1996 ACURA RL KA9 fuel pressure

Fuel Supply System

The HDS or the scan tool indicates Diagnostic Trouble Code (DTC) P0171: The fuel system is too lean [Right

Bank (Bank 1)].

The HDS or the scan tool indicates Diagnostic Trouble Code (DTC) P0172: The fuel system is too rich [Right

Bank (Bank 1)].

The HDS or the scan tool indicates Diagnostic Trouble Code (DTC) P0174: The fuel system is too lean [Left Bank

(Bank 2)].

The HDS or the scan tool indicates Diagnostic Trouble Code (DTC) P0175: The fuel system is too rich [Left Bank

(Bank 2)].

Description

By monitoring the Long Term Fuel Trim, long term malfunctions in the fuel system will be detected.

If a
malfunction
has
been detected
during
two
consecutive
trips,
the MIL
will
come
on and DTC
P0171,
P0172, P0174

and/or P0175 will be stored.

NOTE: If some of the DTCs listed below are stored at the same time as DTC P0171, P0172, P0174 and/or P0175, trou-

bleshoot those DTCs first, then troubleshoot DTC P0171, P0172, P0174 and/or P0175.

P0107, P0108, P1128, P1129: MAP Sensor

P0135: Right Primary HO2S Heater (Bank 1, Sensor 1)

P0137, P0138: Secondary HO2S (Sensor 2)

P0141: Secondary HO2S Heater (Sensor 2)

P0155: Left Primary H02S Heater (Bank 2, Sensor 1)

P0401: EGR Flow Insufficient

P0404: EGR Valve Lift Insufficient

P0406: EGR Valve Position Sensor High Voltage

Possible Cause

Fuel Pump insufficient flow/pressure

Fuel Feed Line clogged, leaking

Fuel Pressure Regulator stuck open

Fuel Filter clogged

Injector clogged, air inclusion

Gasoline doesn't meet Owner's Manual spec.

Primary H02S (Sensor 1) deteriorated

EGR System insufficient flow

Exhaust leak

Fuel Pressure Regulator clogged, stuck closed

Fuel Return Pipe clogged

Injector leaking

Gasoline doesn't meet Owner's Manual spec.

Primary HO2S (Sensor 1) deteriorated

EGR System malfunction (too much flow)

EVAP Canister Purge Valve leaking, stuck opened

(cont'd)ProCarManuals.com

PGM-FI System

Fuel Supply System (cont'd)

Troubleshooting Flowchart

— The MIL has been reported on.

— DTC P0171, P0172, P0174 and/

or P0175 are stored.

Check the fuel pressure.

Is the fuel pressure OK?
NO

YES

Check the Primary HO2S:

1. Start the engine. Hold the

engine at 3,000 rpm with no

load (in Park or neutral) until

the radiator fan comes on.

2. Check the right primary or left

primary* H02S (Sensor 1) out-

put voltage with the HDS or

the scan tool.
Is the fuel pressure too high

or too low?
Check the fuel pressure regulator

and fuel return pipe.

LOW

Check the fuel pump, fuel feed

pipe, fuel filter, and fuel pressure

regulator.

Does it stay at less than 0.3 V

or more than 0.6V?
Replace the HO2S.

NO

Check for a sticking or leaking

EVAP canister purge valve:

With a vacuum pump, apply vacu-

um to the EVAP canister purge

valve from the intake manifold

side.

Does it hold vacuum?
Replace the EVAP canister purge

valve.

YES

Check the EGR system. If it is OK,

replace the fuel injectors.

*: P0174 or P0175ProCarManuals.com

Random Misfir e
The HD S o r th e sca n too l indicate s Diagnosti c Troubl e Cod e (DTC ) P0300 , an d
som e o f P120 1 - P120 6 o r som e o f P130 1 - P1306 : Rando m misfire .
Descriptio n
Misfire detectio n i s accomplishe d b y monitorin g th e voltag e o f th e spar k plu g wit h th e spar k plu g voltag e senso r whic h i s
buil t i n to th e ignitio n coil .
If misfirin g stron g enoug h t o damag e th e catalys t i s detected , th e MI L wil l blin k durin g th e tim e o f it s occurrence , an d DT C
P0300 , som e
of DTC s P120 1 throug h P1206 or som e of DTC s P130 1 throug h P1306 will be stored . Then , after misfir e has
ceased , th e MI L wil l com e o n an d sta y o n wheneve r th e ignitio n switc h is O N (II) .
I f misfirin g tha t increase s emission s i s detecte d during two consecutiv e drivin g cycles , th e MI L wil l com e on , an d DT C
P0300 , som e o f DTC s P120 1 throug h P120 6 o r som e o f DTC s P130 1 throug h P130 6 wil l b e stored .
NOTE : I f som e o f th e DTC s liste d belo w ar e store d a t th e sam e tim e a s a misfir e DTC , troubleshoo t thos e DTC s first , the n
troubleshoo t th e misfir e DTC .
P1128 , P1129 : MA P senso r
P0171 , P0172 , P0174 , P0175 : Fue l meterin g
P0401 , P0404 , P0406 : EG R syste m
P0345 , P0349 , P0390 , P0394 , P1336 , P1337 , P1386 , P1387 : CKP/CM P (CKP/CYP ) senso r
P0506 , P0507 : Idl e Contro l Syste m
P0511 : IA C valv e
Possibl e Caus e
Fuel pum p insufficien t fue l pressure , amoun t o f flo w
Fue l lin e clogging , blockage , leakag e
Fue l filte r cloggin g
Fue l pressur e regulato r stuc k ope n
EG R syste m malfunctio n
Ignitio n coi l wir e open , leakag e
Ignitio n contro l modul e malfunctio n
IA C valv e malfunctio n
Fas t idl e therm o valv e malfunctio n
Carbo n deposit s o n valve s
Compressio n lo w
Gasolin e doe s no t mee t Owner' s Manua l spec. , lac k o f fue l
Troubleshootin g
By test-driving , determin e th e condition s during which misfir e occurs . Dependin g o n thes e conditions , tes t i n th e orde r
describe d i n th e tabl e below .
NOTE : I f misfir e doesn' t recur , som e possibl e cause s ar e fue l tha t doesn' t mee t owner' s manua l spec , lac k o f fuel , carbo n
deposit s o n spar k plug , etc .
11-8 5 sectio n 4 section 4
ProCarManuals.com

Evaporative Emission (EVAP) Controls

Description

The evaporative emission controls are designed to minimize the amount of fuel vapor escaping to the atmosphere. The

system consists of the following components:

A. Evaporative Emission (EVAP) Canister

An EVAP canister is used for the temporary storage of fuel vapor until the fuel vapor can be purged from the EVAP

canister into the engine and burned.

B. Vapor Purge Control System

EVAP canister purging is accomplished by drawing fresh air through the EVAP canister and into a port on the throttle

body. The purging vacuum is controlled by the EVAP canister purge valve.

C. Fuel Tank Vapor Control System

When fuel vapor pressure in the fuel tank is higher than the set value of the EVAP two way valve, the valve opens and

regulates the flow of fuel vapor to the EVAP canister.

During refueling, the fuel tank vapor control valve opens with the pressure in the fuel tank, and feeds the fuel vapor to

the EVAP canister.ProCarManuals.com

54. Attach the chain hoist to the engine.

FUEL PRESSURE REGULATOR

29 N-m (3.0 kgf-m, 22 Ibf-ft)

NOTE: Loosen the locknut on the

fuel pressure regulator, then turn

the fuel pressure regulator 180°.ProCarManuals.com

'00 - 01 models:

Vacuum hose No.

LEFT PRIMARY HEATED OXYGEN SENSOR (LEFT PRIMARY

HO2S) (BANK 2, SENSOR 1)

RIGHT PRIMARY HEATED OXYGEN SENSOR (RIGHT
PRIMARY
HO2S) (BANK
1,
SENSOR
1)

SECONDARY HEATED OXYGEN SENSOR (SECONDARY

HO2S) (SENSOR 2)

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR

INTAKE AIR TEMPERATURE (IAT) SENSOR

LEFT KNOCK SENSOR (BANK 2)

RIGHT KNOCK SENSOR (BANK 1)

IDLE AIR CONTROL (IAC) VALVE

IDLE AIR CONTROL (IAC) THERMAL VALVE

THROTTLE BODY

IDLE ADJUSTING SCREW

INJECTOR

FUEL PULSATION DAMPER

FUEL FILTER

FUEL PRESSURE REGULATOR

PRESSURE REGULATOR VACUUM CONTROL SOLENOID

VALVE

FUEL PUMP

FUEL TANK

FUEL TANK VAPOR CONTROL VALVE

FUEL TANK VAPOR RECIRCULATION VALVE

AIR CLEANER

RESONATOR

INTAKE MANIFOLD RUNNER CONTROL (IMRC) CHECK

VALVE
INTAKE MANIFOLD RUNNER CONTROL (IMRC) VACUUM

RESERVOIR

INTAKE MANIFOLD RUNNER CONTROL (IMRC) SOLENOID

VALVE 1

INTAKE MANIFOLD RUNNER CONTROL (IMRC)

DIAPHRAGM 1

INTAKE MANIFOLD RUNNER CONTROL (IMRC) SOLENOID

VALVE 2

INTAKE MANIFOLD RUNNER CONTROL (IMRC)

DIAPHRAGM 2

EXHAUST GAS RECIRCULATION (EGR) VALVE VACUUM

CONTROL VALVE

EXHAUST GAS RECIRCULATION (EGR) VALVE VACUUM

CONTROL SOLENOID VALVE

EXHAUST GAS RECIRCULATION (EGR) VALVE and POSI-

TION SENSOR

POSITIVE CRANKCASE VENTILATION (PCV) VALVE

EVAPORATIVE EMISSION (EVAP) CANISTER PURGE VALVE

EVAPORATIVE EMISSION (EVAP) CANISTER

EVAPORATIVE EMISSION (EVAP) CANISTER VENT SHUT

VALVE

EVAPORATIVE EMISSION (EVAP) CANISTER FILTER

EVAPORATIVE EMISSION (EVAP) TWO WAY VALVE

EVAPORATIVE EMISSION (EVAP) BYPASS SOLENOID

VALVE

FUEL TANK PRESSURE (FTP) SENSOR

THREE WAY CATALYTIC CONVERTER (TWC)

ENGINE MOUNT CONTROL SOLENOID VALVEProCarManuals.com

PCM Data

You can retrieve data from the PCM by connecting the OBD II scan tool or the Honda PGM Tester to the Data Link

Connector (DLC). The items listed in the table below conform to SAE recommended practice. The Honda PGM Tester also

reads data beyond that recommended by SAE so that this data may help you find the causes of intermittent problems.

NOTE:

• The "operating values" listed are approximate and may vary depending on the environment and the individual vehicle.

• Unless noted otherwise, "at idle speed" means idling with the engine completely warmed up, transmission in Park or

neutral, and the A/C and all accessories turned off.

Data
Description
Operating Value

Freeze Data

Diagnostic

Trouble Code

(DTC)
If the PCM detects a problem, it will store it as a code

consisting of one letter and four numbers.

Depending on the problem, an SAE-defined code

(P0xxx)
or a
Honda-defined code
(P1xxx)
will
be
output

to the tester.
If no problem is detected,

there is no output.

YES

Engine Speed
The PCM computes engine speed from the signals sent

from the Crankshaft Position (CKP) sensor.

This data is used for determining the time and amount

of fuel injection.
Nearly the same as

tachometer indication at

idle speed:

650 ± 50 rpm
YES

Vehicle Speed
The PCM converts pulse signals from the Vehicle

Speed Sensor (VSS) into speed data.
Nearly the same as

speedometer indication
YES

Manifold

Absolute

Pressure (MAP)
The absolute pressure created in the intake manifold by

engine load and speed.
With engine stopped:

Nearly the same as atmo-

spheric pressure.

At idle speed:

24 - 37
kPa
(180
-
280

mmHg, 7.1 - 11.0 inHg)
YES

Engine Coolant

Temperature

(ECT)
The ECT sensor converts coolant temperature into

voltage and signals the PCM. The sensor is a thermistor

whose internal resistance changes with coolant

temperature. The PCM uses the voltage signals from

the ECT sensor to determine the amount of injected

fuel.
With cold engine:

Same as ambient temper-

ature and IAT

With engine warmed up:

approx. 158 - 212°F

(70 - 100°C)
YES

Heated Oxygen

Sensor (HO2S)

(Bank 1, Sensor 1)

(Bank 2, Sensor 1)

(Sensor 2)
The HO2S detects the oxygen content in the exhaust

gas and sends voltage signals to the PCM. Based on

these signals, the PCM controls the air/fuel ratio. When

the oxygen content is high (that is, when the ratio is

leaner than the stoichiometric ratio), the voltage signal

is lower. When the oxygen content is low (that is, when

the ratio is richer than the stoichiometric ratio), the

voltage signal is higher.
0.0 -
1.25
V

At idle speed:

about 0.1 - 0.9 V

NOProCarManuals.com

PGM-FI Syste m
System Descriptio n
INPUTSPOWERTRAI N CONTRO L MODUL E (PCM )OUTPUT S
CKP/CYP Senso r
Cruise
Control
Signal ('04)MA P Senso rECT Senso rIAT Senso rTP Senso rEGR Valv e Positio n Senso rLeft Primar y HO2 SRight Primar y HO2 SSecondar y HO2 SVSSBAR O Senso rLeft Knoc k Senso rRight Knoc k Senso rTCS Signals *VSA Signals*1
Spar k Plu g Voltag e Detectio nModule Signa lStarte r Signa lALT F R Signa lAir Conditionin g Signa lTransmissio n Rang e Switc h Signa lBattery Voltag e (IGN.1 )Brake Peda l Positio n Switc h Signa lPSP Switc h Signa lImmobilize r Signa lFTP Senso rCountershaf t Spee d Senso rMainshaf t Spee d Senso r
Idle Ai r Injecto r Timin g an d Duratio n
Other Contro l Function s
Ignition Timin g Contro l
PCM Back-u p Function s
InjectorsPGM-FI Mai n Rela y (Fue l Pump )Fuel Pum p Rela yMILD4 Indicato r Ligh tIAC Valv eA/C Compresso r Clutc h Rela yICMEVA P Caniste r Purg e Valv eLeft Primar y HO2 S Heate rRight Primar y HO2 S Heate rSecondar y HO2 S Heate rEGR Valv e Vacuu m Contro l Valv ePressur e Regulato r Vacuu mControl Solenoi d Valv eIMRC Solenoi d Valv e 1IMR C Solenoi d Valv e 2DL CTorqu e Converte r Clutc h Solenoi dValveShift Solenoi d Valv eA/T Clutc h Pressur e Contro lSolenoid Valv eEVAP Bypas s Solenoi d Valv eEVAP Caniste r Ven t Shu t Valv eEngin e Moun t Contro l Solenoi dValve
PGM-F I Syste m
Th e PGM-F I syste m o n thi s mode l i s a sequentia l multipor t fue l injectio n system .
Injecto r Timin g an d Duratio n
Th e PC M contain s memorie s fo r th e basi c discharg e duration s a t variou s engin e speed s an d manifol d pressures . Th e
basi c discharg e duration , afte r bein g rea d ou t fro m th e memory , i s furthe r modifie d b y signal s sen t fro m variou s sensor s
t o obtai n th e fina l discharg e duration .
Idl e Ai r Contro l
Idl e Ai r Contro l Valv e (IA C Valve )
Whe n th e engin e i s cold , th e A/ C compresso r i s on , th e transmissio n i s i n gear , th e brak e peda l i s depressed , th e powe r
steerin g loa d i s high , o r th e alternato r i s charging , th e PC M control s curren t t o th e IA C Valv e t o maintai n th e correc t idl e
speed .
Ignition Timin g Contro l
• Th e PC M contain s memorie s fo r basi c ignitio n timin g a t variou s engin e speed s an d manifol d ai r flo w rates . Ignitio n
timin g i s als o adjuste d fo r engin e coolan t temperature .
• A knoc k contro l syste m is als o used . Whe n detonatio n i s detecte d b y a knoc k sensor , th e ignitio n timin g is retarded .
Othe r Contro l Function s
1 . Startin g Contro l
Whe n th e engin e is started , th e PC M provide s a ric h mixtur e b y increasin g injecto r duration .
2 . Fue l Pum p Contro l
• Whe n th e ignitio n switc h i s initiall y turne d on , th e PC M supplie s groun d t o th e PGM-F I mai n rela y tha t supplie s cur -
ren t t o th e fue l pum p fo r 2 second s t o pressuriz e th e fue l system .
• Whe n th e engin e is running , th e PC M supplie s groun d to th e PGM-F I mai n rela y tha t supplie s current to th e fue l pump .
• Whe n th e engin e is no t runnin g an d th e ignitio n i s on , th e PC M cut s groun d t o th e PGM-F I mai n rela y whic h cut s
curren t t o th e fue l pump .
*: wit h TC S*1: wit h VS A
Idle Ai r Contro l
Coolant Temperature Gauge ('04)
ProCarManuals.com