
SYMPTOM — ENGINE BACKFIRES-Lean Fuel Mixture
CHECK DIAGNOSIS SYSTEM
Check for output of diagnostic code.
(See page FI-22)
Normal code
CHECK FOR VACUUM LEAKS IN AIR
INTAKE LINE
OK
CHECK IGNITION TIMING
1. Short both terminals of the
check connector.
2. Check ignition timing.
STD: 10° BTDC
(w/short terminals of the
check connector)
OK
CHECK COLD START INJECTOR
(See page FI-49)
OK
CHECK FUEL PRESSURE
(See page FI-45)
OK
CHECK INJECTORS
(See page FI-53)
OK
CHECK EFI ELECTRONIC CIRCUIT
USING VOLT/OHMMETER
Malfunction
code(s)
BAD
BAD
BAD
BAD
BAD
BAD
Diagnostic code(s)
(See page FI-22)
1. Oil filler cap
2. Oil level gauge
3. Hose connections
4. PCV hoses
5. EGR system — EGR valve stays open
Ignition system (See page IG-2)
1. Cold start injector
2. Start injector time switch
(See page FI-71)
1. Fuel pump (See page FI-44)
2. Fuel filter
3. Fuel pressure regulator (See page FI-52)
Injectors — clogged
1. Wiring connection
2. Power to ECU
(1) Fusible link
(2) No.1 and No. 2 main relay
3. Air flow meter
4. Water temp. sensor
5. Air temp. sensor
6. Throttle position sensor
7. Injection signal circuit
(1) Injection wirings
(2) Resistor
(3) ECU
(4) Fuel cut signal
8. Oxygen sensor