idle air control HONDA INTEGRA 1994 4.G User Guide

PGM-FI System
System Description
ENGINE CONTROL MODULE (ECMIOUTPUTS
PGM-Fl System
The PGM-Fl system on this model is a sequential multipon fuel injection system,
Fuol Iniector Timing and Duration
The ECM contains memories tor the basic discharge durations at various engine speeds and manifold pressures. Thebasic discharge duration, after being read out from the memory, is turther modilied by signals sent from vanous sensofsto obtain the final discharge duration.
ldle Air Control
ldle Air Control Valve (lAC Vatve)
When the engine is cold, the A/C compressor is on, the transmission is in gear (A/T only) the brake pedal is depressed,the P/S load is high, or the alternalor is charging, the ECM controls current to the IAC Valve to maintain correct idle soeed.
lgnition Timing Controla The ECM contains mamories for basic ignition timing at various engine speeds and manifold pressures. lgnition timingis also adjusted for engine coolant temperature.a A Knock Control System is also used. when detonation is detected by the knock sensof. the ignition timing is retarded(B18Cl engine).
Other Control Functions
1. Starting Control
When the engine is started. the ECM provides a rich mixture by increasing fuel injector duration.2. Fuel Pump Control
a When the ignition switch is initially turned on, the ECM supplies ground to the PGM-Fl main relay that suppliescurrent to the fuel pump tor two seconds to pressurize the tuel system.a When the engine is running, the ECM supplies gfound to the PGM-Fl main relay that supplies current to the fuel pump.a When the engine is not running and the ignition is on, the ECM cuts ground to the PGM-FI main relav which cutscurrent to the fuel pump.
TDC/CKP/CYP Sensor
MAP Senso.
ECT Sensor
IAT Sensor
TP Sensor
HO2S
vss
BARO Sensor
ELD
Starter Signal
ALT FR Signal
Air Conditioning Signal
A/T Gear Position Signal
Battery Voltage {lcN. 1)
Brake Switch Signal
PSP Switch Signal
Knock Sensor'
VTEC Pressure Switchr
Fuel-lnjectors
PGM-FI Main Relay (Fuel Pump)
MIL
IAC Valve
A/C Compressor Clutch Relay
Radiator Fan Relav
Condenser Fan Relav
ALT
rcM
EVAP Purge Control Solenoid
HO2S Heater
VTEC Solenoid Valve'
IAB Control Solenoid Valve*
lFuet tnjector Timing and Duration]
I Electr..l"ldle Contr;il
Fit'e' contr; Funcrfit
l6tio; Ttntrlg c..trol
tEcM aack-,rp Functiorlsl
': 818C 1 €ngine
11-40

System Description
The idle speed ot lhe engine is controlled by the ldle Air Control {lAC) Valve.
The valve changes the amount ot air bypassing into the intake manifold in response to electric current controlled by the
ECM. When the IAC Valve is activated, the valve opens to maintain the proper idle speed.
#l' ----rTo FGM-FIMAINRELAY
VARIOUSSENSORS
IAC VALVE
FASTIDLETHERMOVALVE
INTAKE MAI{IFOLD
(cont'd)
BLK
r
11-79

ldle Control System
System Description (cont'd)
1 . Atter the engine slarts. the IAC valve opens for a censin time, The amount ot air is increased to raise the idle soeedabout 15O-3OO rom.
2. When the coolant temperature is low, the IAC valve is opened to obtain the proper fast idle speed. The amount ofbypassed air is thus controlled in relation to the engine coolant temperature.
IDI-E SPEEDlrpm)
176
80
ENGINECOOLANT TEMPERATURE
t"Fl(oct
11-80

ldle Control System
ldle Air Control (lACl Valve
lt6l- -l lf l- The Maltunction Indicator Lamp (MlL) indicates Diagnostic Trouble Code {DTC} 14: A problem in
' '- the ldle Air Control llAC) Valve circuit.
The IAC Valve changes the amount of air bypasEing the throttle body in respons€ to a current signal from the ECM in
order to maintain the proper idle speed.
ffi: r;611/ | /--T-\
- The MIL h.3 been report don,- With tho SCS shon connoctolconnoctod (soo pago 'l 'l -341,
cod6 14 is indicatod.
Do the ECM Reset Procedure (seepage 11-35).
With the engine running snd theaccelerator pedal releas€d, dis-conn€ct th€ 2P connector frorttho IAC valvo.
ls the MIL on and does it indicatecode 14?
htarmitlaot frlu]., aya-t.m i. OK !t thir tlft.
ll.rl drlv. mly ba nac-aaaaryl.Chack tor Doo. conn€c-tlonr oi loora wirca atC3O5 (loc.t.d .t |.ftlhock tow.tl, C424,Cl tB (lAC v.lvol .ndECM.
Disconnect the 2P connector fromthe IAC valve.
Sub.iituto . known{ood IACvdva lnd iotolt.
{To page 11-83}
11-82

ldle Control System
Fast ldle Thermo Valve
DEscliptlon
To prevent erratic running when the engine is warming
up, it is n€cessary to raise the idle speed. The fast idle
thermo valve is controlled by a thermowax plunger, When
the engine is cold. the engine coolant su.rounding the
thermowax contracts the plunger, allowing additional air
to be bypassed into the intake manifold so that the en-
gine idlss taster. When the engine reaches operating tem-
peratur€, the valve closss, reducing the amount of air
bypassing into the manifold.
FAST IDLE THERMOVALVE
AIN EYPASS VALVE
Inspaction
NOTE: The tast idle thermo valve is factory adiustsd;
it should not be disassombl€d.
1. Remove the intake air duct from the throttlg body.
2. Stan the engine.
3. Put your finger over ths lower port in throttle body
and make sure that there is 8ir flow with tho engine
cold (engine coolant temperatute below 86oF,
300c).
a lf not,
retest.
leplace the fast idle thermo valvs and
4.
o-Rr{GsReplace
llo kgf.m, 7 lbt.trl
Start the engine. Hold the sngine at 3.0OO rpm with
no load (A/T in I or @ position, M/T in neutral]
until the radiator fan comes on, then let it idl6.
Check thst valve is completely closed. lt not, air suc-
tion can be telt at the lower Don in the throttle body,
a It any suction is felt, the valve is leaking Check
engine coolant level and for air in tho engine
coolant system (see section 1O). ll OK, rsplace
the fast idle thermo valve and rechock.
11-94

ldle Control System
ldle Speed Setting (cont'd)
10.
9. ldle the engine for one minute with headlights {Low}
ON and check the idle sDeed.
ldla sp6od should bo;
81881 engine:
M/T750 i 50 rpm
An75O t 50 rpm
{in $ or p] positionl
818C1 engine: 75O 1 50 rpm
Turn the headlights off.
ldle the engine for one minute with heater tan switch
at Hl and air conditioner on, then check the idle
speeo.
ldls spood should bo;
81881 ongino:
M/T82O 1 50 rpm
AN840 1 50 rpm(in [N] or lll position)
818C1 engino: 85O t 50 nm
NOTE: lf the idle speed is not within specitication,
see System Troubleshooting Guide on page 1 1-78.
11-96

Intake Air System
System Troubleshooting Guide
NOTE: Across 6ach row in the chart, the sub-systems that could be sources of a symtom are ranked in the order they
should be inspected st8rting with O. Find the symptom in the left column, read across to the most likely source, then
ret€r to the page listod at the top of that column. tf inspection shows the system is OK, try the next system @, etc.
181881 onglnol
't 1-11711-118
WHEN COLD FAST IOLE OUT OF SPEC
WHEN WARM IDLE SPEED TOO HIGH
lB18Cl cngin.l
PAGE I sue-svsreu
_\.-..\
sYMPToM \---...-
THROTTLE
CABLE
THROTTLE
BODY
INTAKE AIR
BYPASS (IAB)
CONTROL
AIR CLEANER
AND INTAKE
AIR DUCT
111191't -12011-1241l117
WHEN COLD FAST IDLE OUT OF SPECo
WHEN WARM IDLE SPEED TOO HIGHoo
LOSS OF POWERo@@
11-115

Intake Air System
System Description
The system supplies air for allengine needs. lt consists of the intake air pipe, Air Cleaner (ACL), intake air duct, Throttle
Body (TB), ldle Air Control {lAC) Valve, tast idle thermo valve, and intake manifold.
A resonator in the intake air pipe provides additional silencing as air is drawn into the system.
nacot{TRoLSOLENOIDVALVE
To
ffi -------------+ i'"ii'i''RELAY
VARIOUSSENSORS
IABCONTROLDIAPHRAGMVALVE
-BLK--L EI{GINE- cooLnnt
tFASTIDLETHERMOVALVE
U
INTAKEAIR PIPE
INTAKEAIRDUCT
11-116

lntake Air System
Throttle Body
Description
The throttle body is ot the single-barrel side-draft 1ype.
The lower portion of the throttle valve is heated by en-gine coolant from the cylinder head. The idle adjusting
screw which increases/dec.eases bvDass air and the
Evaporative Emission (EVAP) Control Canister port are
located on the top of the throttle body.
IOLE AOJUSTING
THROTTLESTOP SCREW(Non-adiustsb16l
11-120
Insoection
CAUTION: Do not adiust the thlottle stop screw. lt ispreset at the lactory.
1. Start the engine. Hold the engine at 3,OOO rpm with
no load (A/T in S or E position, M/T in neutral) until
the radiator fan comes on, then let it idle.
2. Disconnect the vacuum hose (to the EVAP control
canister) from the top of the throttle body; connect
a vacuum, gauge to the throttle body.
VACUUM PUMPGAUGEA973X-O41-XXXXX
5.
3. Allow the engine to idle and check that the gauge
indicates no vacuum.
a li there is vacuum, check the throttle cable (see
page 1 1-'l 18, 119).
Check that vacuum is indicated on the gauge when
the throttle is opened slightly from idle.
a lf the gauge indicates no vacuum, check the throt-
tle body port. lf the throttle body port is clogged.
clean it with carburetor cleaner.
Stop the engine and check that the throttle cable
operates smoothly without binding or sticking.
a lf there are any abnormalities in the above steps,
check for:
- Excessive wear or Dlav in the throttle valve shaft.
Sticky or binding throttle lever at full close po-
srtron.
Clearance between throttle stop screw and throt-
tle lever at tull close Dosition.

Intake
Intake
Air
Air
System
Bypass (lAB) ControlSystem tBl8C1 enginel (cont'dl
Troublcahooting
VACUUII PUMP/GAUG€A973X-041-XXXXX
fromwiro haanasid€
PI{K/BLU I-I
YEI/aLK l+l
tA8 COI{TROLDIAPHRAGM
Insp€ction of IAB Conltol Sytt.m
Start engino and allow to idle.
R€move # 13 vacuum hose tromthe IAB control diaph.agm andconnect vacuum gauge to thehose.
R€move # 12 vacuum hose fromth€ IAB vacuum tank, then checktor vaccum at the IAB vacuumtank.
Rcplir lh. block.g. otvacuufi laak boiwaaotha IAB vacuum tanklnd th. intlk m!ni-fold.
Disconnect the 2P conn€ctor lromthe IAB control solenoid valve.
Measure voltage betweenYEL/BLK (+l torminal andPNK/8LU l-) terminsl.
ls thoro battery voltage?
Measure voltage b€twee nBLK^|/EL (+) torminal and bodyground.
IAB CONTBOLSOLENOID VALVE