Mazda 626 Station Wagon, Workshop Manual

Page: 144 / 577

TROUBLESHOOTING
STEP INSPECTION RESULTS ACTION
4
Connect NGS tester to DLC.
Access RPM PID, B+ PID, TP V PID,
MAF V PID, and VS PID.
Except for GF4A-EL models
• RPM PID
• B+ PID
• TP V PID
• MAF V PID
• VS PID
For GF4A-EL models
• RPM PID
• VPWR PID
• TP V PID
• MAF PID
• VSS PID
Drive vehicle with monitoring PIDs.
Are PIDs within specification?
(See F1-25 PCM INSPECTION (except for
GF4A-EL models))
(See Section F (for GF4A-EL models))
Yes Go to next step.
No RPM PID:
Inspect CKP sensor and related harness for
such as vibration, intermittent open/short circuit.
B+ (VPWR) PID:
Inspect for open circuit intermittently.
MAF V (MAF) PID:
Inspect for open circuit of MAF sensor and
related wiring harness intermittently.
TP V PID:
Inspect if output signal from TP sensor changes
smoothly.
VS (VSS) PID:
Inspect for open circuit of VSS and related
wiring harness intermittently.
5 Visually inspect CKP sensor and teeth of
crankshaft pulley.
Are CKP sensor and teeth of crankshaft pulley
okay?
Yes Go to next step.
No Replace malfunctioning parts.
6 Measure gap between CKP sensor and teeth of
crankshaft pulley.
Specification
0.5— 1.5 mm {0.020—0.059 in}
Is gap within specification?
Yes Go to next step.
No
Adjust CKP sensor.
7 Inspect spark plug conditions.
Is spark plug wet, covered with carbon or
grayish white?
Yes
Spark plug is wet or covered with carbon:
Inspect for fuel leakage from fuel injector.
Spark plug is grayish white:
Inspect for clogged fuel injector.
No Install spark plugs on original cylinders.
Go to next step.
8 Remove and shake PCV valve.
Does PCV valve rattle? Yes Go to next step.
No
Replace PCV valve.
9 Verify that throttle lever is resting on throttle
valve stop screw and/or throttle valve orifice
plug.
Is lever in correct position?
Yes Go to next step.
No Adjust as necessary.
10 Are there restrictions in the exhaust system? Yes
Inspect exhaust system.
No
Go to next step.
11 Install fuel pressure gauge between fuel main
pipe and fuel distributor.
Connect jumper wire between F/P terminal at
DLC in engine compartment and GND.
Turn ignition switch on.
Is fuel line pressure correct with ignition switch
on?
Fuel line pressure
210—260 kPa {2.1—2.6 kgf/cm2, 30 — 36 psi}
Yes Go to next step.
No Zero or low:
Inspect fuel pump unit circuit.
Inspect for open fuel pump body relief valve.
Inspect for fuel leakage inside pressure
regulator.
Inspect for clogged main fuel line.
Inspect pulsation damper.
High:
Inspect pressure regulator for high pressure
cause.
Inspect for clogged fuel return line.
F1-123