Toyota 7M-GE Repair Manual page 27

EM-20
ENGIN lVlECHAN!CAL -
Engine Tune-up
-.
EM288
c
HC
Aigh
High
High
co
Normal
Low
High
'- ', If the CO concentration is not as specified, adjust the idle
mixture by.furning the idle mixture adjusting screw with
SST.
SST 09243-00020 >
0 If the CO concentration is within specification, this
adjustment is complete.
l
if the CO concentration cannot be corrected by idle
mixture adjustment, see the table below for other possi-
t ble causes.
w
Troubleshooting
SYMPTOMS
Rough idle
.-':I -
Rough idle
(Fluctuating HC reading)
Rough idle
(Black smoke from exhaust
CAUSES
1. Faulty ignition:
0 Incorrect timing
0 Fouled, shorted or improperly gapped plugs
6 Open or crossed high-tension cords
0 Cracked distributor cap
2. Incorrect valve clearance
3. Leaky EGR valve
4. Leaky intake and exhaust valves
5. Lea,kv cvlinder
1. Vacuum leak:
0 Vacuum hose
0 EGR valve
0 Intake manifold (Air intake chamber)
0 Throttle body
l
Cylinder head gasket,
0 Brake booster line
2. Lean mixture causing misfire
1. Restricted air filter
2. Faulty ,EFI system:
0 Faulty pressure regulator
0 Clogged fuel return line
0 Faulty air flow meter
0 Defective water temp. sensor
0 Defective air temp. sensor
0 Faulty ECU
l
Faulty injector
0 Faulty cold start injector
l
Faulty throttle position sensor