Diagnostic Trouble Codes with Test Charts (V8): Overview BMW X5 E53 рестайлинг

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ENGINE PERFORMANCE & TRANSMISSION DIAGNOSTIC TROUBLE CODES TABLE

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TEST GROUP IDENTIFICATION

BMW supplies test group information in the following categories

1. «CATALYST MONITORING»(ref-247741-S20146029602007020700000)
2. «MISFIRE MONITORING»(ref-247741-S14233668552007020700000)
3. «EVAPORATIVE SYSTEM MONITORING»(ref-247741-S14233668552007020700000)
4. «SECONDARY AIR SYSTEM MONITORING»(ref-247741-S10311028272007020700000)
5. «FUEL SYSTEM MONITORING»(ref-247741-S18612322232007020700000)
6. «OXYGEN SENSOR MONITORING»(ref-247741-S33703421492007020700000)

General Description

The Catalyst Monitor is based on determining the oxygen storage capacity. The nonlinear correlation between conversion efficiency and storage capacity has been shown in various investigations. The catalyst is diagnosed by comparing its storage capacity against the storage capacity of a borderline catalyst.

The oxygen storage capacity can be determined by one of the following two methods

1. Oxygen reduction after fuel cut-off (passive test) During fuel cut-off oxygen is stored in the catalyst. After fuel cut the catalyst is operated with a rich A/F ratio and the amount of removed oxygen is determined. If this passive test indicates an oxygen storage capacity significantly above the borderline catalyst, the catalyst is determined to be good; otherwise the monitor will be restarted after the next fuel cut-off.
2. Oxygen filling (active test)

1. First, the engine is operated with a low A/F ratio to remove any oxygen from the catalyst.
2. Then, the engine is operated with a high A/F ratio. The O xygen S torage C apacity (OSC) is calculated out of the oxygen mass stored in the catalyst as follows: OSC = air mass flow * lean mixture (-1) * dt
3. The engine is operated in this mode until the oxygen stored in the catalyst exceeds a calibrated limit or the downstream oxygen sensor indicates the catalyst is completely saturated with oxygen.
4. The catalyst is then diagnosed by comparing its oxygen storage capacity to the calibrated threshold of a borderline catalyst.

System overview

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The method of engine misfire detection is based monitoring the crankshaft acceleration. The engine roughness is derived from the differences in the segment period durations that are corrected and compared to engine speed - and load-dependent thresholds.

This method consists of the following main parts

1. data acquisition and adaptation of sensor wheel
2. calculation of engine roughness
3. comparison with a threshold depending on operating points
4. monitoring for extreme road and operating conditions, during which misfire detection should be disabled for a short time to avoid false indications
5. statistics and fault processing

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General Description Of Leak Measurement

The evaporative system monitoring permits the detection of leaks having a diameter of 0.5 mm and up.

By means of a D iagnostic M odule- T ank L eakage (DM-TL), an electrically actuated pump located at the atmospheric connection of the evaporative canister, a pressure test of the evaporative system is performed in the following order

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1. During the Reference Leak Measurement, the electrical actuated pump delivers through the reference restriction. The engine-management system measures the pump's electrical current consumption in this phase.
2. During the Leak Measurement, the electrically actuated pump delivers air through the charcoal canister into the fuel tank system. The pressure in the evaporative system may be up to 25 hPa depending on the fuel level in the tank. The engine management system measures the pump's electrical current consumption. A comparison of the currents of the reference leak measurement and the leak measurement is an indication of the tightness of the tank system.
3. After the test the remaining pressure in the evaporative system is bled off through the charcoal canister by switching off the pump and solenoid valve.

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General Description Of Secondary Air System Monitoring

After a cold start the secondary air pump starts and the secondary air valve opens. Air is forced into the exhaust ports of the engine and mixes with the engine exhaust gases. This results in a lean mixture at the upstream oxygen sensor.

The front oxygen sensors will measure the exhaust lambda and therefore calculate the secondary airflow rate.

The measured secondary airflow rate is compared with the secondary airflow rate model and the quotient is obtained and used as the relative secondary air volume. This volume is compared with the secondary air flow threshold.

After the secondary air phase, the fuel control system begins closed-loop operation. During this phase, the quality of the open-loop A/F ratio is checked to assure the accuracy of the diagnostic.

When the lambda control is between pre-set limits and the secondary airflow rate is measured to be too low, a failure of the secondary air system is diagnosed.

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Abbreviations For Fuel Delivery System

QU1 upper air flow threshold range 1

NU1 upper engine speed threshold range 1

TLARN upper engine load threshold f(n) range 2

TLL2 lower engine load threshold range2

tra additive per time unit learning correction coefficient (range 1)

TRADN lower diagnosis threshold of tra

TRADX upper diagnosis threshold of tra

fra multiplicative learning correction coefficient (range 2)

FRADN lower diagnosis threshold of fra

FRADX lower diagnosis threshold of fra

QL2 lower air flow threshold range 2

The Wide Range Air Fuel Ratio Sensor is ready for operation at temperatures above 600°C. In most cases heat from the exhaust gas is not sufficient for to achieve that temperature, and so the sensor heating is needed for proper functioning of the sensor.

The diagnosis consists of three checks

Operational Readiness

Sensor readiness depends on heater performance. For this reason, the time delay between "heater on" and "operational readiness" is monitored. Therefore sensor readiness is checked at a specified time after the heater has been switched on. If the sensor is not ready, a fault code is set.

Heater Performance In Fuel Cut-Off Operation

A second check is performed during fuel cut-off. During this mode the sensor output voltage is expected to remain within a specified range. Otherwise, the heater performance is not sufficient and a fault code is set.

(Scheme 319) shows the output voltage characteristic of the Wide Range Air Fuel Sensor (WRAF).

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The diagnosis of the upstream oxygen sensor consists of four checks as follows

The heater of downstream narrow-band type 02 sensor consists of two checks

This diagnostic function detects all electrical connection faults of the downstream heated oxygen sensor, except for heater faults.

An open circuit or a damaged sensor heater is detected when the sensor voltage remains within a certain voltage range for a period of time.

A short circuit of the sensor signal wire to battery voltage is detected when the voltage of the evaluation circuit is exceeds a specified value for a period of time.

A wire-to-wire short circuit between sensor signal and ground lead is detected when the evaluation voltage remains under a calibration threshold for a period of time, while the oxygen sensor is cold after engine start.

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Activity check in normal operation

This function checks whether the sensor output voltage of the downstream sensor (Nerst type) remains permanently above or below a specified threshold.

If the rear closed loop control is active, the oxygen sensor voltage must cross a threshold at least once within a specified period of time.

Signal performance in fuel cut-off operation

This function checks whether the output voltage reaches a value below a specified lean threshold during a defined period of fuel cut-off and reasonable exhaust gas temperature. A fault is set if the signal remains above the threshold.