Mechanics

MERCURY COUGAR ENGINE PROBLEM

1997 Mercury Cougar • 95,000 miles

Codes p1443 and po174 are still coming up I replaced canister purge solenoid
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December 7, 2012.




HW: Evaporative Emission (EVAP) - Purge Flow System

NOTE: Ford DOES NOT provide a procedure to perform the following Pinpoint Test without the Rotunda Evaporative Emission System Tester 134-00056 or equivalent.

HW1 - DTC P0443- Check VPWR Voltage To EVAP Canister Purge Valve

Diagnostic Trouble Code (DTC) P0443 indicates a failure in the EVAP canister purge valve circuit. Possible causes: VPWR circuit open
EVAP CANISTER PURGE open
EVAP CANISTER PURGE shorted to PWR GND or SIG RTN
Damaged EVAP canister purge valve
Damaged PCM
Key off.
Disconnect EVAP canister purge valve.
Key on, engine off.
Measure VPWR circuit voltage at EVAP canister purge valve harness connector.
Key off.

Was voltage greater than 10.5V?

YES GO to HW2.
NO REPAIR open circuit. RESTORE vehicle. COMPLETE PCM reset to clear DTCs. RERUN Quick Test.

HW2 - Check EVAP Canister Purge Valve Resistance

Measure EVAP canister purge valve resistance.

Is resistance between 30 and 90 ohms (or 30 and 38 ohms for Continental, E-Series, and F-Series)?

YES For Escort/Tracer, Mustang, Thunderbird/Cougar, Ranger, and Aerostar: GO to HW3.
All others: GO to HW4.
NO REPLACE damaged EVAP canister purge valve. RESTORE vehicle. GO to HW42. See: HW41 - HW43

HW3 - Check EVAP Canister Purge Valve and VPWR Circuits For Short To Valve Case Ground

Measure resistance between EVAP CANISTER PURGE pin and valve casing at EVAP canister purge valve.
Measure resistance between VPWR pin and valve casing at EVAP canister purge valve.

Are both resistances greater than 90 ohms?

YES GO to HW4.
NO REPLACE damaged EVAP canister purge valve. RESTORE vehicle. GO to HW42. See: HW41 - HW43

HW4 - Check EVAP Canister Purge Circuit For Open In Harness

Install breakout box, leave PCM disconnected.
Measure resistance between PCM test pin 67 or PCM test pin 56 and EVAP canister purge circuit at the EVAP canister purge valve harness connector.

Is the resistance less than 5 ohms?

YES GO to HW5.
NO REPAIR open circuit. RESTORE vehicle. COMPLETE PCM reset to clear DTCs. RERUN Quick Test.

HW5 - Check EVAP Canister Purge Circuit For Short To PWR GND In Harness

Disconnect tool from DLC.
Measure resistance between PCM test pin 67 or PCM test pin 56 and PCM test pins 24 and 103.

Are both resistances greater than 10,000 ohms?

YES GO to HW22. See: HW21 - HW30
NO REPAIR short circuit. RESTORE vehicle. COMPLETE PCM reset to clear DTCs. RERUN Quick Test.

HW6 - DTC P1443- Monitor Idle Air Control Duty Cycle (IAC At Idle) - Ranger Flexible Fuel EVAP System

Continuous Memory DTC P1443 can be initiated by an IAC valve speed error sometime during vehicle operation. If a Continuous Memory DTC P1507 is receive with the DTC P1443 in Self-Test, GO directly to Pinpoint Test Step KE30. See: KE - Idle Air Control (IAC) Valve Assembly\KE27 - KE30

NOTE: The following overspeed check is to be performed on flexible fuel vehicles.

Key on, engine off.
Connect scan tool.
Access IAC, TP, and RPM PIDs.
With the engine at normal operating temperature, accessories off and at idle, the IAC duty cycle should be between 20% to 45%.
Observe the IAC and RPM PIDs for an indication of a fault while performing the following: While at idle, wiggle the IAC valve connector and vehicle harness between the IAC valve and PCM. A fault is indicated by a sudden increase in RPM and decrease in duty cycle.
Rapidly (or quickly) press and release the throttle several times while looking for slow return to idle (observing the TP PID). This may indicate a sticking valve.

Is a fault indicated?

YES ISOLATE fault and REPAIR as necessary. RESTORE vehicle. COMPLETE PCM reset to clear DTCs. RERUN Quick Test. VERIFY a symptom no longer exists.
NO GO to HW8.

HW7 - DTC P1443- Check The Engine Voltage On The Purge Flow (PF) Sensor Circuit Voltage With The Engine Running

Continuous Memory DTC P1443 indicates an incorrect evaporative system purge control valve flow. Possible causes: Obstructed, open, or cracked hoses between EVAP canister purge valve and intake manifold.
Damaged EVAP canister purge valve.
Damaged PF sensor.
Key off.
Disconnect PF sensor.
Check for loose pins or broken wires by pulling moderately on the PF, VPWR, and PWR GND circuits at PF sensor harness connector.
Repair as necessary.
Reconnect PF sensor.
Connect scan tool.
Key on, engine running.
Access EVAPPF PID.
Key off.

Did the EVAP PF PID fluctuate around 2.50 volts or 1.00 volt in one minute?

YES For voltage from 2.2 to 2.6V: GO to HW18. See: HW11 - HW20
For voltage from 0.99 to 1.1V: GO to HW19. See: HW11 - HW20
NO GO to HW8.

HW8 - DTC P1443- Visual Check Of Evaporative Emission System

Continuous Memory DTC P1443 indicates an Evaporative emission control system or evaporative canister purge valve (mechanical) malfunction. Possible causes: Damaged EVAP canister.
Pinched, plugged, blocked, cracked, cut, or disconnected fuel vapor tubes/hoses between the fuel tank, EVAP canister, EVAP canister purge valve, purge flow (PF) sensor, and the engine intake manifold.
Damaged Evap canister purge valve.
Damaged PF sensor.
EVAP CANISTER PURGE, or PF circuit shorted to VPWR.

NOTE: Fuel saturation of EVAP canister cannot be effectively checked by the canister weight or intensity of odor (smell).

Check for kinked or pinched fuel vapor tubes/hoses between EVAP canister, EVAP canister purge valve, and engine intake manifold.
Check for cracked or smashed EVAP canister.

Is fault indicated?

YES REPAIR fuel vapor tubes/hoses as necessary. If EVAP canister is cracked or smashed, GO to Powertrain Management Emissions Control Systems. If components are replaced, GO to HW42.
NO For Escort/Tracer, Mustang, Thunderbird/Cougar, Ranger, Aerostar: GO to HW11. See: HW11 - HW20
All others: GO to HW9.

HW9 - Check For VPWR Voltage To EVAP Canister Purge Valve

Disconnect EVAP canister purge valve harness connector.
Key on, engine off.
Measure VPWR circuit voltage at WVAP canister purge valve harness connector to battery negative post.
Key off.

Was the voltage greater than 105V?

YES GO to HW10.
NO REPAIR open in circuit. RESTORE vehicle. COMPLETE PCM reset to clear DTCs. RERUN Quick Test.

HW10 - Check For Intake Manifold Vacuum At The Evap Canister While Electrically Cycling The EVAP Canister Purge Valve

Install breakout box, connect PCM to breakout box.
Disconnect fuel vapor hose to EVAP canister purge valve at EVAP canister.
Install a vacuum gauge to open end of fuel vapor hose.
Start engine.
Idle engine for 5 minutes.
Observe the vacuum gauge. Reading must be near 0 kPa (0 in-Hg).
Connect a jumper between PCM test pin 56 and PCM test pin 51 or 103, while engine is still running.
Idle the engine for additional 5 to 10 minutes.
Observe the vacuum gauge.
Key off.

Did the vacuum reading change from near 0 kPa (0 in-Hg) to 33.77 kPa (10 in-Hg) or greater with addition of jumper?

YES REMOVE vacuum gauge. INSPECT the fuel vapor tubes/hoses between the EVAP canister and the EVAP canister purge valve and between the EVAP canister purge valve and the intake manifold for small cracks, splits or holes. REPAIR as necessary. RESTORE vehicle. GO to HW11.
NO REMOVE vacuum gauge. LEAVE the fuel vapor hose from EVAP canister disconnected.
For vacuum readings within 20.26 kPa (6 in-Hg)-33.77 kPa (10 in-Hg): GO to HW12. See: HW11 - HW20
For vacuum readings less than 20.26 kPa (6 in-Hg): GO to HW13. See: HW11 - HW20

the 174 is a lean code

Roy



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