Acura RL. Manual - part 515

Power Steering Pressure (PSP) Switch 

The PSP switch signals the PCM when the power steering load is high. 

FUEL SUPPLY SYSTEM 

Fuel Cutoff Control 

During deceleration with the throttle valve closed, current to the injectors is cut off to improve fuel economy 
at engine speeds over 850 RPM. Fuel cutoff control also occurs when the engine speed exceeds 6,900 RPM, 
regardless of the position of the throttle valve, to protect the engine from over-reving. When the vehicle is 
stopped, the PCM cuts the fuel at engine speeds over 4,000 RPM. On a cold engine, fuel cut occurs at a 
lower engine speed. 

Fuel Pump Control 

When the ignition is turned on, the PCM grounds PGM-FI main relay 2 (FUEL PUMP) which feeds current 
to the fuel pump (fuel pump control module) for 2 seconds to pressurize the fuel system. With the engine 
running, the PCM grounds PGM-FI main relay 2 (FUEL PUMP) and feeds current to the fuel pump (fuel 
pump control module). When the engine is not running and the ignition is on, the PCM cuts ground to PGM-
FI main relay 2 (FUEL PUMP) which cuts current to the fuel pump (fuel pump control module). 

PGM-FI Main Relay 1 (FI MAIN) and 2 (FUEL PUMP) 

PGM-FI main relay 1 (FI MAIN) is energized whenever the ignition switch is ON (II) to supply battery 
voltage to the PCM, power to the injectors, and power for PGM-FI main relay 2 (FUEL PUMP). PGM-FI 
main relay 2 (FUEL PUMP) is energized to supply power to the fuel pump for 2 seconds when the ignition 
switch is turned ON (II), and when the engine is cranking or running. 

Transfer Fuel Pump 

The fuel in the right side of the fuel tank is drawn over to the left side by the transfer fuel pump. 

CATALYTIC CONVERTER SYSTEM 

Warm Up Three Way Catalytic Converter (WU-TWC) and Under-Floor Three Way Catalytic 
Converter (TWC)  

The WU-TWC/TWC converts hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) in 
the exhaust gas to carbon dioxide (CO2), nitrogen (N2), and water vapor. 

WU-TWC  

 

2007 Acura RL 

2005-08 ENGINE PERFORMANCE Fuel and Emissions Systems - RL

  

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Fig. 37: Identifying Catalytic Converter System (WU-TWC) 
Courtesy of AMERICAN HONDA MOTOR CO., INC. 

TWC  

Fig. 38: Identifying Catalytic Converter System (TWC) 
Courtesy of AMERICAN HONDA MOTOR CO., INC. 

EXHAUST GAS RECIRCULATION (EGR) SYSTEM 

Refer to the system diagram to see a functional layout of the system. 

EGR Valve 

The EGR valve lowers peak combustion temperatures and reduces oxides of nitrogen emissions (NOx) by 
recirculating exhaust gas through the intake manifold and into the combustion chambers. 

POSITIVE CRANKCASE VENTILATION (PCV) SYSTEM 

The PCV valve prevents blow-by gasses from escaping into the atmosphere by venting them into the intake 
manifold. 

 

2007 Acura RL 

2005-08 ENGINE PERFORMANCE Fuel and Emissions Systems - RL

  

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© 2005 Mitchell Repair Information Company, LLC. 

Fig. 39: Identifying PCV Valve, Breather Pipe And Intake Manifold 
Courtesy of AMERICAN HONDA MOTOR CO., INC. 

EVAPORATIVE EMISSION (EVAP) CONTROL SYSTEM 

Refer to the system diagram to see a functional layout of the system. 

EVAP Canister 

The EVAP canister temporarily stores fuel vapor from the fuel tank until it can be purged from the EVAP 
canister into the engine and burned. 

EVAP Canister Purge Valve 

When the engine coolant temperature is below 140°F (60°C), the PCM turns off the EVAP canister purge 
valve which cuts vacuum to the EVAP canister. 

Fuel Tank Pressure (FTP) Sensor 

The FTP sensor converts fuel tank absolute pressure into an electrical input to the PCM. 

Fig. 40: Identifying Fuel Tank Pressure (FTP) Sensor, Terminal And Units

 

2007 Acura RL 

2005-08 ENGINE PERFORMANCE Fuel and Emissions Systems - RL

  

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Courtesy of AMERICAN HONDA MOTOR CO., INC.

EVAP Canister Vent Shut Valve 

The EVAP canister vent shut valve is on the EVAP canister. 

The EVAP canister vent shut valve controls the venting of the EVAP canister. 

Fig. 41: Identifying O-Ring And Valve Of EVAP Canister Vent Shut Valve 
Courtesy of AMERICAN HONDA MOTOR CO., INC. 

FUEL CAP WARNING MESSAGE (WITH MULTI-INFORMATION DISPLAY) 

The PCM detects whether the fuel fill cap is loose or missing under certain conditions and alerts the driver 
by showing the information in the multi-information display. If the PCM detects a small volume leak, the 
MIL may come on during the third drive cycle and store a DTC. 

First drive cycle 

During the first drive cycle after a cold start, the PCM alerts the driver to check the fuel fill cap by showing 
a "CHECK FUEL CAP" ('05 model) or "TIGHTEN FUEL CAP" ('06-08 models) message in the multi-
information display (A), and it stores Temporary DTC P0457 "Evaporative Emission (EVAP) System Leak 
Detected/Fuel Fill Cap Loose or Missing". Tightening the fuel cap does not make the message go off 
immediately. 

'05 model 

Fig. 42: Identifying Multi-Information Display (05 Model)

 

2007 Acura RL 

2005-08 ENGINE PERFORMANCE Fuel and Emissions Systems - RL

  

me 

 

Friday, June 05, 2009 2:33:27 PM

Page 58 

© 2005 Mitchell Repair Information Company, LLC.