Mazda MX-6 1998, Workshop Manual

Page: 355 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION
ACTION
3 Verify diagnostic trouble code of traction
control system.
Is DTC displayed?
Yes
Go to traction control system diagnosis.
tr
04-01 ANTILOCK BRAKE SYSTEM AND
TRACTION CONTROL SYSTEM ON-BOARD
DIAGNOSIS
No Go to next step.
4 Is engine overheating? Yes Go to flowchart 17 for “COOLING SYSTEM CONCERNS
OVERHEATING”.
No Go to next step.
5 Connect NGS tester to DLC.
Access RPM PID, VPWR PID, MAF PID, TP V
PID, and VSS PID.
Drive vehicle with monitoring PIDs.
• VPWR PID: Battery positive voltage
• PRM PID: Idle speed at idle
• MAF PID
tr 01-40B MAF AIR FLOW SENSOR
INSPECTION [KL]
• TP V PID
tr 01-40B THROTTLE POSITION
SENSOR INSPECTION [KL]
• VSS PID
c r 0 5 -1 7B VEHICLE SPEED SENSOR
INSPECTION [KL]
Are PIDs within specification?
Yes Go to next step.
No RPM PID:
Check crankshaft position (CKP) sensor and related
harness; such as vibration, intermittent open/short circuit.
VPWR PID:
Check for open circuit intermittently.
MAF PID:
Check for open circuit of mass air flow sensor and related
wire harness intermittently.
TP V PID:
Check if output signal from throttle sensor changes
smoothly.
VSS PID:
Check for open circuit of vehicle speed sensor and related
wire harness intermittently.
6 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.
7 Measure gap between crankshaft position
(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.
8
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.
9
Remove PCV valve and shake PCV valve.
Does PCV valve rattle? Yes
Go to next step.
No
Replace PCV valve.
10 Check 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.
11 Are there restrictions in exhaust system? Yes Check exhaust system.
No Go to next step.
12
Install fuel gauge between fuel filter and fuel
distributor. Connect NGS tester to DLC.
Select “ALL ON" in OUTPUT TEST MODE
and press start.
Is fuel line pressure correct with ignition switch
ON?
Fuel line pressure
260— 310kP a
{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.
01-01B -149