Toyota Land Cruiser 1988 Repair Manual page 148

EFI SYSTEM - Troubleshooting Fl-17
SYMPTOM- ENGINE BACKFIRES-Lean Fuel Mixture
CHECK DIAGNOSIS SYSTEM Diagnostic code(s) (See pages Fl-24, 25)
Check for output of diagnostic code. Malfunction
(See page Fl~21) code(s)
~
Normal code
CHECK FOR VACUUM LEAKS IN AIR 1. Oil filler cap
INTAKE LINE BAD 2. Oil dipstick
3. Hose connections
4. PCV hose(s)
5. EG R system - EG R valve stays open
!
OK
CHECK IGNITION TIMING Ignition timing- Adjust (See page IG-11)
1. Short terminals TE1 and E1 of the
NO
check connector.
2. Check ignition timing.
Standard: 7" BTDC@ idle
(w/ short circuited
TE1 and E1)
~OK
CHECK COLD START INJECTOR 1. Cold start injector (See page'FI-52)
(See page Fl-47) BAD 2. Cold start injector time switch.
(See page Fl-76)
!
OK
CHECK FUEL PRESSURE
1. Fuel pump (See page Fl-46)
(See page Fl-47) BAD 2. Fuel filter
3. Fuel pressure regulator (See page Fl-55)
!
OK
CHECK INJECTORS
Injectors - Clogged
(See page Fl-57)
BAD
!
OK
CHECK EFI ELECTRONIC CIRCUIT 1. Wiring connection
USING VOLT/OHMMETER
BAD 2. Power to ECU
(See page Fl-27)
(1) Fusible links
(2) Fuses
(3) EFI main relay (See page Fl-74)
3. Air flow meter (See page Fl-66)
4. Water temp. sensor (See page Fl-77)
5. Air temp. sensor (See page Fl-66)
6. Throttle position sensor (See page Fl-68)
7. Injection signal circuit
(1) Injector wiring
(2) Fuel cut RPM (See page Fl-85)
(3) ECU (See page Fl-82)
8. Oxygen sensors (See page Fl-80)