Toyota Celica Supra 1986 Service And Repair Manual page 27

ENGINE MECHANICAL - Idle HC/CO Concentration EM·5
IDLE HC/CO CONCENTRATION
NOTE: This check method is used only to deter·
mine whether or not the idle HC/CO complies w ith
re-gulations.
MEASUREMENT
1. RACE ENGINE AT 2.500 RPM FOR ABOUT 2
MINUTES
PRECHECK
INITlAL CONDITIONS
(a) Air cleaner installed
(b) Normal engine operating temperature
C c) All pipes and hoses of air intake system
connected
(d) All accessories switched off
lei All vacuum lines properly connected
NOTE: All vacuum hoses tor EGR systems.
etc. should be properly connected.
(f)
EFI
system wiring connectors
fully
plugged \
Cgl Ignition timing set 'correctly
(h) TransmissiOf'l in N r\ nge
Iii
Tachometer and HC/CO meter calibrat·
ed ond at hand
2 . INSERT TESTING PROBE OF HCICO METER
INTO TAILPIPE AT LEAST 40 em 11.3 ftl
3.
MEASURE HCI CO CONCENTRATION AT IOLE
Wait at least one minute before measuring to
allow the concentration to stabilize.
Complete the measuring within three minutes.
If
the HC/CO concentration does not conform
to your regulations, see the table below for
possible causes.
TROUBLESHOOTING
HC
co
Symptoms
CeUMS
H'gh NOtm&l Rough idlo
I .
Faulty ignition:
•
lncouecc timing
•
Fou~d.
shorted or imptoperly gapped plugs
•
Open or crone<l tgnition wires
•
Cracked distributor cap
2.
Fautw EGA system
•
EGA vatvc
3.
Leaky exhaust valves
4.
Leekv cvllndet
High
Low
Rough idte
I .
Vacuum leak:
Floctuating
•
V.cuum hose
HC reading
•
Intake manifold
2.
t.ean mhtturc causing misfire
High
High
Rough
Idle
1.
Restricced
air filter
8 1aC:k smoke
2.
Faulty EFI system:
ftom exhaust
•
Faulty pressure r89tJl ator
•
Clogged fuel return line
•
Faulty air flow meter
•
D•fecttve w eter temp. s4H\sor
•
Defective air t emp. sensor
•
Faulty ECU
•
Faulty inje<:tor
•
Fa1.1tty cold s-tart injectOr
•
faiJity throttle position sensor