Toyota 4-Runner 1985 Repair Manual page 187

FI-18
EFI SYSTEM -
Troubleshooting
SYMPTOM - ENGINE BACKFIRES-Lean Air Fuel Mixture
CHECK DIAGNOSIS SYSTEM
Check for output of diagnostic code.
(See page F 1·22)
I
Normal code
CHECK FOR VACUUM LEAKS IN AIR
INTAKE LINE
CHECK IGNITION TIMING
STD: 5° BTDC at idle
(T - El Short Circuit)
CHECK COLD START INJECTOR
(See page F 1-47)
CHECK FUEL PRESSURE
(See page FI-43)
~OK
CHECK INJECTORS
(See page FI-50)
CHECK EFI ELECTRONIC CIRCUIT
USING VOL T/OHMMETER
t - - - - -_ _
~Diagnostic
code(s) (See page FI-2S)
Malfunction
code
1 - - - - -__
-11.
Hose connections
BAD 2. PCV hoses
3. EG
R system -
-EG
R valve stays open
Adjust ignition timing
BAD
1 - - - - -_ _ - '
1. Cold start injector
BAD 2. Cold start injector time switch.
(See page FI-67)
t - - - - - - - t
1. Fuel pump (See page FI-42)
BAD 2. Fuel filter
3.
Fuel pressure regulator (See page FI-49)
t - - - - - - - t
Injectors - Clogged
BAD
I-------I~ 1 .
Wiring connection
BAD
2. Power to ECU
(1)
Fusible link
(2)
Main relay
3. Air flow meter
4. Water thermo sensor
5.
Air thermo sensor
6.
Throttle position sensor
7.
Injection signal
(1)
Injection wiring
(2)
Resistor
(3)
ECU
(4)
Fuel cut signal
8. Ox sensor
I