Acura RL. Instruction — page 26

General Description

The fuel tank pressure (FTP) sensor is installed on the evaporative emission (EVAP) canister and detects the
fuel tank pressure. The FTP sensor is used to detect leaks in the EVAP system.

The powertrain control module (PCM) monitors the FTP sensor output voltage. The FTP sensor output
voltage rises as the fuel tank pressure increases. Conversely, the FTP sensor output voltage drops as the fuel
tank pressure decreases. If the FTP sensor output voltage is higher than a target value within a set time after
starting the engine in a cold condition, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status

MONITOR DESCRIPTION CHART

Enable Conditions

ENABLE CONDITIONS

Malfunction Threshold

The output from the fuel tank pressure sensor is more than 8 kPa (2.2 in.Hg, 55 mmHg) for at least 3
seconds.

Driving Pattern

Start the engine in a cold condition, and let it idle until the radiator fan comes on.

Diagnosis Details

Conditions for illuminating the MIL

When a malfunction is detected, the MIL comes on and the DTC and the freeze frame data are stored in the
PCM memory.

Conditions for clearing the MIL

The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the
diagnostic runs.

The MIL, the DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by
disconnecting the battery.

DTC P0455 (90): ADVANCED DIAGNOSTICS

Execution

Once per driving cycle

Sequence

None

Duration

3 seconds or more

DTC Type

One drive cycle, MIL ON

OBD Status

PASSED/FAILED/NOT COMPLETED (STILL TESTING)

Condition

Minimum

Maximum

Elapsed time after starting the engine

2 seconds

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

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Page 101 © 2005 Mitchell Repair Information Company, LLC.

DTC P0455: EVAPORATIVE EMISSION (EVAP) SYSTEM LARGE LEAK DETECTED

Fig. 77: Evaporative Emission System Diagram

Fig. 78: Evaporative Emission System Diagnosis Execution

General Description

The evaporative emission (EVAP) leak detection system uses a vacuum-retention (decompression) method
and an engine off natural vacuum (EONV) method. This method detects leakage by monitoring the vacuum-
retention ability of the EVAP system (from EVAP canister purge valve to fuel tank). The EONV method
detects leakage from the change in fuel tank pressure via the fuel tank pressure (FTP) sensor with the engine
off.

Here is an overview of the malfunction detection for the EONV method:

Step 0: Judgement of detection of 0.09 inch leak as normal operation < decompressing monitor >

Step 1: Judgement of detection of 0.02 inch leak as normal operation < phase 1 >

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2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

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Page 102 © 2005 Mitchell Repair Information Company, LLC.

Step 2: Detection of 0.02 inch leak < phase 2 >

Step 0:

Once required conditions for the monitor are met, the powertrain control module (PCM) applies vacuum to
the EVAP system line from the purge control solenoid (PCS) valve through the fuel tank, and monitors the
variation of the FTP sensor output to detect a «0.09 inch leak».

If a «0.09 inch leak» is detected, it is identified as a malfunction; the diagnosis is complete.

If «no 0.09 inch leak» is detected, the PCM goes to step 1, judgement of detection of a 0.02 inch leak
as normal operation < phase 1 >.

If sufficient vacuum cannot be drawn on the EVAP system line, it is identified as either «EVAP
system low purge flow (P0497)» or «EVAP system leak detected fuel fill cap loose/off (P0457)» (refer
to the applicable DTC detail).

Step 1:

After the engine has stopped, the PCM monitors the variation of the FTP sensor output to detect «no 0.02
inch leak» depending on the variation corresponding to the increasing pressure inside the fuel tank.

If «no 0.02 inch leak» is detected, it is identified as normal; the diagnosis is complete.

If «no 0.02 inch leak» is not detected, the PCM goes to step 2, detection of a 0.02 inch leak < phase 2
>.

Step 2:

The PCM continues to monitor the FTP sensor output to detect «no 0.02 inch leak» depending on the
variation corresponding to the decreasing pressure inside the fuel tank.

If a «0.02 inch leak» is detected, it is identified as a malfunction; the diagnosis is complete.

If «no leakage» is detected, it is identified as normal; the diagnosis is complete.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status

MONITOR DESCRIPTION CHART

Enable Conditions

ENABLE CONDITIONS

Execution

Once per driving cycle

Sequence

None

Duration

45 seconds or less

DTC Type

Two drive cycles, MIL ON

OBD Status

N/A

Condition

Minimum

Maximum

Elapsed time before starting the
engine

6 hours

Initial condition A

(1)

18°F (10°C)

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

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Page 103 © 2005 Mitchell Repair Information Company, LLC.

Malfunction Threshold

The variation of pressure inside the fuel tank is -1.1 kPa (-0.4 in.Hg, -8 mmHg) or more.

Confirmation Procedure with the HDS

Do the EVAP FUNCTION TEST in the INSPECTION MENU with the HDS.

Driving Pattern

1. After the vehicle has been left for an appropriate amount of time as specified, with the engine coolant

temperature and intake air temperature within the specified range, start the engine.

2. Warm up the engine at idle until the radiator fan comes on.

3. Drive the vehicle immediately at a speed between 45 — 75 mph (72 — 120 km/h) for at least 20 minutes.

4. After stopping the engine, turn the ignition switch off, and leave the vehicle for 32 minutes or more

(EONV executes).

Drive the vehicle in this manner only if the traffic regulations and ambient conditions allow.

Diagnosis Details

Initial condition B

(2)

18°F (10°C)

Initial engine coolant temperature 40°F (5°C)

95°F (35°C)

Initial intake air temperature

40°F (5°C)

95°F (35°C)

Engine coolant temperature

156°F (69°C)

212°F (100°C)

Engine coolant temperature
before EVAP purge control starts

140°F (60°C)

Vehicle speed

7 mph (10 km/h)

Barometric pressure

76 kPa (22.5 in.Hg, 569 mmHg) —

Battery voltage

10.5 V

Fuel trim

0.73

1.47

Fuel feedback

Closed loop at stoichiometric

No active DTCs

P0107, P0108, P0111, P0112, P0113, P0116, P0117, P0118,
P0125, P0134, P0135, P0154, P0155, P0335, P0339, P0443,
P0451, P0452, P0453, P0496, P0498, P0499, P1109, P1116,
P1128, P1129, P1172, P1174, P1454, P2195, P2197, P2227,
P2228, P2229, P2237, P2238, P2240, P2241, P2243, P2245,
P2247, P2249, P2251, P2252, P2254, P2255, P2422, P2627,
P2628, P2630, P2631

Others

Other than when there is excessive vapor generation (fuel level is
not full)
Avoid abrupt acceleration, deceleration, and turns
Test-drive on a flat road to avoid misdetection
No refueling is required

(1)

The initial intake air temperature minus the current intake air temperature

(2)

The initial engine coolant temperature minus the initial intake air temperature

2007 Acura RL

2007 ENGINE PERFORMANCE Advanced Diagnostics — RL

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Friday, June 05, 2009 2:32:04 PM

Page 104 © 2005 Mitchell Repair Information Company, LLC.

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