1998 ACURA INTEGRA engine coolant

2.
1.
1.
2.
After the engine stans, the IAC valve opens for a certain time. The amount ol air is increased to raise the idle speed
about 150 - 300 rpm.
When the coolant temperature is low, the IAC valve is opened to obtain the proper fast idle speed. The amount of
bypassed air is thus controlled in relation to the engine coolant temperature.
IDLE SPEEDtrpm,
ENGINECOOLANT TEMPERATURE
140
50
104
40
-1 32
-20 0
176 ('F)
80 fcl
When the idle speed is out of specification and the scan tool does not indicate Diagnostic Trouble Code (DTC) P0505
or P'1508, check the following items:. Adiust the idle speed (see page '11-111)
' ALT FR signal (see page 11-101). Air conditioning signal {seepage'11-102)' Brake switch signal (seepagell-104)
. Starter switch signal (see page 11-1051. A,4 gear position signal (see page 1l 106) (A"/T)
. PSP switch signal (see page 11-108) (USA)
. Fast idle thermo valve (see page 11-110). Hoses and connections. IAC valve and its mounting O rings
ll the above items are normal, substitute a known-good IAC valve and readjust the idle speed (see page 'l I -1 1 l).
lf the idle speed still cannot be adjusted to specification (and the scan tool does not indicate DTC P0505 or P1508) after
IAC valve replacement, substitute a known-good ECM and recheck. lf symptom goes away, replace the original ECM.
11-97

ldle Control System
ldle Control System
i P0505 | fne scan tool indicates Diagnostic Trouble Code (DTC) P0505: ldle control system malfunction,
NOTE: ll DTC Pl508 is stored at the same time as DTC P0505, troubleshoor DTC P1508 first. then troubleshoot DTC P0505.
Possible Cause
. IAC valve mechanical malfunctiorr
. Fast idle thermo valve malfunction (A"/T)
. Throttle body clogged port, improper adjustment
. Intake manifold, gasket leakage
. Intake air hose loose, leakage
a Vacuum hoses leakage
. ECT sensor incorrect output
. Throttle Position sensor incorrect output
Troubleshooting Flowchart
Problem verification:1. Start the engine. Hold theengine at 3,000 rpm wath noload 1in Park or neutral) untilthe radiator fan comes on,then let it idle.2. With the scan tool, check thefollowing items.- Throttle position should beapprox. 10% with the throttle fully closed.Engine coolant tempera-ture should be 116 212F(80 - 100'c).lf they are not within thespec., repair the faulty sensor crrcuft,3 Check the engine speed atidle with no-load conditions:headlights, blower fan, reardefogger, radiator fan, and airconditioner are not operating,
- The MIL has been reported on.- DTC P0505 is stored.
ls it 750 t 50 rpm (81881,
818C1 engines), 800 I 50 rpm(818C5 engine)?
Intermittent failur6, svstsm is OKat this tim€.
ls it 550 rpm (81881,818C1
engines), 600 rpm {818C5enginelor less?
-98
(To page 11'99)(To page 11-99)

ldle Control System
Fast ldle Thermo Valve (A/T model onlylFast ldle I nermo valve (A/ | mooel
Description
To prevent erratic running when the engine is warming
up. it is necessary to raise the idle speed. The fast idle
thermo valve is controlled by a thermowax plunger.
When the engine is cold, the engine coolant surround-
ing the thermowax contracts the plunger, allowing addi
tional air to be bvoassed into the intake manifold so that
the engine idles taster. When the engine reaches operat-
ing temperature, the valve closes. reducing the amount
of air bypassing into the manifold.
FAST IDLE THERMO
VALVE
VALVE
wAx
Inspection
NOTE: The fast idle thermo valve is factory adiusted; it
should not be disassembled.
1. Remove the intake air duct from the throttle body.
2. Start the engine.
3. Put your finger over the lower port in throttle body
and make sure that there is air flow with the engine
cold {engine coolant temperature below 86'F, 30"c).
LOWERPORT
lf there is no air flow, replace the last idle thermo
valve and retest.
Start the engine. Hold the engine at 3,000 rpm with
no load (in Park or neutral) until the radiator fan
comes on, then let it idle.
Check that valve is completely closed. lf not, air suc-
tion can be felt at the lower port in the throttle body.
l{ any suction is felt, the valve is leaking. Check
engine coolant level and for air in the engine
coolant system (see section 10). It OK, replace the
fast idle thermo valve and recheck.
5.
{1.0 kg.m,7.2lbftl
l
11-110
lL.

In
Intake Air System
Throttle Body
$;
Description
The throttle body is of the single barrel side-draft type.
The lower portion of the throttle valve is heated by
engine coolant from the cylinder head. The idle adjusting
screw which increases/decreases bypass air is located on
the top ot the thronle body.
IDLE ADJUSTINGSCREW
THROTTLESTOP SCREW(Non-adjustable)
FAST IDLE
| | .o clearance. THRoTTLE SToP scREw
{ | | _ .lDonotadiust)
| | y:::::::T,"9":::.'"Tl::f ,::i1::"1" fllyll-'n"
VALVE {A/T model onlv}
Inspection
1. Start the engine. Hold the engine at 3,000 rpm with
no load {in Park or neutral) until the radiator fan
comes on, then let it idle.
2. Stop the engine, and check that the throttle cable
operates smoothly without binding or sticking.
. lf the throttle body pon is clogged, clean it with
carburetor cleaner.
. lf there are any abnormalities in the above steps,
check for:
Excessive wear or play in the throttle valve shaft.- Sticky or binding throttle lever at full close posi-
tion.- Clearance between throttle stop screw and throt-
tle lever at fullclose position.
81881, Bl8Cl engines:
There should beno clearance.
818C5 engine:THROTTLE LINK
There should be
throttle valve shaft or if the shaft is binding or sticking.
glL-

(From psge 11-146)
(To page 11-148)
Chack tho vldlum wh.n cold:'1. Disconnscl the vacuum hoseshown from the EVAP controlcanrster ano connect a vacuumgauge to the hose.2. Start the engine and aliow itto idls.NOTE: Engine coolant tem-porat{rre must be below 154"F{68'C} or A/C switch OFF.3. Ouickly raise the engine speedto 3,000 rpm.
lFrom page 11-146)
Check lor an opon in lhe wir€(lG1 lin6l:1. Turn the ignition switch OFF.2. Disconnect the 2P connectorlrom the EVAP control canis-ter vent shut valve.3. Turn the ignition switch ON (ll).
4. Measure voltage between theEVAP control canister vent shutvalve 2P connector terminalNo. 2 and body ground.
Ropair open in the wir6 betweonthe EVAP control canistor v6ntshut valve end the No. 15 ALTER-NATOR SP SENSOR 17.5 Al tu!e.
Ch€ck tor rn op€n in iho wire IVSVline):1. Turn tho ignition switch OFF.2. Reconnect the 2P connectorto the EVAP control canistervent shut valve,3. Turn the ignition switch ON (ll).
4, Measure vo ltage betweenECN/l connector terminals A29and A10.
Repair open in the wire beiwa€nthe EVAP cont.ol cenister ventshut valve and the EcM {4291.ls there baftery vohage?
ReDlacs tho EVAP cont.ol canis"ter vent shut valve.
EVAP CONTROLCANISTER VENT SHUIVALVE 2P CONNECTOR IC224)
.FJ.\1121-T rcl
(D (BLK/YEL)
I
Wire side ot female terminals
ECM CONNECIOR A {32P}
VSV ILT GRNI
Wire side of femaletermtnars
VACUUMPUMP/GAUGE,0 - 30 in.H94973X -
0a1 - xxxxx
(cont'd )
11-147
PG1 (BLKI
rl
4lq-r'rri l12t5t6t?l8r@llzzlzslul
25212a2
__l

Description
Elestronic Control System (cont'd)
. GRADE LOGIC CONTROL SYSTEM
How it works:
The TCM compares actual driving conditions with driving conditions memorized in the TCM. based on th€ input from the
vehicle speed sensor, throttle position sensor, engine coolant temperature sensor, barometric pressure sensor, bral(e
switch signal and shift lever position signal, to control shifting while a vehicle is ascending or descending a slope, or
reducing speed.
SIGNALS DETECTED
{l
{
Driving ResistanceJudgement of Controlling Aroa
. Ascending mode(Fuzzy logicl. Gl.dual Ascending mode' Steop Asconding mode' oesconding mode. Gradu.l D$conding modo. Slecp D$conding modo
\-t {t

'.J
THROTTLErcsm0NSENSOR
ENGINECOOLANTTEMPERATURESENSOR
WHT/BLKBLK/RED
820424
OBNREO/BLK
84
J
MAINSHAFI COUNTERSHAFISPEED SENSOR SPfED SENSOR
I SHIFT CONTROL I LOCK -UP CONTBOL
+135Eil,?1o'uo'u' 4i85El,o''P'uo'u'
TCM T6nninal locations
TCM -B l22P)Conn€ctor
VREF IATCHK IBASOSS IAFSA IAFSB IFAS ISCS
----T;- t-T-*
+.. | +.., I + ,+
l+ | J l/vt-l .i{-'1M-l L-{-lr^/t-lt't'/!-?
*\::
r--rr!\.1 -r!\./ rartsurssrot coNTFoL M'DULE tTcMr
ltEltn r' -rrt= t= t? t=
NMSG INC INCSG ISH A ISH B ILC A ILC B
576I101112578I10
151617,/1,/20251214,/1,/171920,/1,/J
TCM -A (26P1 Connector
14-47

Terminal NumberSignalDescriptionMaasuring Conditlons/Tarminal Voliage
424ACCLAir conditioning (Ay'C) clutch relay
control
With A,/C comDressor ON: 0 V
With Ay'C compressor OFF: Battery voltage
A25tG1Power supply systemWith ignition switch ON (ll)r 12 V
426LG1Ground
B1Not used
82BAROS SBarometric pressure sensor signal
input
With ignition switch ON (ll) and depending on
barometric pressure: Approx. 3 V
B3ECTEngine coolant temperature sen-
sor signal input
With ignition switch ON (ll) and depending on
engine coolant tem perature: Approx. 0.1 - 4.8 V
B4TPSThrottle position sensor signal
input
With ignition switch ON (ll) 8nd throttle fully
open: 4.14 - 4.82 V
With ignition switch ON (ll) and throttle fully
closed: 0.44 - 0.56 V
B5VSSVehicle speed sensor signal inputWith ignition switch ON (ll) and front wheels
rotating; Pulsing signal
B6AFSBUpshifvdownshift comparative
signal output
With engine idling: 0 V
At uDshift or downshift: 5 V for an instant
B7AFSAUpshifvdownshift com parative
srgnal output
With engine idling: 0 V
At upshift or downshift: 5 V for an instant
B8NCSGCountershaft speed sensor signal
ground
Always: 0 V
B9NCCountershaft speed sensor signal
Input
Depending on vehicle speed: Pulsing signal
When vehicle is stopped:0 V
B10NMMainshaft speed sensor signal
input
Depending on vehicle speed: Pulsing signal
When vehicle is stoDoed: 0 V
811Not used
812STOP SWBrake switch signal inputWith ignition switch ON {ll) and b.ake pedal
depressed: Battery voltage
With ignition switch ON (lll and brake pedal
released:0 V
813Not used
814scsTiming adjustment
service check signal
With ignition switch ON (ll) and service check
connector oDen:5 V
With ignition switch ON (ll) and service check
connector connected with special tool: 0 V
815Not used
816Not used
817NMSGMainshaft speed sensor signalgroundAlways: 0 V
818Not used
819FASShift acknowledge inputWith engine idling: 5 V
At upshift or downshift: 0 V for an instant
820VBEF+5 V referenceWith ignition switch ON {lll: Approx. 5 V
82'lNot used
Not used
14-49