On Board Diagnostics II PCED

1999 PCED On Board Diagnostics II

SECTION 5: Pinpoint Tests

HF: Catalyst Efficiency Monitor and Exhaust Systems

HF: Introduction

HF1 DTCs P0420 OR P0430: CHECK FOR MISFIRE DETECTION MONITOR DTCS

NOTE 1: Be sure customer has not:

Refueled vehicle with leaded gasoline.
Noticed high vehicle oil consumption.

NOTE 2: If entering this Pinpoint Test for symptoms only, go immediately to HF5 .

NOTE 3: Internal deterioration of a catalytic converter is usually caused by abnormal engine operation upstream of the catalyst. Events that can produce higher than normal temperatures in the catalyst are particularly suspect. For example, misfiring can cause higher than normal catalyst operating temperatures.

Retrieve and record all Continuous Memory DTCs (MIL and non-MIL).

Were any of the following Misfire Detection Monitor DTCs recorded: P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0309 and P0310?

Yes	No
GO to Section 4 , Powertrain Diagnostic Trouble Code (DTC) Charts, to address the Misfire Detection Monitor DTCs.	GO to HF2 .

HF2 CHECK FOR HO2S MONITOR DTCS

NOTE: Incorrect HO2S signal input (such as rich/lean input signal when the engine is operating under lean/rich conditions) can cause an abnormal temperature increase in the catalyst.

Were any of the following HO2S monitor DTCs recorded in HF1: P0136, P0138 and P0141 (Bank 1, rear HO2S) or P0156, P0158 and P0161 (Bank 2, rear HO2S)?

Yes	No
GO to Section 4 , Powertrain Diagnostic Trouble Code (DTC) Charts, to address the HO2S Monitor DTCs.	GO to HF3 .

HF3 CHECK FOR ECT OR CHT SENSOR DTCS

Note: ECT or CHT sensor DTCs can indicate that the thermostat is not operating correctly or that the engine coolant level is not filled to specification, producing above normal operating temperatures.

Were any of the following ECT or CHT sensor DTCs recorded in HF1: P0117, P0118, P0125, P1117, P1285, P1288, P1289, P1290 and P1299?

Yes	No
GO to Section 4 , Powertrain Diagnostic Trouble Code (DTC) Charts, to address the ECT or CHT sensor DTCs.	GO to HF4 .

HF4 CHECK FOR ANY OTHER DTCS

Were any other DTCs recorded in HF1 (not including the initial P0420 or P0430 DTCs)?

Yes	No
GO to Section 4 , Powertrain Diagnostic Trouble Code (DTC) Charts, to address the DTCs.	GO to HF5 .

HF5 CHECK REAR HO2S WIRING AND PCM CONNECTIONS

Note: If the electrical connections of the rear HO2S are interchanged/crossed, the Catalyst Efficiency Monitor Test will fail.

Inspect the wiring of each rear HO2S for proper routing and connection.
Disconnect the PCM, inspect for damaged or pushed out pins, corrosion and loose wires.

Are there any concerns with the HO2S wiring or the PCM connection?

Yes	No
REPAIR any wiring or connection concerns. For PCM pin concerns, REPLACE PCM (refer to Section 2 , Flash EEPROM). COMPLETE Catalyst Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles).	No Electronic EC root causes related to the DTCs or symptoms. GO to HF6 .

HF6 CHECK FUEL PRESSURE

WARNING: THE FUEL SYSTEM WILL REMAIN PRESSURIZED WHEN THE ENGINE IS NOT RUNNING. TO PREVENT INJURY OR FIRE, USE CAUTION WHEN WORKING ON THE FUEL SYSTEM.

Note: Fuel pressures above specification can produce an abnormally rich air/fuel mixture. The rich air/fuel mixture can cause higher than normal catalyst operating temperatures.

If applicable, inspect the vacuum hose going to the fuel pressure regulator for proper installation and cracks. Repair as necessary.
Install fuel pressure gauge.
If applicable, verify vacuum source to fuel pressure regulator.
Start and run the engine at idle. Record the fuel pressure.
Increase engine speed to 2500 rpm and maintain for one minute. Record the fuel pressure.
Key off.

FUEL PRESSURE CHART

Vehicle	kPa	Psi
Contour/Mystique, Cougar (2.5L)	310-415	45-60
Continental	310-415	45-60
Escort/Tracer, Mustang, LS6/LS8	240-380	35-55
Ranger	386-496	56-72
Ranger (Flex Fuel)	380-517	55-75
All Others	207-310	30-45

Was the fuel pressure within specifications listed in the chart above?

Yes	No
Fuel pressure is OK. REMOVE the fuel pressure gauge. GO to HF7 .	Fuel pressure is out of specification. GO to Pinpoint Test HC1 Fuel Delivery Systems, for diagnosis.

HF7 CHECK FOR OBVIOUS LEAK SOURCES IN THE EXHAUST SYSTEM

Note: If a catalyst is in series with a leaking exhaust system, it can fail the Catalyst Efficiency Monitor test.

Inspect the following for leaks, cracks, loose connections or punctures:

Exhaust manifold.
Front exhaust pipe.
Rear exhaust pipe.
Muffler/tailpipe assembly.

Are the above components free of cracks and punctures,etc.?

Yes	No
GO to HF8 .	REPAIR the leak source(s). COMPLETE Catalyst Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles).

HF8 CHECK FOR OBVIOUS RESTRICTIONS IN THE EXHAUST SYSTEM

Inspect the following for dents, areas of collapsed material and unusual bending:

Front exhaust pipe.
Rear exhaust pipe.
Muffler/tailpipe assembly.

Are the components free of dents and areas of collapsed material or unusual bending, etc.?

Yes	No
GO to HF9 .	REPAIR the restricted component(s) as necessary. COMPLETE Catalyst Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles).

HF9 CHECK MANIFOLD VACUUM FOR INDICATION OF EXCESSIVE EXHAUST SYSTEM RESTRICTION

Attach a vacuum gauge to the intake manifold vacuum source.
Monitor RPM with scan tool or tachometer.
Observe the vacuum gauge needle while completing the following:

Note: The vacuum gauge reading may be normal when the engine is first started and idled. However, excessive restriction in the exhaust system will cause the vacuum gauge needle to drop to a low point even while the engine is idled.

Start the engine and gradually increase the engine speed to 2000 rpm with the transmission in NEUTRAL.

Decrease engine speed to base idle rpm.
Key off.

Did manifold vacuum rise above 54 kPa (16 inches-Hg) with the engine speed at 2000 rpm?

Yes	No
GO to HF10 .	Manifold vacuum did not reach an acceptable level. GO to HF11 to check for excessive restriction in the exhaust system.

HF10 CHECK MANIFOLD VACUUM FOR INDICATION OF MODERATE EXHAUST SYSTEM RESTRICTION

Key on, engine idling.
Increase the engine speed gradually from base idle rpm to 2000 rpm with the transmission in NEUTRAL.
Observe the speed the vacuum gauge needle rises, while maintaining the increased engine rpm.
NOTE 1: On a non-restricted exhaust system, the vacuum gauge needle will rise quickly to the normal range as the increased rpm is maintained.
NOTE 2: On a restricted exhaust system, the vacuum gauge needle will rise slowly to the normal range as the increased rpm is maintained.
NOTE 3: The rate of speed the vacuum gauge needle rises to the normal range is slower on a restricted system than on a non-restricted system as the increased rpm is maintained.
Decrease engine speed to base idle rpm.
Key off.

Is the rate of speed that the vacuum gauge needle rises back to the normal range (above 54 kPa (16 inches-Hg)) much slower than that of a non-restricted system?

Yes	No
A moderate restriction may be present. GO to HF11 .	No indications of restrictions or leaks have been detected in the exhaust system. If here because of DTCs P0420 or P0430, the catalytic converter is chemically inactive. REPLACE the catalytic converter. COMPLETE Catalyst Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles). For further diagnosis of symptom (e.g. Lack of Power, Loss of Power, or No Start) REFER to Section 3 , Symptom Charts.

Yes

A moderate restriction may be present. GO to HF11 .

No indications of restrictions or leaks have been detected in the exhaust system. If here because of DTCs P0420 or P0430, the catalytic converter is chemically inactive. REPLACE the catalytic converter. COMPLETE Catalyst Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles). For further diagnosis of symptom (e.g. Lack of Power, Loss of Power, or No Start) REFER to Section 3 , Symptom Charts.

HF11 CHECK MANIFOLD VACUUM WITH EXHAUST MANIFOLD DISCONNECTED FOR INDICATION OF A RESTRICTION

Note: An intake manifold gasket leak can also cause the vacuum gauge needle to remain well below the normal range.

Disconnect exhaust system immediately after the exhaust manifold.
Repeat the vacuum measurement found in test step HF10 .

Did the vacuum needle QUICKLY rise above 54 kPa (16 inches-Hg) with the engine speed at 2000 rpm?

Yes	No
The exhaust system restriction is downstream of the exhaust manifold. RECONNECT exhaust system at exhaust manifold. GO to HF12 .	A restriction is present in the exhaust manifold. INSPECT each exhaust port for casting flash/restrictions by dropping a length of chain into it (NOTE: Do not use a wire or lamp to check the ports. The restriction can be small enough for both to pass through, but large enough to cause excessive back-pressure at high engine rpm.). REPLACE the exhaust manifold if unable to remove the casting flash/restriction. COMPLETE Catalyst Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles).

Yes

The exhaust system restriction is downstream of the exhaust manifold. RECONNECT exhaust system at exhaust manifold. GO to HF12 .

A restriction is present in the exhaust manifold. INSPECT each exhaust port for casting flash/restrictions by dropping a length of chain into it (NOTE: Do not use a wire or lamp to check the ports. The restriction can be small enough for both to pass through, but large enough to cause excessive back-pressure at high engine rpm.). REPLACE the exhaust manifold if unable to remove the casting flash/restriction. COMPLETE Catalyst Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles).

HF12 CHECK MANIFOLD VACUUM WITH MUFFLER/TAILPIPE ASSEMBLY DISCONNECTED FOR INDICATION OF A RESTRICTION

Disconnect muffler/tailpipe assembly from the catalytic converter.
Repeat the vacuum measurement found in test step HF10 .

Did the vacuum needle QUICKLY rise above 54 kPa (16 inches-Hg) with the engine speed at 2000 rpm?

Yes	No
There is a restriction in the muffler/tailpipe assembly. REPLACE the muffler/tailpipe assembly. COMPLETE Catalyst Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles).	There is a restriction in the catalytic converter. REPLACE the catalytic converter. INSPECT the muffler to be certain converter debris has not entered. COMPLETE Catalyst Monitor Repair Verification Drive Cycle (Refer to Section 2 , Drive Cycles).