HU: Intake Air Systems

HU: Introduction See: HU: Intake Air Systems - Introduction

HU1 CHECK FOR INCORRECT IDLE SPEED

Note: Vehicle must be at operating temperature and at idle for a minimum of one minute. If here for a part throttle symptom, GO to HU4.

• Key on, engine running.
• Determine if idle speed is incorrect. Refer to the Typical Reference Value Charts in Section 6 See: SECTION 6: Reference Values , if necessary.
• Read the vehicle tachometer (if equipped) or connect the scan tool to the data link connector (DLC) and view the rpm PID.

Is vehicle idle speed incorrect?
Yes

• For a high idle concern, be sure throttle arm contacts return stop, then GO to HU6

0. For other idle speed concerns, GO to HU7 .

No

• KEY OFF. GO to HU2

.

HU2 CHECK FOR STICKING/BINDING CONDITION

• Gently cycle throttle from fully closed to fully open and back to fully closed. Check for binding/sticking in travel.

Is a stick or bind condition present?
Yes

• GO to HU3

.

No

• GO to HU4

.

HU3 ISOLATE BINDING/STICKING CONCERN

• Disconnect accelerator cable and speed control cable from throttle body linkage.

• Rotate throttle body linkage.

Does the throttle body rotate freely without a sticking, binding or grabbing condition?
Yes

• REPAIR cable(s) causing the concern.

No

• REPLACE throttle body assembly.

HU4 CHECK FUNCTIONALITY OF THE THROTTLE POSITION SENSOR

• Key on.
• View TP V PID with the scan tool.
• From closed throttle, slowly begin to press accelerator to wide open throttle.

Did the TP V PID display a smooth reading during accelerator movement?
Yes

• KEY OFF. GO to HU5

.

No

• REPLACE throttle position sensor.

HU5 CHECK FOR AIR CLEANER ELEMENT AND INLET FOR RESTRICTIONS

• Remove air cleaner element. Check for a plugged or dirty element.
• Check for any restrictions along the air inlet path from the air inlet back to the throttle body.

Are any restrictions present?
Yes

• REPLACE air cleaner element or clear any restrictions.

No

• REINSERT original air cleaner element. GO to HU6

.

HU6 CHECK FOR A POSITIVE CRANK VENTILATION CONCERN

Note: A high idle may indicate incorrect PCV valve size or vacuum leak.

• Inspect PCV valve connections for leaks or cracks.
• Remove PCV valve and inspect for plugging or an incorrect valve.

Is a PCV concern present?
Yes

• REPLACE PCV valve or REPAIR leak or crack.

No

• For high idle, GO to HU9

, otherwise, RECONNECT PCV valve. GO to HU7
.

HU7 CHECK FOR IDLE AIR CONTROL VALVE RESPONSE

• Key on, engine running.
• With vehicle at operating temperature and at idle for a minimum of one minute, disconnect the IAC valve harness connector.

Did engine idle speed drop or nearly stall?
Yes

• GO to HU8

.

No

• For a high idle with no idle speed drop when disconnecting IAC, GO to HU9

.

• For a low idle with no idle speed drop when disconnecting IAC, REPLACE the IAC valve.

HU8 INSPECT THROTTLE BODY PLATE HOLE FOR PLUGGING

Note: Only some applications have a throttle plate hole. If not equipped, return to symptom charts. See: Symptom Related Diagnostic Procedures

• Detach resonator from throttle body assembly.
• Inspect throttle plate hole for any restrictions.

Is the throttle plate hole restricted?
Yes

• CLEAR throttle plate hole.

No

• Return to Symptom Charts. See: Symptom Related Diagnostic Procedures

HU9 CHECK FOR VACUUM LEAKS

• Listen for vacuum leaks.
• Inspect entire air intake system from the mass air flow (MAF) sensor to the intake manifold for leaks such as:
• cracked or punctured inlet air tube.
• loose connections on the inlet air tube at the air cleaner housing or throttle body.
• idle air control (IAC) valve assembly or gasket seal.
• EGR valve gasket seal leak to intake manifold.
• intake manifold assembly or gasket seal.
• EGR valve diaphragm or control solenoid.
• vacuum supply connectors and hose.

Are any leaks detected?
Yes

• KEY OFF. REPAIR any leaks.

No

• REPLACE IAC valve if idle speed does not drop when disconnecting harness connector otherwise, KEY OFF. GO to HU10

.

HU10 CHECK THROTTLE BODY FOR EXCESSIVE WEAR

• Remove throttle body assembly (refer to Fuel Delivery and Air Induction).
• Hold throttle body up to a light source.
• Rotate the throttle lever to wide open throttle and inspect bore for excessive wear or grooving.
• Rotate the throttle lever to closed throttle position while inspecting for misaligned or worn plate. Look for excessive gap between bore and plate area.

Is a concern detected?
Yes

• REPLACE throttle body.

No

• RETURN to Symptom Charts. See: Symptom Related Diagnostic Procedures

HU15 DTCS P1516, P1517, P1518, P1519, P1520, P1537, P1538 VISUAL INSPECTION

Note: Refer to the PCM connector pin numbers in the beginning of the pinpoint test.

• View linkage or cable routing. Check for any binding or improper routing. Cable core wire (if applicable) at IMRC/IMSC housing attachment must have slack and lever must contact close plate stop screw. For Focus/Escort and 2.3L Ranger, a visual inspection may not be appropriate. GO to HU17. Refer to the IMRC/IMSC system description in Section 1 See: SECTION 1: Description and Operation , Intake Air and Throttle Body, for illustrations.

Note: The IMRC/IMSC return springs are strong. Make sure the return springs operate properly and plates open and close fully. On vacuum operated systems engine must run for 20 seconds then return to KOEO for testing.

• Manually open and close IMRC/IMSC plates at intake manifold and feel for sticking/binding.

Is concern indicated?
Yes

• GO to HU16

.

No

• GO to HU17

.

HU16 PERFORM IMRC/IMSC PHYSICAL TEST

• Disconnect IMRC/IMSC linkage or cables(s) from runner(s) or remove actuator assembly for Focus/Escort.

Note: IMRC/IMSC return springs are strong.

• Rotate IMRC/IMSC lever(s) fully open to fully closed without obstruction and contacting closed stop screw.
• Feel for sticking or binding during rotation and spring tension of approximately.34 to.45 Nm (3 to 4 lb-in).

Is concern indicated?
Yes

• CLEAN or REPAIR runners. REFER to Engine. GO to HU38

.

No

• REPLACE IMRC/IMSC actuator. GO to HU38

.

HU17 PERFORM IMRC/IMSC FUNCTIONAL TEST

• Connect scan tool to data link connector (DLC).
• Key on, engine off.

Note: All except Focus and 2.3L Ranger, if the IMRC/IMSC plates open immediately when the key is turned on with engine off, GO to HU23.

For Focus and 2.3L Ranger, monitor IMRCM/SCVM PID or voltage. GO to HU23 if PID displays less than 1 volt.

• Access Output Test Mode (OTM) (refer to Section 2 See: SECTION 2: Diagnostic Methods ).

WARNING: KEEP FINGERS CLEAR OF IMRC/IMSC LEVER/CABLE MECHANISM.

• Turn all outputs on.
• When IMRC/IMSC is commanded on, lever(s) should rotate to full-open position. At least one of the levers should contact the wide open stop, the other may be slightly off the wide open stop. For Focus/Escort and 2.3L Ranger, listen for IMRC/IMSC to actuate.

Did the IMRC/IMSC lever(s) cycle from fully closed and remain fully open while all outputs were on?
Yes

• GO to HU25

.

No

• GO to HU18

.

HU18 CHECK IMRC/IMSC ACTUATOR VPWR CIRCUIT FOR AN OPEN IN HARNESS

• Disconnect IMRC/IMSC actuator harness connector.
• Measure VPWR circuit voltage at the IMRC/IMSC actuator harness connector.

Is IMRC/IMSC VPWR voltage greater than 10.5 volts?
Yes

• GO to HU19

0. For Focus/Escort, GO to HU20 .

No

• KEY OFF. REPAIR open circuit. GO to HU38

.

HU19 CHECK IMRC/IMSC GROUND CIRCUIT FOR OPEN IN HARNESS

• Measure voltage between ground and VPWR circuits at the IMRC/IMSC actuator harness connector.

Is voltage greater than 10.5 volts?
Yes

• GO to HU20

.

No

• REPAIR open circuit. GO to HU38

.

HU20 VERIFY DRIVER CIRCUIT FUNCTION

• Access Output Test Mode (OTM) (refer to Section 2 See: SECTION 2: Diagnostic Methods ).
• Place a test lamp between VPWR and the IMRC/IMSC signal circuit at the IMRC/IMSC actuator harness connector.
• Turn all outputs on.

Did the test lamp cycle from off to on?
Yes

• KEY OFF. GO to HU32

.

No

• KEY OFF. GO to HU21

.

HU21 CHECK IMRC/IMSC DRIVER CIRCUIT FOR OPEN IN HARNESS

• Disconnect PCM.
• Measure resistance of IMRC/IMSC signal circuit between PCM harness connector and the IMRC/IMSC actuator harness connector.

Is resistance less than 5 ohms?
Yes

• GO to HU22

.

No

• REPAIR open circuit. GO to HU38

.

HU22 CHECK IMRC/IMSC DRIVER CIRCUIT FOR SHORT TO VPWR IN HARNESS

• Key on, engine off.
• Measure voltage between IMRC/IMSC signal circuit at the IMRC/IMSC actuator harness connector and ground.

Is voltage less than 10.5 volts?
Yes

• Possible intermittent concern. GO to Z1 See: Z: Intermittent - Pinpoint Test

0. REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM) after determining concern is not intermittent. GO to HU38 .

No

• REPAIR short circuit. GO to HU38

.

HU23 CHECK IMRC/IMSC DRIVER CIRCUIT FOR SHORT TO GROUND OR SHORT TO MONITOR CIRCUIT WITH PCM CONNECTED

• Key off.
• Measure resistance between the IMRC/IMSC driver circuit to PWR GND and then to SIG RTN and then to the monitor circuit at the IMRC/IMSC harness connector.

Are all resistances greater than 10,000 ohms?
Yes

• REPLACE IMRC/IMSC. GO to HU38

.

No

• GO to HU24

.

HU24 CHECK IMRC/IMSC DRIVER CIRCUIT FOR SHORT TO GROUND OR SHORT TO MONITOR CIRCUIT WITH PCM DISCONNECTED

• Disconnect PCM harness connector.
• Measure the resistance between the IMRC/IMSC driver circuit to PWR GND and then to SIG RTN and then to the monitor circuit at the IMRC/IMSC harness connector.

Are all resistances greater than 10,000 ohms?
Yes

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). GO to HU38

.

No

• REPAIR the appropriate circuit for short. GO to HU38

.

HU25 VIEW IMRC/IMSC MONITOR PID TO DETERMINE PATH FOR POSSIBLE SHORT

Note: All vehicles will display VREF for IMRCM/SCVM PID except 3.8L and 4.2L which will display approximately 2.5 volts.

• With the scan tool, monitor the IMRCM/SCVM PID or voltage.

Is the IMRCM/SCVM PID displaying either VREF or approximately 2.5 volts?
Yes

• GO to HU26

.

No

• GO to HU30

.

HU26 CHECK IMRC/IMSC MONITOR PID TO DETERMINE A SHORT TO VPWR

• With the scan tool, monitor the IMRC/IMSCM PID or voltage while in Output Test Mode.
• Turn all output on.

Is the IMRC/IMSCM PID displaying less than 1 volt with all outputs on?
Yes

• GO to HU27

.

No

• GO to HU32

.

HU27 CHECK IMRC/IMSC MONITOR CIRCUIT FOR SHORT TO VPWR AT IMRC/IMSC HARNESS CONNECTOR

• Disconnect IMRC/IMSC actuator harness connector.
• Key on, engine off.
• Measure voltage between monitor circuit at the IMRC/IMSC actuator harness connector and ground.

Is voltage greater than 10.5 volts?
Yes

• KEY OFF. GO to HU28

.

No

• KEY OFF. GO to HU29

.

HU28 DETERMINE SHORT TO POWER WITH PCM DISCONNECTED

• Key on, engine off.
• Disconnect PCM.
• Measure voltage between monitor circuit at the IMRC/SCVM harness connector and ground.

Is voltage greater than 10.5 volts?
Yes

• KEY OFF. REPAIR short circuit. GO to HU38

.

No

• KEY OFF. REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). GO to HU38

.

HU29 CHECK MONITOR FOR SHORT TO VPWR AT IMRC/IMSC ACTUATOR

• Measure actuator resistance between the monitor circuit and VPWR.

Is resistance greater than 10,000 ohms?
Yes

• Possible intermittent concern. GO to Z1 See: Z: Intermittent - Pinpoint Test

0. REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM) after determining fault is not intermittent.GO to HU38 .

No

• REPLACE IMRC/IMSC actuator. GO to HU38

.

HU30 DETERMINE IMRC/IMSC MONITOR CIRCUIT SHORT TO GROUND

• With the scan tool, monitor the IMRCM/SCVM PID or voltage.
• While viewing PID, disconnect the IMRC/SCVM harness connector.

Did voltage change from less than 1 volt to VREF when disconnecting the IMRC/SCVM harness connector?
Yes

• KEY OFF. REPLACE IMRC/IMSC actuator. GO to HU38

.

No

• KEY OFF. GO to HU31

.

HU31 CHECK IMRC/IMSC MONITOR HARNESS FOR SHORT TO GROUND

• Disconnect PCM.
• Measure resistance between IMRC/IMSC monitor and ground (if applicable) and SIG RTN pins at the IMRC actuator harness or SCVM harness connector.

Is resistance greater than 10,000 ohms?
Yes

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). GO to HU38

.

No

• REPAIR short circuit. GO to HU38

.

HU32 CHECK MONITOR CIRCUIT RESPONSE

• Disconnect IMRC actuator or SCVM harness connector.
• With the scan tool, monitor the IMRCM/SCVM PID or voltage.
• Connect a jumper lead from the IMRC/IMSC monitor pin to ground at the harness connector.

Did the IMRCM/SCVM PID voltage cycle from VREF to less than 1 volt when inserting the jumper?
Yes

• KEY OFF. GO to HU33

.

No

• KEY OFF. GO to HU36

.

HU33 CHECK SIG RTN OR CHASSIS GROUND CIRCUIT CONTINUITY WITH PCM CONNECTED

• Measure resistance of SIG RTN or chassis ground circuit between IMRC/IMSC actuator harness or SCVM harness connector and B-.

Is resistance less than 5 ohms?
Yes

• GO to HU34

.

No

• GO to HU35

.

HU34 CHECK MONITOR LINE FOR INTERMITTENT OPEN

• Measure resistance of monitor line while wiggling and bending harness from IMRC/SCVM harness connector to PCM harness connector.

Is the resistance fluctuating while checking the harness?
Yes

• REPAIR intermittent open circuit. GO to HU38

.

No

• REPLACE IMRC actuator or IMSC actuator. GO to HU38

.

HU35 CHECK SIG RTN OR CHASSIS GROUND CIRCUIT CONTINUITY WITH PCM DISCONNECTED

• Disconnect PCM from harness connector.
• Measure resistance of SIG RTN or chassis ground circuit between PCM harness connector and IMRC/IMSC actuator harness connector.

Is resistance less than 5 ohms?
Yes

• Possible intermittent concern. GO to Z1 See: Z: Intermittent - Pinpoint Test

0. REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM) after determining concern is not intermittent. GO to HU38 .

No

• REPAIR open circuit. GO to HU38

.

HU36 CHECK MONITOR LINE CONTINUITY

• Disconnect PCM from harness connector.
• Measure resistance of IMRC/IMSC monitor circuit between PCM harness connector and IMRC actuator or SCVM harness connector.

Is resistance less than 5 ohms?
Yes

• GO to HU37

.

No

• REPAIR open circuit. GO to HU38

.

HU37 CHECK MONITOR CIRCUIT FOR INTERMITTENT OPEN

• Measure resistance of monitor line while wiggling and bending harness from IMRC/SCVM harness connector to PCM harness connector.

Is the resistance fluctuating while checking the harness?
Yes

• REPAIR intermittent open. GO to HU38

.

No

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). GO to HU38

.

HU38 IMRC/IMSC REPAIR VERIFICATION DRIVE CYCLE

• Key on, engine off.
• Connect scan tool to data link connector (DLC)
• CLEAR the DTCs.
• Access IMRC/IMSC and IMRCM/SCVM PIDs or voltage.
• Drive vehicle, obeying all traffic and safety laws.
• Safely perform three accelerations from stop to more than 3500 rpm.
• Watch for PIDs or voltage to change.
• Perform Quick Test (refer to Section 4, Powertrain Diagnostic Trouble Code (DTC) Charts See: A L L Diagnostic Trouble Codes ( DTC )\Testing and Inspection\Diagnostic Trouble Code Descriptions).

Are any DTCs received?
Yes

• GO to Section 4, Powertrain Diagnostic Trouble Code (DTC) Charts See: A L L Diagnostic Trouble Codes ( DTC )\Testing and Inspection\Diagnostic Trouble Code Descriptions.

No

• PASSED IMRC/IMSC Drive cycle. No IMRC/IMSC concern is present at this time.

HU65 DTC P1549: PERFORM VISUAL INSPECTION

Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

• Inspect IMT Valve System. Check to be sure the harness is intact and the connector is firmly in place.

Is fault indicated?
Yes

• REPAIR as necessary. REFER to Engine for component removal procedure. VERIFY a symptom no longer exists.

No

• Passed visual inspection. GO to HU66

.

HU66 CHECK PCM DRIVER COMMAND

Note: Vehicle must be driven if rev limiter does not allow 3500 rpm in the bay.

• Connect scan tool to data link connector (DLC).
• Key on, engine running.
• Access IMTV PID.
• Increase engine speed slowly to about 4000 rpm while observing IMTV PID.

Does PID read 100% then drop to 50% while rpm was above 3500?
Yes

• KEY OFF. Passed test. GO to HU67

.

No

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). VERIFY a symptom no longer exists.

HU67 CHECK IMT VALVE ACTUATOR VPWR CIRCUIT FOR OPEN IN HARNESS

• Disconnect harness connector from the actuator.
• Key on, engine off.
• Measure VPWR circuit voltage at the harness connector.

Was the voltage greater than 10.5 volts?
Yes

• KEY OFF. Passed check. GO to HU69

.

No

• REPAIR IMT valve actuator VPWR circuit for open. VERIFY a symptom no longer exists.

HU69 CHECK FOR OPEN SIGNAL CIRCUIT BETWEEN PCM AND IMT VALVE ACTUATOR

• Disconnect PCM.
• Measure resistance of Circuit between PCM test pin 46 and actuator harness connector.

Is the resistance less than 5.0 ohms?
Yes

• Passed test. GO to HU70

.

No

• REPAIR IMT Valve Actuator Signal Circuit open. VERIFY a symptom no longer exists.

HU70 CHECK IMT VALVE ACTUATOR FOR SHORT TO PWR GND

• Measure resistance between PCM test pin 46 and test pin 77 or 103.

Is resistance greater than 10,000 ohms?
Yes

• Passed check. GO to HU71

.

No

• REPAIR IMT Valve actuator signal circuit for short to PWR GND. VERIFY a symptom no longer exists.

HU71 CHECK IMT VALVE ACTUATOR SIGNAL CIRCUIT FOR SHORT TO VPWR

• Key on, engine off.
• Measure voltage between PCM test pin 46 and 77 or 103.

Is the voltage less than 1 volt?
Yes

• KEY OFF. Passed check. GO to HU72

.

No

• REPAIR IMT Valve actuator signal circuit for short to VPWR. VERIFY a symptom no longer exists.

HU72 CHECK PCM DRIVER FOR IMT VALVE ACTUATOR

• Reconnect PCM.
• Connect test lamp to VPWR and signal at the harness connector.
• Connect scan tool to data link connector (DLC).
• Key on, engine off.
• Access Output Test Mode (OTM) (Refer to scan tool instruction manual).
• Command all outputs on.

Was the test lamp off before commanding all outputs on and on with all outputs on?
Yes

• KEY OFF. Passed test. GO to HU73

.

No

• REPLACE PCM (refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM) See: Programming and Relearning\Flash Electrically Eraseable Programmable Read Only Memory - Flash EEPROM). VERIFY a symptom no longer exists.

HU73 CHECK IMT VALVE SHUTTER FOR DAMAGE

• Remove IMT Valve (Refer to Computers and Control Systems).
• Visually inspect IMT valve shutter for damage.
• Rotate shutter by hand.

Does the shutter bind or appear damaged?
Yes

• Damaged shutter. REPLACE IMT valve. VERIFY a symptom no longer exists.

No

• Passed test. Leave IMT Valve disassembled. GO to HU74

.

HU74 CHECK IMT VALVE ACTUATOR FOR COIL DAMAGE

• Reconnect IMT valve harness connector.
• Key on, engine off.
• Access Output Test Mode (OTM) (Refer to scan tool instruction manual).
• Command all outputs on.

Did the IMT valve shutter rotate when commanding all outputs on?
Yes

• Passed check. Fault is intermittent. GO to Z1 See: Z: Intermittent - Pinpoint Test

.

No

• REPLACE IMT valve actuator. VERIFY a symptom no longer exists.