Mazda MX-6 1998, Workshop Manual

Page: 175 / 1282

TROUBLESHOOTING [ENGINE CONTROL FS]
STEP INSPECTION
ACTION
4 Connect NGS tester to DLC.
Access RPM PID, MAF PID, TP V PID, and
VSS PID.
Drive vehicle with monitoring PIDs.
• PRM PID: Engine speed.
• MAF PID.
ef
0 1 -4 0 A MASS AIR FLOW SENSOR
INSPECTION [FS]
• TP V PID.
tr 0 1 -4 0 A THROTTLE POSITION
SENSOR INSPECTION [FS]
• VSS PID.
c r 0 5 -17A VEHICLE SPEED SENSOR
INSPECTION [LA4A-EL]
Are PIDs within specification?
Yes Go to next step.
No RPM PID:
Check CKP sensor and related harness for vibration
and/or intermittent open/short circuit.
MAF PID:
Check for intermittent open circuit of mass air flow sensor
and related wire harness.
TP V PID:
Check if TP sensor output increases smoothly.
VSS PID:
Check for intermittent open circuit of vehicle speed sensor
and related wire harness.
5 Visually inspect crankshaft position (CKP)
sensor and teeth of crankshaft pulley.
Is CKP sensor and teeth of crankshaft pulley
okay?
Yes Go to next step.
No Replace malfunctioning part.
6 Measure gap between CKP sensor and teeth
of crankshaft pulley.
Specification
0.5— 1.5 mm {0.02— 0.05 in}
Is gap within specifications?
Yes Go to next step.
No
Adjust CKP sensor.
7
Check spark plug conditions.
Is spark plug wet, converted with carbon or
grayish white?
Yes If spark plug is wet or converted with carbon, check for
fuel leak from fuel injector.
If spark plug is grayish white, check 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
Are there restrictions in exhaust system?
Yes Check exhaust system.
No Go to next step.
10
Install fuel gauge between fuel filter and fuel
distributor. Connect NGS tester to DLC.
In OUTPUT TEST MODE select “ALL ON”
and press start.
Is fuel line pressure correct with ignition switch
ON?
Fuel line pressure
260— 310 kPa
{2.6— 3.2 kgf/cm2, 37—46 psi}
Yes Go to next step.
No Zero or low:
Check fuel pump circuit.
Check for open fuel pump relief valve.
Check for fuel leak inside pressure regulator.
Check for clogged main fuel line.
High:
Check pressure regulator for high pressure cause.
Check for clogged fuel return line.
11 Note
• Following test is for engine stalling concern
with A/C on concern. If other symptom
exists, go to next step.
Connect pressure gauge to A/C low and high
side pressure lines.
Turn A/C on and measure low and high side
pressures.
Are pressures within specifications?
tr
0 7 -1 0 REFRIGERANT PRESSURE
CHECK
Yes Go to next step.
No Check follows:
• Refrigerant charging amount.
• A/C pressure switches.
• Additional fan operation.
• A/C relay.
1 2
Check for A/C cut off operation.
Does A/C cut-off work properly?
Yes Go to next step.
No Check A/C cut off system.
01-01A -1 47