Toyota 1 MZ–FE Manual page 35

Normal High
High
Low
High High
1MZ–FE ENGINE
Troubleshooting
If the CO/HC concentration does not comply with
regulations, perform troubleshooting in the order
given below.
See the table below for possible causes, and then
inspect and correct the applicable causes if neces–
sary.
Phenomenon
Rough idle
Rough idle
(Fluctuating HC reading)
Rough idle
(Black smoke from exhaust)
– ENGINE MECHANICAL
Causes
1. Faulty ignitions:
Incorrect timing
Fouled, shorted or improperly gapped plugs
Open or crossed high–tension cords
Cracked distributor cap
2. Incorrect valve clearance
3. Leaky EGR valve
4. Leaky intake and exhaust valves
5. Leaky cylinder
1. Vacuum leaks:
PCV hose
EGR valve
Intake manifold
Air intake chamber
Throttle body
IAC valve
Brake booster line
2. Lean mixture causing misfire
1. Restricted air filter
2. Faulty SFI systems:
Faulty fuel pressure regulator
Clogged fuel return line
Defective ECT switch
Faulty ECM
Faulty injector
Faulty throttle position sensor
Faulty volume air flow meter
EG2–35