druhl Posted October 31, 2004 Report Share Posted October 31, 2004 I have been trying to get my STS inspected for over a month now without success. I have the same monitors incomplete. I have oxygen heaters monitor system incomplete, oxygen sensor monitor incomplete and the catslyst monitor incomplete. The state lets me have two systems incomplete and I have three so it will not pass inspection and it is the last day of the month. I have changed the following parts , catalyatic converter , and the pre & post converter oxygen sensors. The system seems to be working fine with many test drives connected to a scan tool looking at all four oxygen sensor graphs. I need an expert that knows this system well. Please help. Link to comment Share on other sites More sharing options...
Logan Posted October 31, 2004 Report Share Posted October 31, 2004 Powertrain Control Module Emissions and OBD II System Status and Drive Cycle For Satisfying the Federal Inspection/Maintenance (I/M 240) Regulations The system status selection is included in the scan tool System Info menu. Several states require that the I/M 240 (OBD ll system) pass on-board tests for the major diagnostics prior to having a vehicle emission inspection. This is also a requirement to renew license plates in some areas. Using a scan tool, the technician can observe the system status, complete or not complete, in order to verify that the vehicle meets the criteria which complies with local area requirements. Using the system status display, any of the following systems or a combination of the systems may be monitored for I/M readiness: The catalyst The HO2S The HO2S heater Important The system status display indicates only whether or not the test has been completed. The system status display does not necessarily mean that the test has passed. If a Failed Last Test indication is present for a DTC associated with one of the above systems, that test is failed. Diagnosis and repair is necessary in order to meet the I/M 240 requirement. Verify that the vehicle passes all of the diagnostic tests associated with the displayed system status prior to returning the vehicle to the customer. Refer to the Typical OBD II Drive Cycle table to use as a guide to complete the I/M 240 system status tests. More than one drive cycle may be needed. Following a DTC info clear, the system status will clear only for the systems affected by any DTCs stored. Following a battery disconnect or a control module replacement, all of the system status information will clear. Typical OBD II Drive Cycle Diagnostic Time Schedule for I/M Readiness Vehicle Drive Status What is Monitored? Cold Start, coolant temperature less than 50°C (122°F) -- Idle 2.5 minutes in Drive (Auto) Neutral (Man), A/C and rear defogger ON HO2S Heater, Misfire, Secondary Air, Fuel Trim, EVAP Purge A/C off, accelerate to 90 km/h (55 mph), 1/2 throttle. Misfire, Fuel Trim, Purge 3 minutes of Steady State - Cruise at 90 km/h (55 mph) Misfire, EGR, Secondary Air, Fuel Trim, HO2S, EVAP Purge Clutch engaged (Man), no braking, decelerate to 32 km/h (20 mph) EGR, Fuel Trim, EVAP Purge Accelerate to 90-97 km/h (55-60 mph), 3/4 throttle Misfire, Fuel Trim, EVAP Purge 5 minutes of Steady State Cruise at 90-97 km/h (55-60 mph) Catalyst Monitor, Misfire, EGR, Fuel Trim, HO2S, EVAP Purge Decelerate, no breaking. End of Drive Cycle EGR, EVAP Purge Total time of OBD II Drive Cycle 12 minutes -- Primary System Based Diagnostics There are primary system-based diagnostics which evaluate the system operation and their effect on vehicle emissions. The primary system-based diagnostics are listed below, with a brief description of the diagnostic functionality. Oxygen Sensor Diagnosis Diagnose the Fuel Control Heated Oxygen Sensors (Bank 1 HO2S 1 and Bank 2 HO2S 1) for the following conditions: Heater Performance (time to activity on cold start) Slow Response Response Time (time to switch R/L or L/R) Inactive Signal (output steady at bias voltage - approximately 450 mV) Signal Fixed High Signal Fixed Low Diagnose the Catalyst Monitor Heated Oxygen Sensors (Bank 1 HO2S 2 and Bank 1 HO2S 3) for the following functions: Heater Performance (time to activity on cold start) Slow Response Response Time (time to switch R/L or L/R) Signal fixed low during steady state conditions or power enrichment (hard acceleration when a rich mixture should be indicated) Signal fixed high during steady state conditions or decel fuel mode (deceleration when a lean mixture should be indicated) Inactive Sensor (output steady at approximately 438 mV) Fuel Control Heated Oxygen Sensors (Bank 1, HO2S 1) (Bank 2, HO2S 1) The main function of the fuel control heated oxygen sensor is to provide the control module with exhaust stream information in order to allow proper fueling and maintain emissions within the mandated levels. After the sensor reaches the operating temperature, the sensor generates a voltage inversely proportional to the amount of oxygen present in the exhaust gases. The control module uses the signal voltage from the fuel control heated oxygen sensors in a closed loop in order to adjust the fuel injector pulse width. While in a closed loop, the Control Module can adjust fuel delivery in order to maintain an air to fuel ratio which allows the best combination of emission control and driveability. If the oxygen sensor pigtail wiring, connector or terminal are damaged, replace the entire oxygen sensor assembly. Do not attempt to repair the wiring, connector, or terminals. In order for the sensor to function properly, the sensor must have a clean air reference provided to it. This clean air reference is obtained by way of the oxygen sensor wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference. Any attempt to repair the wires, connectors or terminals could degrade oxygen sensor performance. Catalyst Monitor Heated Oxygen Sensors (Bank 1 HO2S 2 and Bank 1 Sensor 3) In order to control emissions of Hydrocarbons (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx), the system uses a three-way catalytic converter. The catalyst within the converter promotes a chemical reaction which oxidizes the HC and CO present in the exhaust gas, converting them into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting it to nitrogen. The Control Module has the ability to monitor this process using the Bank 1 HO2S 2 and the Bank 1 HO2S 3 heated oxygen sensors. The Bank 1 HO2S 2 sensor produces an output signal which indicates the amount of oxygen present in the exhaust gas entering the three-way catalytic converter. The Bank 1 HO2S 3 sensor produces an output signal which indicates the oxygen storage capacity of the catalyst; this in turn indicates the catalyst's ability to convert exhaust gases efficiently. If the catalyst is operating efficiently, the Bank 1 HO2S 2 signal will be far more active than that produced by the Bank 1 HO2S 3 sensor. In addition to catalyst monitoring, the Bank 1 HO2S 3 heated oxygen sensor has a limited role in controlling fuel delivery. If the Bank 1 HO2S 3 signal indicates a high or low oxygen content for an extended period of time while in a closed loop, the Control Module adjusts the fuel delivery slightly in order to compensate. Catalyst Monitor Diagnostic Operation The OBD II catalyst monitor diagnostic measures oxygen storage capacity. In order to do this, the heated sensors are installed before and after the Three-Way Catalyst (TWC). Voltage variations between the sensors allow the control module to determine the catalyst emission performance. As a catalyst becomes less effective in promoting chemical reactions, the catalyst's capacity to store and release oxygen generally degrades. The OBD II catalyst monitor diagnostic is based on an correlation between conversion efficiency and oxygen storage capacity. A good catalyst (e.g. 95% hydrocarbon conversion efficiency) shows a relatively flat output voltage on the post-catalyst Heated Oxygen Sensor (HO2S). A degraded catalyst (65% hydrocarbon conversion) shows a greatly increased activity in output voltage from the post catalyst HO2S. The post-catalyst HO2S 2 is used to measure the oxygen storage and release capacity of the catalyst. A high oxygen storage capacity indicates a good catalyst; low oxygen storage capacity indicates a failing catalyst. The TWC and both the Pre and Post Converter HO2S must be at operating temperature in order to achieve correct oxygen sensor voltages like those shown in the Post-Catalyst HO2S 3 Outputs graphic. The catalyst monitor diagnostic is sensitive to the following conditions: Exhaust leaks HO2S Contamination Alternate fuels Exhaust system leaks may cause the following results: Prevent a degraded catalyst from failing the diagnostic Cause a false failure for a normally functioning catalyst Prevent the diagnostic from running Some of the contaminants that may be encountered are phosphorus, lead, silica, and sulfur. The presence of these contaminants prevents the TWC diagnostic from functioning properly. Three-Way Catalyst Oxygen Storage Capacity The control module must monitor the three-way catalyst (TWC) system for efficiency. In order to accomplish this, the control module monitors the pre-catalyst and post-catalyst oxygen sensors. When the TWC is operating properly, the post-catalyst (2) oxygen sensor will have significantly less activity than the pre-catalyst (1) oxygen sensor. The TWC stores the oxygen as needed during the normal reduction and oxidation process. The TWC releases oxygen as needed during the normal reduction and oxidation process. The control module calculates the oxygen storage capacity using the difference between the pre-catalyst and post-catalyst oxygen sensor voltage levels. Whenever the voltage levels of the post-catalyst (2) oxygen sensor nears the voltage levels that of the pre-catalyst (1) oxygen sensor, the efficiency of the catalyst is degraded. Stepped or staged testing levels allow the control module to statistically filter the test information. This prevents falsely passing or falsely failing the oxygen storage capacity test. The calculations performed by the On-Board Diagnostic System are very complex. For this reason, do not use post catalyst oxygen sensor activity in order to determine the oxygen storage capacity unless you are directed to do this by the service information. Three stages are used in order to monitor catalyst efficiency. Failure of the first stage indicates that the catalyst requires further testing in order to determine catalyst efficiency. Failure of the second stage indicates that the catalyst may be degraded. The third stage then looks more closely at the inputs from the pre and post O2S before determining if the catalyst is indeed degraded. This further statistical processing is done in order to increase the accuracy of the oxygen storage capacity type monitoring. Failing the first (stage 0) or the second (stage 1) test DOES NOT indicate a failed catalyst. The catalyst may be marginal or the fuel sulfur content could be very high. Aftermarket HO2S characteristics may be different from the original equipment manufacturer sensor. This may lead to a false pass or a false fail of the catalyst monitor diagnostic. Similarly, if an aftermarket catalyst does not contain the same amount of cerium as the original part, the correlation between oxygen storage and conversion efficiency may be altered enough to set a false DTC. Whenever a cylinder misfires, the misfire diagnostic counts the misfire and notes the crankshaft position at the time it the misfire occurred. These misfire counters are basically a file on each engine cylinder. A current and a history misfire counter is maintained for each cylinder. The misfire current counters (Misfire Cur #1 -8) indicate the number of firing events out of the last 200 cylinder firing events which were misfires. The misfire current counters displays real time data without a misfire DTC stored. The misfire history counters (Misfire Hist #1 - 8) indicate the total number of cylinder firing events which were misfires. The misfire history counters displays 0 until the misfire diagnostic has failed and a DTC P0300 is set. Once the misfire DTC sets, the misfire history counters will be updated every 200 cylinder firing events. The Misfire counters graphic illustrates how these misfire counters are maintained. If the misfire diagnostic reports a failure, the Diagnostic Executive reviews all of the misfire counters before reporting a DTC. This way, the Diagnostic Executive reports the most current information. When crankshaft rotation is erratic, the control module detects a misfire condition. Because of this erratic condition, the data that is collected by the diagnostic can sometimes incorrectly identify which cylinder is misfiring. The Misfire Counters graphic shows there are misfires counted from more than one cylinder. Cylinder #1 has the majority of counted misfires. In this case, the Misfire Counters would identify cylinder #1 as the misfiring cylinder. The misfires in the other counters were just background noise caused by the erratic rotation of the crankshaft. If the number of accumulated is sufficient for the diagnostic to identify a true misfire, the diagnostic will set DTC P0300 - Misfire Detected. Use Techline equipment to monitor misfire counter data on OBD ll compliant vehicles. Knowing which specific cylinders misfired can lead to the root cause, even when dealing with a multiple cylinder misfire. Using the information in the misfire counters, identify which cylinders are misfiring. If the counters indicate cylinders number 1 and 4 misfired, look for a circuit or component common to both cylinders number 1 and 4 such as an open ignition coil in an electronic ignition system. Misfire counter information is located in the Specific Eng. menu, Misfire Data sub-menu of the of the data list. The misfire diagnostic may indicate a fault due to a temporary fault not necessarily caused by a vehicle emission system malfunction. Examples include the following items: Contaminated fuel Running out of fuel Fuel fouled spark plugs Basic engine fault Fuel Trim System Monitor Diagnostic Operation This system monitors the averages of short-term and long-term fuel trim values. If these fuel trim values stay at their limits for a calibrated period of time, a malfunction is indicated. The fuel trim diagnostic compares the averages of short-term fuel trim values and long-term fuel trim values to rich and lean thresholds. If either value is within the thresholds, a pass is recorded. If either value is outside their thresholds, a rich or lean DTC will set. In order to meet OBD ll requirements, the control module uses weighted fuel trim cells in order to determine the need to set a fuel trim DTC. A fuel trim DTC can only be set if fuel trim counts in the weighted fuel trim cells exceed specifications. This means that the vehicle could have a fuel trim problem which is causing a concern under certain conditions (i.e. the engine could be idling high due to a small vacuum leak or rough due to a large vacuum leak) while the engine operates fine at other times. No fuel trim DTC would set (although an engine idle speed DTC or HO2S DTC may set). Remember, use a scan tool in order to observe fuel trim counts while the problem is occurring. Remember, a fuel trim DTC may be triggered by a list of vehicle faults. Make use of all information available (other DTCs stored, rich or lean condition, etc.) when diagnosing a fuel trim fault. Comprehensive Component Monitor Diagnostic The comprehensive component monitoring diagnostics are required to monitor emissions-related input and output powertrain components. The CARB OBD II comprehensive component monitoring list of components Intended to illuminate the malfunction indicator lamp (MIL) is a list of components, features or functions that could fall under this requirement. Input Components The control module monitors the input components for circuit continuity and out-of-range values. This includes performance checking. Performance checking refers to indicating a fault when the signal from a sensor does not seem reasonable, for example, a throttle position (TP) sensor that indicates high TP at low engine loads or MAP voltage. The input components may include but are not limited to the following sensors: The vehicle speed sensor (VSS) The crankshaft position (CKP) sensor The knock sensor (KS) The throttle position (TP) sensor The engine coolant temperature (ECT) sensor The camshaft position (CMP) sensor The manifold absolute pressure (MAP) sensor The mass air flow (MAF) In addition to the circuit continuity and rationality check, the ECT sensor is monitored for the ability to achieve a steady state temperature in order to enable a closed loop fuel control. Output Components The output components respond to control module commands. Components where functional monitoring is not feasible will be monitored for circuit continuity and out-of-range values if applicable. Output components to be monitored include, but are not limited to the following circuits: The idle air control (IAC) motor The control module controlled EVAP canister purge valve The electronic transmission controls The A/C relay The cooling fan relay The VSS output The MIL control The cruise control inhibit California Air Resources Board (CARB) OBD II Comprehensive Component Monitoring List of Components Intended to Illuminate MIL Important Not all vehicles have these components: Transmission range (TR) mode pressure switch Transmission turbine speed sensor (HI/LO) Transmission vehicle speed sensor (HI/LO) Ignition sensor (cam sync, diag) Ignition sensor hi resolution (7x) Knock sensor (KS) Engine coolant temperature (ECT) sensor Intake air temperature (IAT) sensor Throttle position (TP) sensor A, B Manifold absolute pressure (MAP) sensor Mass air flow (MAF) sensor Automatic transmission temperature sensor Transmission torque converter clutch (TCC) control solenoid Transmission TCC enable solenoid Transmission shift solenoid A Transmission shift solenoid B Transmission 3/2 shift solenoid Ignition control (IC) system Idle air control (IAC) coil Evaporative emission purge vacuum switch Evaporative emission canister purge (EVAP canister purge) Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
Logan Posted October 31, 2004 Report Share Posted October 31, 2004 Oh yeah.....are you using GM O2 sensors? I have seen aftermarket O2 sensors not work correctly on GM cars with OBDII. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
druhl Posted October 31, 2004 Author Report Share Posted October 31, 2004 Logan Thanks for the Post it is alot of good information. I put on an aftermarket converter but I bought new GM pre and post oxygen sensors. Have you ever completed the drive cycle and how precise do you have to follow it. I am about 5 minutes from the highway. I am using a autotap scantool on a laptop to monitor the PCM. The system goes to closed loop in just a few minutes and the cat. converter seems to be working fine. I can watch all the oxygen sensors heat up with the autotap scantool with the engine not running and they seem ok. I am not sure what my next move should be. It looks like maybe completing the drive cycle several times. I have been doing the first part of the drive cycle for may days now without success. I warm up with accessories on for 2.5 minutes turn them off and head for the highway and drive 55-60 mph and the systems will not complete . Do you have any suggestions other than that. Maybe replace the other two oxygen sensors but they seem to be working fine. Link to comment Share on other sites More sharing options...
Logan Posted October 31, 2004 Report Share Posted October 31, 2004 Typical OBD II Drive Cycle Diagnostic Time Schedule for I/M Readiness Vehicle Drive Status What is Monitored? Cold Start, coolant temperature less than 50°C (122°F) -- Idle 2.5 minutes in Drive (Auto) Neutral (Man), A/C and rear defogger ON HO2S Heater, Misfire, Secondary Air, Fuel Trim, EVAP Purge A/C off, accelerate to 90 km/h (55 mph), 1/2 throttle. Misfire, Fuel Trim, Purge 3 minutes of Steady State - Cruise at 90 km/h (55 mph) Misfire, EGR, Secondary Air, Fuel Trim, HO2S, EVAP Purge Clutch engaged (Man), no braking, decelerate to 32 km/h (20 mph) EGR, Fuel Trim, EVAP Purge Accelerate to 90-97 km/h (55-60 mph), 3/4 throttle Misfire, Fuel Trim, EVAP Purge 5 minutes of Steady State Cruise at 90-97 km/h (55-60 mph) Catalyst Monitor, Misfire, EGR, Fuel Trim, HO2S, EVAP Purge Decelerate, no breaking. End of Drive Cycle EGR, EVAP Purge Total time of OBD II Drive Cycle 12 minutes That is the drive cycle for the '97. You may have to do it several times. At least you have the laptop so you can see what has passed etc. Dont disconnect the battery or use the 'clear codes' mode. Logan Diagnostic LLC www.airbagcrash.com www.logandieselusa.com www.ledfix.com www.ledfix.com/yukontaillightrepair.html www.ledfix.com/ledreplacements.html www.ledfix.com/j42385toolrental.html Link to comment Share on other sites More sharing options...
druhl Posted November 3, 2004 Author Report Share Posted November 3, 2004 I am still having trouble getting my car to complete the system monitors. I start the car cold idle in drive with a/c and rear defroster on for 2.5 minutes and then head for the highway which is about 5 minutes away. Drive 3 minutes at 55-60 coast to 20 speed back up to 60 mph for 5 minutes and coast back to 20mph. I have done this several times and if I were to quess I would say it is not running the test but I am not sure why. If anyone knows what is going on with this 97 STS please give me a post. The inspection ran out october and I am loosing hope fast. Thanks. Link to comment Share on other sites More sharing options...
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