Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL KL]
STEP INSPECTION ACTION
18 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 specification?
Yes
Go to next step.
No Adjust CKP sensor.
19
Check for cracks on high tension leads.
Is there any crack on high tension leads? Yes
Repair suspected high tension lead.
No Go to next step.
20 Is strong blue spark visible at each
disconnected hightension lead while cranking
engine?
Yes Go to next step.
No Check following(s):
• Open or short circuit in ignition coil.
• Hightension lead(s).
• Open or short circuit in wire harness for ignition system.
• Malfunction of external condenser for eliminating
ignition noise.
• Open circuit between ignition switch and ignition coil.
• Open circuit between ignition coil and PCM.
21 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 injector.
If spark plug is grayish white, check for clogged fuel
injector.
No Install spark plugs on original cylinders.
Go to next step.
22 Disconnect TP sensor connector.
Is there correct voltage at TP sensor
connector terminal A with ignition switch ON?
Specification
4.5— 5.5 V
Yes Go to next step.
No Check short to ground in constant voltage circuit between
TP sensor, EGR boost sensor or fuel tank pressure (FTP)
sensor and powertrain control module.
23 Disconnect NGS tester.
Turn ignition switch on.
Check terminal voltage of FEPS at DLC.
Is reading voltage greater than 9 V?
Yes Check short to power in FEPS line between DLC and
PCM.
No Go to next step.
24 Remove and shake PCV valve.
Does PCV valve rattle?
Yes Go to next step.
No Replace PCV valve.
25 Is there any restriction in exhaust system? Yes Check exhaust system.
No
Go to next step.
26 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 when ignition
switch is cycled ON/OFF five times?
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.
27 Visually check for fuel leakage at fuel injector
O-ring, pressure regulator, and fuel line.
Service as necessary.
Is fuel line pressure held after ignition switch is
turned off?
Fuel line pressure
More than 150 kPa
{1.5 kgf/cm2, 21 psi} for 5 minutes
Yes Go to next step.
No Check pressure regulator diaphragm condition.
If condition is okay, check fuel injector.
If condition is not okay, replace pressure regulator.
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