYS!.i;K Dodge ------- No. 14-05-79 - 1 - FEEDBACK CARBURETOR CONTROLLER FEEDBACK CARBURETOR OXYGEN SENSOR REGULATOR VALVE MANIFOLD VACUUM ELECTRONIC FEEDBACK CARBURETOR CONCEPT ------- 14-05-79 - 2 - ELECTRONIC FEEDBACK CARBURETOR (EFC) SYSTEM '. The EFC system is essentially an emissions control system (Figure 1) which utilizes an electronic signal generated by an exhaust gas oxygen sensor to control, precisely, the carburetor air-fuel mixture ratio. This in turn allows the engine to produce exhaust gases of the proper composition to permit the use of a three-way catalyst, a device which can convert all three types of pollutants -- hydrocarbons (EC), carbon monoxide (CO), and oxides of nitrogen (NOx) — into harmless substances. SYSTEM COMPONENTS AND DESCRIPTION The major components of the EFC system are as follows: o Dual Catalytic Converters Oxidation catalyst 3-way catalyst o Oxygen Sensor o Mileage Counter o Combustion Computer o Feedback Carburetor o Solenoid-Operated Vacuum Regulator Valve Dual Catalytic Converters Catalytic converters are devices which decrease HC and CO emissions, or NOx emissions, or all three of these exhaust pollutants. They are muffler-like in appearance and are mounted on the underside of a vehicle as part of the exhaust system. Two converters, mounted in tandem, are used with the EFC system (Figure 2). ------- No. 14-05-79 - 3 - OXIDATION CATALYST THREE-WAY CATALYST MUFFLER CATALYTIC CONVERTERS Oxidation Catalyst: The oxidizing catalytic converter contains a platinum-coated, ceramic, honeycombed structure. Through a complex chemical reaction, the platinum stimulates the oxidation (burning) of hydrocarbons and carbon monoxide and converts them to harmless carbon dioxide and water vapor. Effective operation of this type of catalyst requires temper- atures of 600°F (315°C) or higher as well as an adequate supply of oxygen in the exhaust gas. Oxidation catalysts in current use will normally "light off" (start oxidizing) within two minutes after the first start of a cold engine. Three-way Catalyst; Research scientists and catalyst supplier companies determined that by adding rhodium, a rare and costly "noble" metal, the oxidizing converter could also "reduce", or separate, oxides of nitrogen into nitrogen and oxygen, basic components of pure air. This reducing action provides inherently better exhaust emissions control that was obtainable using only exhaust gas reci'rculation, an oxidation catalyst. ------- No. 14-05-79 - 4 - or engine modification techniques. Its use also allows richer air-fuel mixtures, more spark advance, and less '•xhaust gas recirculation — which collectively improve both drivcability and fuel economy. Effective catalytic control of all three pollutants is possible when the correct balance of excess CO is reached icr reduction and excess oxygen is reached for oxidation. It is necessary, therefore, to maintain precise control of the air-fuel mixture entering the engine, keeping it very close to the stoichiometric level (chemically correct for theoretically complete combustion). Figure 3 shows the characteristics of a three-way catalyst. The curve of efficiency as a function of air-fuel indicates that when the air-fuel ratio is lean (excess of oxygen), the control of HC and CO is very good, but control of NOx is poor. On the other hand, when the air-fuel mixture is rich (deficiency of oxygen), the control of NOx is very good but control of HC and CO is poor. At the chemically correct mixture, a narrow window exists where the control of all three pollutants is quite good. Maintaining the exhaust constituents at this precise value at which the three-way catalyst is most effective is the purpose of the EFC closed loop system. 100-1 13:1 14:1 15:1 AIR — FUEL RATIO 16:1 CHARACTERISTIC CONVERSION EFFICIENCIES THREE-WAY CATALYST ------- No. 14-05-79 - 5 - A downstream oxidation catalyst with oxygen supplied by an air pump is used to clean up the remaining HC and CO left after the exhaust gases have passed through the three-way catalytic converter. Oxygen Sensor If the air-fuel mixture is just a fraction above or below the ideal ratio, the composition of exhaust by-products will be altered, impairing the efficiency of the three-way catalyst. To provide the EFC system with an indication of the exhaust gas composition, an oxygen sensor (Figure 4) is threaded into the exhaust manifold where it is directly in the exhaust gas stream. The sensor is a sophisticated device supersensitive to the presence of oxygen. This sensitivity to oxygen is crucial. With an oxygen deficiency in the exhaust gas, outside oxygen diffuses through the sensor, acting as an electrolyte and generating a voltage. ZIRCONUM DIOXIDE BODY PROTECTING SHIELD SHELL INTERNAL AND EXTERNAL SURFACES PLATINUM PLATED HOUSING OXYGEN SENSOR The oxygen sensor is essentially a galvanic battery consisting of a cylindrical electrolyte element of zirconium dioxide which is coated inside and out with platinum. The outer platinum electrode is exposed to the hot exhaust gases while the inner platinum electrode is exposed to the atmosphere (Figure 5). A porous ceramic (spinel) coating protects the fragile platinum against damage. ------- No. 14-05-79 6 ~ GASTIGHT ELECTRICALLY CONDUCTIVE SEAL AIR EXHAUST GASES HOUSING ZIRCONIUM DIOXIDE ELECTROLYTE SPINEL COATING PLATINUM INNER ELECTRODE PLATINUM OUTER ELECTRODE OXYGEN SENSOR ELEMENT — SCHEMATIC 900- 800- 700- 600- I 500- LU CD 400- o > 300- 200- 100- 0 13:1 LEAN) V 14:1 15:1 16:1 AIR — FUEL RATIO CHARACTERISTIC OXYGEN SENSOR OUTPUT VOLTAGE CURVE ------- No. 14-05-79 - 7 - When heated to operating temperature by the hot exhaust gases, the sensor will generate a voltage. When the oxygen content is high (lean mixture), it puts out a low voltage. When the oxygen content is low (rich mixture), the voltage output is high (Figure 6). This relationship between available oxygen and sensor output voltage causes the sensor to function as a rich-lean switch. The sensor output voltage is used by the Feedback Carburetor Controller to calculate and adjust the air-fuel mixture as needed for optimum catalytic converter efficiency. The sensor's internal impedance, output voltage, and time response are all functions of temperature. This temperature- dependency is .an important consideration during cold starts and other low-temperature operating modes. In addition to the spinel coating which protects the sensor's platinum-coated outer electrode from exhaust gas erosion, a metal shield, louvered to admit exhaust gases, protects the fragile zirconium dioxide body from abrasion by exhaust parti- culates and from breakage during handling. In order to ensure good air-fuel ratio control over the life of the vehicle, the sensor must be changed at 15,000* mile (24 000 km) intervals. 15,000 MILE REMINDER LIGHT SPEEDOMETER - ODOME7 RUBBER SHIELD SPEEDOMETER CABLE MILEAGE COUNTER ------- No. 14-05-79 ~ 8 '•'. 11 o gc«; Cou r. t e r A mileage counter (Figure 7) in-line with the speedometer is used to'indicate when to replace the oxygen sensor. When lo.OOO .r.iles (24 000 km) have elapsed, the counter will actuate an' "EFc' SYSTEM" instrument panel light. The counter can be reset at the time the sensor is replaced. ELECTRONIC SPARK CONTROL COMPUTER HOUSING FEEDBACK CARaU.RETOR COrJTROLLER COMBUSTION COMPUTER ------- No. 14-05-79 ~ 9 Combustion Computer with Feedback Carburetor Controller The Combustion Computer on the air cleaner houses both the Electronic Spark Control Computer and the Feedback Carbu- retor Controller (Figure 8). The electronic spark control computer interfaces with the feedback carburetor controller and provides optimum engine ignition timing through electronic control of the spark advance. The feedback carburetor controller is the information processing component of the EFC system. It monitors the voltage generated by the oxygen sensor and receives input signals from sensors reporting engine coolant temperature, manifold vacuum, engine rpm, and engine starting. The controller interprets the various inputs and then transmits the proper output signal to the solenoid-operated vacuum regulator valve, which in turn forwards a signal to the carburetor. Feedback Carburetor A single barrel feedback carburetor is used to maintain the air-fuel ratio within the limits required for efficient catalysis in the three-way catalyst. The vacuum signal acts simultaneously on two diaphragms (Figure 9), one for controlling the idle system and the other for controlling the main metering system. The diaphragms control tapered rods which vary the size of orifices to adjust the idle system air bleed and the main metering system fuel flow. These variable controls complement and are used in parallel with a fixed idle air bleed and main fuel metering jet. A "lean" command from the Feedback Carburetor Controller to the vacuum regulator will result in an increasing vacuum level to the carburetor. This will cause the diaphragm to move the idle air bleed rod upward in its orifice causing increased idle air bleed. Simultaneously, the other diaphragm will move the main metering rod upward in its orifice causing reduced fuel flow. The result from both circuits is a leaner air-to-fuel ratio. On the other hand, a "rich" command will result in a lower vacuum level to the carburetor which will cause the spring- loaded rods to move in the opposite direction and furnish a richer mixture. The range of mixture control is approximately 4 air-to-fuel ratios, 2 rich and 2 lean, or 14.7 (± 2.0) to 1. The carburetor is calibrated so that the desired nominal flow is obtained with a vacuum signal of 2.5 inches Hg (8.5 kPa). Other features of the feedback carburetor include ------- No. 14-05-79 - 10 - o A throttle-actuated wide-open-throttle enrichment valve (not shown) o An idle mixture screw, concealed within the throttle body to prevent tampering o A separate nipple on the throttle body to serve as a source for the air pump diverter valve vacuum signal. FIXED IDLE AIR BLEED FEEDBACK CONTROLLED IDLE AIR BLEED VACUUM CHANNEL FUEL BOWL FEEDBACK CONTROLLED MAIN SYSTEM FUEL RESTRICTOR , CONCEALED IDLE ADJUSTMENT SCREW MAIN METERING JET FEEDBACK CARBURETOR ------- No. 14-05-79 ~ 11 VENT PORT ARMATURE RETURN SPRING VENT r SOLENOID ^ OUTPUT TO CARBURETOR VACUUM INPUT (MANIFOLD VACUUM) REGULATED VACUUM , VACUUM REGULATOR SOLENOID-VACUUM REGULATOR VALVE Solenoid-Operated Vacuum Regulator Valve A solenoid-operated vacuum regulator valve (Figure 10) con- verts the electrical signal from the Feedback Carburetor Controller to a vacuum signal to control the carburetor in maintaining the air-fuel ratio at stoichiometric (14.7:1). Intake manifold vacuum is supplied to the regulator at the lower port, and a regulated 5 inches of mercury (Kg)(17 kPa) is generated within the device. The armature in the electric solenoid at the top of the unit is fitted with a conical tip at each end and functions as a valve. When there is no electrical signal to the solenoid, the spring-loaded armature is held downward as shown to block off the port to the regulated vacuum and open the vent port to atmosphere. When the solenoid is energized, the armature rises off its seat allowing the regulated vacuum signal to pass to the carburetor while simul- taneously closing the vent port. The carburetor.control vacuum signal can be regulated between 0 and 5 inches Hg by .varying ------- No. 14-05-79 - 12 - the length of time the armature rests in the on (full 5 inches Hg (17 kPa) vacuum) or off (0 inches Kg (0 kPa) vacuum) position. The rapid up-down motion of the armature determines the average vacuum supplied to the carburetor. Control of the ratio of time "on" to time "off" is deter- mined by the feedback carburetor controller through the electrical signal to the solenoid. SYSTEM OPERATION Purpose As was seen earlier (Figure 3), a three-way catalyst is most efficient in controlling HC and CO when the air-to fuel ratio is leanest and there is an excess of oxygen; however, under this condition, control of NOx is poor. On the other hand, when the air-to-fuel ratio is rich and there is a deficiency of oxygen, the control of NOx is good but control of HC and CO is poor. At the chemically correct mixture, a narrow "window" exists about the stoichiometric region (14.7:1 air- to-fuel ratio) where the control of all three pollutants is quite good. Maintaining the exhaust constituents at this precise value at which the three-way catalytic converter is most effective is the purpose of the EFC system. Operating Modes The EFC system can operate in two distinct modes, open loop and closed loop. During closed loop operation, the system is responsive to exhaust gas oxygen levels as indicated by the oxygen sensor. In the open loop mode, the system operates in response to preprogrammed electronic commands and signals other than those from the oxygen sensor. Closed'Loop Operation In the closed loop mode, the feedback system is operational and continuously corrects the air-to-fuel ratio toward a stoichiometric mixture. Figure 11 shews a block diagram of sensing and actuating elements that interact to form a loop. Each component is sensitive to the performance of the upstream component and responds by communicating to the down-stream component. Closed loop operation will not begin until the engine coolant temperature reaches 150°F (66°C). This permits the oxygen sensor and three-way catalyst to warm to operating temperatures. ------- No. 14-05-79 - 13 - AIR INTAKE I ENGINE I RPM ESC COMPUTER EFC CONTROLLER COMBUSTION COMPUTER EFC SYSTEM BLOCK DIAGRAM At exhaust temperatures over 660°F {350°C), the zirconium dioxide electrolyte allows the passage of oxygen ions from one electrode to the other while blocking the passage of others. The resulting oxygen pressure differential produces a voltage output signal that varies in strength depending on the relative availability of oxygen. The sensor has the unique property of producing an abrupt •change in voltage output precisely when the supply of exhaust gas oxygen departs from the stoichiometric (14.7 tol) air-to- fuel ratio necessary for optimum three-way catalyst efficiency (Figure 6). Because of this characteristic, the sensor output voltage can be used as an indication of when the system is operating richer or leaner than desired. When the exhaust gas oxygen content is low, as it would be with a rich mixture, the voltage output will be high, indicating a leaner mixture is required. Similarly, a voltage output that is low means the oxygen content is too high and that a richer- mixture is needed. Thus, the EFC system does not run at a constant 14.7 to 1 air-to-fuel ratio, but fluctuates closely about it. It constantly corrects to stoichiometric by monitoring sensor voltage signals and issuing "rich" or "lean" commands to drive the system to stoichiometry. ------- No. 14-05-79 - 14 - The output voltages from the sensor are evaluated by the controller along with signals from the other system sensors. This processing results in an electrical output signal to the solenoid-vacuum regulator valve. By rapid switching of the solenoid and control of the relative "on" to "off" time, vacuum levels between 0 and 5 inches Hg (17 kPa) can be provided as control vacuum to the carburetor. Figure 12 provides two examples of the chain of events that occurs continuously to drive the air-to-fuel ratio toward a stoi- chiometric mixture. . An added benefit of the EFC system is its built-in ability to maintain mixture constant at varying altitudes, eliminating the mixture enrichment which normally occurs when a car is driven to higher altitudes. ENGINE OPERATING— •- CONDITION RICH OF STOICHIOMETRY EXHAUST GAS OXYGEN HIGH OUTPUT . VOLTAGE (>.4 VOLT) FEEDBACK — CARBURETOR— •- CONTROLLER DIRECTS VAC. SOL.-REG. TO GREATER "ON" TIME SOLENOID VACUUM .. REGULATOR VALVE INCREASED DUTY CYCLE RESULTS IN HIGHER OUTPUT VACUUM VACUUM SIGNAL TO FEEDBACK CARBURETOR INCREASING SIGNAL PULLS DIAPHRAGMS UPWARD POSITION — — OF IDLE -1 DIAPHRAGM HIGHER POSITION FOR INCREASE IN AIR BLEED (INCREASES ORIFICE) POSITION .._ OF MAIN m CVCTCU ™""'^ DIAPHRAGM HIGHER POSITION FOR DECREASE IN FUEL FLOW (DECREASES ORIFICE) RESULTANT CORRECTIONS TOWARD LEAN LEAN LOW DIRECTS DECREASED DECREASING SIGNAL LOWER POSITION LOWER POSITION TOWARD RICH OF STOICHIOMETRY OUTPUT VOLTAGE ((.4 VOLT) VAC. SOL.-REG. TO LESS "ON" TIME DUTY CYCLE RESULTS IN LOWER OUTPUT VACUUM ALLOWS DIAPHRAGM SPRINGS TO MOVE DIAPHRAGMS DOWNWARD FOR DECREASE IN AIR BLEED (DECREASES ORIFICE) FOR INCREASE IN FUEL FLOW (INCREASES ORIFICE) Oj SENSOR OUTPUT RICH •LEAN RPM MANIFOLD J VACUUM 3 DUTY CYCLE AIR- TEMP CLOSED LOOP OPERATING SEQUENCE Open Loop Operation The Feedback Carburetor Controller also directs operation of the EFC system during periods when the air-fuel ratio informa- tion from the oxygen sensor is interrupted (open loop modes). This occurs under any of the following conditions, as explained below. ------- No. 14-05-79 - 15 - o Coolant temperature below 150°F (66°C) o Oxygen sensor temperature below 660°F (350°C) o Low manifold vacuum o Oxygen sensor default o Hot engine starting During start-up and acceleration, the controller is programmed to ignore signals from the oxygen sensor, allowing the carbu- retor to produce temporarily richer mixtures for good performance. When the engine is warming up, the air injection system supplies air to the exhaust manifold — upstream of both catalytic con- verters — to provide extra oxygen for more complete burning within the catalytic converter of hydrocarbons and carbon monoxide emissions that tend to develop at lower operating temperatures. (NOx is not a problem at this time since oxides of nitrogen develop only at higher combustion temperatures). This extra burning raises temperatures within the exhaust system and causes the oxygen sensor and three-way catalyst to warm up faster." During this period, the three-way catalytic converter functions as an oxidation catalyst. After the engine is warmed up and oxygen sensor and catalyst operating temperatures are reached, an air switching valve diverts air flow from the exhaust ports to enter the exhaust downstream from the three-way catalyst and just ahead of the oxidation catalyst. At this point, the exhaust is hot enough to oxidize the unburned HC and CO. Again, the addi- tion of injected air is required in the oxidation process. Low-Vacuum Sensor: Upon acceleration with a cold engine, if the throttle is open sufficiently so that manifold vacuum drops below 4.5 inches Hg (15 kPa), a vacuum signal will be supplied to the Feedback Carburetor Controller which will enrich the air-fuel mixture even further to prevent engine stalls, sags, or stumbling and enhance driveability. After the engine -has warmed'up and the system is under the control of the oxygen sensor (closed loop mode), the system will revert to the open loop mode whenever the manifold vacuum drops below 3 inches Hg (10 kPa). This signal is to assure a sufficiently-rich mixture for power and performance when accelerating from cruising speeds. After acceleration, manifold vacuum will return to a higher level and closed loop operation will resume. Different vacuum signal values are used during open and closed loop modes because less enrichment is required for acceleration when fully warmed up than for acceleration during warm-up. ------- No. 14-05-79 ~ 16 - Coolant Temperature Sensing Switch: A coolant temperature sensing switch, located in the cylinder head, electrical circuit to the Feedback Carburetor Controller when engine coolant reaches a temperature of 150°F (66°C). At this point, the oxygen sensor is sufficiently warm to start functioning. When this occurs, operation begins in response to signals from the sensor. Open loop operation terminates when there is sufficient vacuum and the engine coolant and oxygen sensor are at their proper operating temperatures. It may happen, however, under pro- longed idle at low ambient temperatures that the oxygen sensor may cool off enough so that it will not function properly. This condition will be detected electronically from the sensor and the system will compensate accordingly until the sensor is again warm. The sensor will warm up very quickly once the car is accelerated away from idle. ------- No. 14-05-79 - 17 - DIAGNOSTICS The following test equipment is needed for diagnosis of the EFC system: o Vacuum gauge - 0-5" Hg (accurate within t 1/2" in that range) o Vacuum gauge - 0-30" Hg o Hand pump with vacuum gauge o Two short length of 3/16" I.D. vacuum tubing o Two 3/16" tee o Jumper wire (approximately 5 feet) In general a malfunction of the EF.C system can be diagnosed by observing the action of a vacuum gauge connected so as to observe the control vacuum from the solenoid-regulator to the carburetor. A malfunction of the EFC system can cause such problems as: o Surge o Hesitation o Rough Idle o Poor Fuel Economy The following checks should be made prior to performing any diagnostic tests: o Check all vacuum hoses for proper hook up. (Refer to hose routing label located underhood) and for kinks or other damage. o Check all electrical connections and for frayed, cracked or broken wiring. Refer to wiring diagram. o Check the intake and exhaust manifolds for leakage. ------- No. 14-05-79 - 18 - Determining the Problem With the vehicle fully warmed-up, the 0-5" Hg vacuum gauge is teed into the control vacuum signal to the carburetor. The vehicle is started and allowed to idle while the vacuum gauge is observed. The gauge should indicate a steady 2.5" Hg reading for approximately 100 seconds after starting, drop to 0", and then gradually rise to between 1.0 and 4.0" Hg average. The reading will oscillate about + 0.5" Hg. If the gauge does not indicate in the above area, the engine speed should be raised to approximately 2000 rpm and the reading observed again. If the reading is between 1.0 and 4.0" Hg, the engine should be returned to idle to determine if the reading there is now between 1.0 and 4.0" Hg. If the reading at idle is within the proper range, it indicates the oxygen sensor was not fully warmed originally and the system is operating properly and other areas should be checked to resolve the complaint. If the gauge reads in the proper range at 2000 rpm and does not at idle, it means the idle mixture is out of adjustment and the carburetor must be replaced. The following procedures should be undertaken to determine the cause of the problem if the control vacuum is above 4" Hg or below 1.0" Hg. It should be noted that for most system malfunction conditions the control vacuum is typically at either 0" Hg or 5" Hg. CONTROL VACUUM ABOVE 4" Ha If in the previous tests the control vacuum was consistently above 4" Hg, the problem could be found in the following components: o Carburetor o Carburetor Heat Shield o Solenoid - Regulator r o Combustion Computer o Oxygen Sensor ------- No. 14-05-79 - 19 - The engine is started and with the transmission in Neutral, the throttle is placed on the next to the lowest step of the fast idle cam. The following steps are then taken to deter- mine the cause of the problem. STEP 1 •» • • • Carburetor Since a high control vacuum indicates:that the system is trying to correct for a rich mixture, the following test should be made to determine if the mixture, is in fact too rich. Remove the PCV hose from the PCV valve and cover the end with your thumb. Gradually uncover the end of the hose until the engine begins running roughly indicating a very lean mixture. If the control vacuum to the carburetor gradu- ally gets lower as more of the PCV hose is uncovered, it indicates the carburetor was too rich and the carburetor should be replaced; however, step 2 should be completed before the carburetor is replaced. If the control vacuum remains high, the problem is in another area of the system. STEP 2 Carburetor Heat Shield Prior to replacing the carburetor as indicated by Step 1, an inspection should be made to determine if an interference exists between the carburetor heat shield and the mechanical power enrichment valve actuating lever at the rear of the carburetor. If there is an interference, it will cause the carburetor to be too rich. A new heat shield has been released for 1979 model year. This was done to provide clearance for the mechanical power enrichment lever and the throttle position transducer actuating lever. The earlier heat shield is not recommended but could be used if modified for clearance. STEP 3 Solenoid - Regulator Disconnect the electrical connector to the device. The control vacuum to the carburetor should drop to zero. If it does not, replace the solenoid - regulator. ------- No. 14-05-79 - 20 - STEP 4 Combustion Computer Disconnect the oxygen sensor wire and with a jumper wire connect the harness lead to the battery negative terminal. CAUTION: DO NOT CONNECT THE WIRE FROM THE OXYGEN SENSOR TO BATTERY OR GROUND. The control vacuum should gradually lower to 0" in about 15 seconds. If it does not, replace the computer. If it does, replace the oxygen sensor. NOTE: Prior to replacing computer or sensor, make sure wire between the two is okay. CONTROL VACUUM BELOW 1.0" Hg If in the preliminary tests the control vacuum was consistently below 1.0" Hg, the problem could be found in the following areas: o Lack of vacuum to the computer vacuum transducer o Carburetor o Air switching system o Solenoid - Regulator o Wiring Harness o Combustion Computer o Oxygen Sensor STEP 1 Lack of Vacuum to Computer Vacuum Transducer, r With engine at idle Neutral, disconnect the vacuum hose at the computer transducer and connect the hose to a vacuum (0-30" Hg) gauge. The gauge should .read manifold vacuum (in excess of 12" Hg) If it does not, trace the hose to its source•and then connect it properly (to a source of manifold vacuum)* The remaining steps should be performed with the transmission in Neutral and the throttle on the next to the lowest step of the fast idle cam, parking brake applied. ------- No. 14-05-79 - 21 - STEP 2 Carburetor Since a low control vacuum is indicative of the system trying to correct for a lean mixture, the following test should be made to determine if the mixture is in fact too lean. The air cleaner cover is removed and the choke blade is gradually closed until the engine begins running roughly thus indicating a very rich mixture. If the control vacuum to the carburetor gradually increases to 5" Hg as the choke is closed, it indicates either the carburetor was too lean or the air switching system was not functioning properly (go to Step 3). • If the control vacuum remains low, it indicates the problem is in another area of the system (go to Step 4). STEP 3 Air Switching System Disconnect the air injection hose at the metal tube that leads to the rear of the cylinder head and plug the tube. If the control vacuum remains below 1.0" Hg, replace the carburetor. If the control vacuum returns to the proper range, reconnect the air injection hose and disconnect the 3/16" vacuum hose from the air switching valve. If the control vacuum remains below 1.0" Hg, replace the air switching valve. If the control vacuum returns to the proper range, check the vacuum hose routings for proper connections and if the connections are correct, replace the vacuum coolant switch (CCVES). STEP 4 Solenoid - Regulator Before testing the solenoid - regulator, verify that the bottom nipple is connected to the manifold vacuum. Disconnect the electrical connector to the solenoid - regu- lator. Connect a jumper wire from the positive terminal of the battery to one terminal of the solenoid - regulator lead. Connect the other terminal of the solenoid - regulator lead to ground. The control vacuum should go above 5" Hg. If it does not, replace the solenoid - regulator. If it does, go to Step 5. ------- No. 14-05-79 22 - STEP 5 Wiring Harness Disconnect the 5-way connector at the computer. Connect a jumper wire from terminal 2 in harness to ground. The control vacuum should go to 5" Hg. If it does not, trace the wire back to the battery to find where the voltage is lost. If it does, go to Step 6. O •MI 2 © ^ 5 NOTE: Almost all problems associated with the wiring harness will be caused by the connectors. Make sure connectors are firmly snapped in place and there is no corrosion or frayed wires causing poor contact. STEP 6 Combustion Computer Disconnect the oxygen sensor wire and with a jumper wire, connect the harness lead to the battery positive terminal. CAUTION: Do not connect the wire from the oxygen sensor to battery or ground. The control vacuum should gradually rise to 5" Hg in about 15 seconds. If it does not, replace the computer. If it 'does, replace the oxygen sensor. ------- No. 14-05-79 - 23 - OXYGEN SENSOR - Removal and Installation Removal Disconnect battery cable, remove air cleaner. Disconnect oxygen sensor connector. Remove sensor using Special Tool C-4589. Inspection Inspect wire and connector for signs of degradation. If insulation is frayed to extent that connector or terminal is visible, replace sensor. Inspect water splash shield which is a metal band running around the upper portion (sleeve) of the sensor and covers the vent holes. If splash shield is not intact, replace sensor. Installation Coat threads of sensor with a nickel base anti-sieze compound such as Loctite LO-607 or Never Seez NSN, or equivalent. Do not use graphite or other type compounds as these could electrically insulate the sensor from the manifold. Start sensor by hand and torque to (35 + 5 foot-pounds) using Special Tool C-4589. Install air cleaner assembly. Recon- nect battery cable. ------- No. 14-05-79 - 25 - CARBURETOR SPECIFICATIONS Accelerator Pump 1-3/4" Dry Float Setting (± 1/32") Flush with top of bowl cover gasket Bowl Vent 1/16" Vacuum Kick .150" Fast Idle Cam .080" Choke Unloader .250" Basic Timing 15° BTDC Idle set speed 750 Fast Idle Speed 1800 ------- No. 14-05-79 ~ 24 " IGNITION TIMING PROCEDURE 1. Ground the carburetor switch with a jumper wire. 2. Connect a suitable timing light to ignition system. 3. Start the engine. 4. Wait one minute after step 3. 5. With the engine running at a rpm not greater than the specified curb idle rpm, adjust timing to specifications, 6. Remove ground wire and timing light. CURB IDLE SET PROCEDURE* 1. Start and run engine in Neutral on the second step of the fast idle cam until thermostat is open (engine fully warmed up) and the radiator becomes hot. This may take 5-10 minutes. 2. Disconnect and plug the EGR hose at the EGR valve. 3. Ground carburetor switch with a jumper wire. 4. Adjust the idle rpm in Neutral to the curb idle rpm specification located on the Vehicle Emission Control Information Label. 5. Reconnect the EGR hose and remove jumper wire from the ground switch. *Only after timing is known to be within specification. ------- If I U LJ ELECTRIC r"7 ELECTRIC CHOKE ^-f CHOKE I (CONTROL — VACUUM REGULATOR VALVE MILEAGE SWITCH I m o i IGNITION COIL THROTTLE POSITION TRANSDUCER CONNECTOR COOLANT SENSOR CARS SWITCH SINGLE COMPUTER CONNECTOR CHANGE TEMPERATURE SWITCH TEMPERATURE GAUGE SENDING UNIT DISTRIBUTOR CONNECTOR OXYGEN SENSOR ------- No. 14-05-79 - 26 - COMPONENT IDENTIFICATION (EMISSION RELATED) ITEM Air Pump Pulley with Chrysler A/C with Sankyo A/C without A/C Air Switching/Diverter Valve Carburetor (Holley R-8286A) CCEVS Switch Choke Assembly Charge Temperature Switch Distributor EGR Vacuum Amplifier EGR Valve All except wagons Wagons Electric Choke Control Emission Control Information Label Combustion Computer Coolant Switch Spark Plugs EGR Timer Vacuum Hose Routing Label Vacuum Solenoid Vapor Canister IDENTIFICATION NUMBER* "4173221 4071720 4071720 4105053 4095909 4006587 4095336 4111482 4091490 4041732 4104009 4104008 4091036 4173883 4111373 4091719 4091678 (RBL-16Y) 4111481 4173258 3874027 3577595 *This number is located on either a label or stamped into part. It does not represent a service replacement number. Refer to the appropriate Parts Catalog for this information. ------- FTP (gms/miiu) Date 6-29- 7'J ' 7-2-79 7-3-79 7-9-79 7-10-79 7-1L-79 : 7-13-79 7 7-16-79 7 Date 6-29-79 7-2-79 7-3-79 7-9-79 7-10-79 7-11-79 7-13-79 7-16-79 Note: HC CO ^st Number HC CO i-si.H.W .40 4.5 j-8150,51 .41 3.7 9-8152,53 .34 3.3 i-8154,55 .40 1.9 •J-8156.57 .62 7.6 V-8138.59 1.03 29.8 V-8160,61 .40 3.7 •j-8162,63 .43 3.7 Test Numbers 79-8148, 49 79-8150, 51 79-8152, 53 79-8154, 55 79-8156, 57 79-8158, 59 79-8160, 61 79-8162, 63 values in ppm Hexane. C02 NOx 527 .91 518 .89 507 1.39 494 1.15 551 .60 473- .40 504 1.81 521 .89 HC/CO F.E. 16.6 16.9 17.3 17.8 15.7 17.0 17.4 16.8 HC/CO Raw HC 65 60 28 85 33 230 50 30 (ppm/%) CO HC .02 .067 .02 .070 .03 .079 .03 .066 .04 .050 2 . 09 . 082 5 .03 .057 .03 .063 Federal Three HC/CO HC/CO 52 mph 10/.02 10/.018 12/.025 10/.02 10/.15 15/.25 10/.05 10/.04 10/.02 10/.018 22/.035 10/.02 12/.15 12/.17 10/.03 10/.03 15/ 15/ 18/ 10/ 10/ 13/ 10/ 10/ 25 mph .02 15/.018 .02 12/.02 .05 22/.055 . 02 10/ . 02 .06 12/.06 .45 12/.35 .04 10/.04 .03 10/.03 met (ems/mile) CO C02 NOx .276 415.3 1.848 .286 414.6 1.967 .121 404.6 3.566 .199 408.7 2.059 .134 490.5 .725 .543 396.8 1.185 .136 419.9 5.834 .174 405.5 2.021 Mode HC/CO HC/CO Idle (Drive) 20/.01 20/.011 25/.018 20/.011 22/.04 22/.055 15/.02 25/.02 30/.04 25/.02 85/.60 175/.70 50/.05 25/.03 20/.03 18/.025 Raw (ppm/X) F.E. HC CO 21.3 55 .025 21.4 40 .02 21.9 25 .02 21.7 35 .02 18.0 18 .02 21.9 120 .7 21.1 20 .03 21.8 15 .02 HC/CO HC/CO Idle (Neutral) 30/.01 28/.016 43/.018 30/.01 22/.04 33/.055 60/.02 30/.02 35/.02 30/.02 200/.80 250/.75 80/.05 70/.04 35/.03 35/.03 NYCC (ems/mile) HC CO C02 NOx F.E. .907 4.111 831.6 .898 3.745 829.2 1.090 8.340 817.25 .889 2.996 829.17 1.084 21.013 927.65 1.838 33.818 784.3 .691 2.572 830.4 1 .644 2.959 860.6 Loaded HC/CO HC/CO 30 mph 10/.02 10/.02 11/.016 10/.017 25/.05 22/.055 10/.02 10/.02 18/.07 18/.07 18/.33 12/.25 10/.04 10/.04 10/.03 10/.03 .550 10.5 .630 10.6 .533 10.6 .726 10.6 .511 9.2 .664 10.5 .378 10.6 .748 10.2 Two Mode HC/CO Raw ppm/ Z HC CO 49 .16 90 .022 43 .016 75 .02 42 .06 250 .65 50 .04 60 .04 HC/CO Idle (Neutral) 15/.02 25/.015 20/.02 35/.02 25/.02 HO/. 55 70/.04 35/.03 30/.011 28/.014 22/.055 25/.015 30/.02 70/.50 35/.03 25/.02 Test Comments *f: B/L EGO Sen. Disc. CTS Disc. Sol. Vac. Reg. Disc. A.I. Bypassed ECR Disc. B/L B/L B/L ECO Sen. Disc. CTS Disc. Sol. Vac. Reg. Disc. A.I. Bypassed ECR Disc. B/L ------- Date Test Number 6-29-79 7-2-79 7-3-79 7-9-79 7-10-79 7-11-79 7-13-79 7-16-79 79-8148. 79-8150, 79-8152, 79-8154, 79-8156, 79-8158, 79-8160, 79-8162, 49 51 53 55 57 59 61 63 Two Speed Idle Cycle HC/CO HC/CO Neutral 40/.016 28/.015 28/.02 30/.1 30/.02 130/.55 60/.04 30/ . 03 40/.018 27/.016 38/.05 25/.02 30/.02 ISO/. 60 55/.04 30/.025 HC/CO 2500 10/.02 12/.017 22/.025 10/.02 25/.09 15/.45 10/.04 10/.03 HC/CO rpm 15/.02 12/.020 18/.04 10/.02 20/.9 15/.35 10/.04 10/.03 HC/CO HC/CO Idle (Neutral) 55/.13 22/.017 90/.03 45/.02 40/.03 140/.80 40/.03 25/.02 45/.016 20/.012 38/.04 25/.02 40/.02 80/.45 30/.03 30/.02 Abbreviated I/K Idle Cycle HC/CO HC/CO Idle (Neutral) 35/.02 30/.018 30/.03 50/.02 40/.03 140/.80 40/.03 50/.02 22/.010 42/.04 35/.02 40/.02 80/.45 30/.03 HC/CO HC/CO 25/.02 30/.02 Idle (Neiitral) Test Comments 45/.10 30/.02 B/L 22/.018 24/.010 B/L 35/.03 SO/.05 ECO Sen. Disc. 35/.02 30/.02 CTS Dls. 40/.03 40/.02 Sol. Vac. Reg.bisc. 150/-.77 90/.50 A.I. Bypassed 40/.04 30/.03 ECR Disc. 30/.03 30/.025 B/L Note: HC values In ppm Hexane. CO values In percent. Prolonged Idle Cycle HC/CO Date 6-29-79 7-2-79 7-3-79 7-9-79 7-10-79 7-11-79 7-13-79 7-!t>-79 Test Number 79-8148, 49 79-3150, 51 79-8152, 53 7-J-8154, 55 75-8156, 57 79-U158, 59 79-8160, 79-BJ62, 61 63 Int. 20/.02 20/.011 50/.05 40/.02 40/.02 100/.60 30/.03 1 30/.02 22/.017 38/.03 50/.02 35/.02 200/.65 55/.04 2 35/.02 "25/.017 44/.03 60/.02 38/.005 175/.60 60/.04 3 50/.02 35/.018 44/.03 70/.02 40/.05 225/.60 70/.04 4 55/.02 30/.018 40/.02 75/.02 40/.07 240/.55 80/.04 5 60/. •SO/. 58/. 100/. 40/. 185/. 80/. 02 018 02 02 07 55 04 6 85/.02 45/.018 58/.02 85/.02 45/.07 230/.65 100/.05 7 80/.02 SO/. 012 45/.02 110/. 02 45/.07 2 SO/. 50 110/. 05 8 70/.03 so/.o:.6 SO/. 02 80/.02 40/.03 250/.60 95/.0* 9 80/.02 50/.015 53/.02 HO/. 02 42/.09 250/.60 100/.05 10 ' 65/.02 50/.015 70/.02 95/.02 42/.09 250/.60 90/.04 B/L B/L EGO Sen. Disc. CTS Disc. Sol. Vac. Reg. Disc. A.I. Bypassed EGR Disc. 30/.025 30/.03 40/.04 45/.04 65/.04 60/.04 60/.04 75/.04 90/.0.i 100/.045 100/.045 B/L 3- a * US. GOVERNMENT PRINTING OFFICE: 1979- 651-112/0070 ------- |