Mazda MX-6 1998, Workshop Manual

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TROUBLESHOOTING [ENGINE CONTROL FS]
STEP INSPECTION
ACTION
4 Note
• The following test is for engine running
rough idle with A/C ON concerns. If other
symptoms exist, go to next step.
Connect pressure gauge to A/C low and high
pressure side lines.
Start engine and run it at idle.
Turn A/C ON.
Measure low side and high side pressures.
Are reading pressures within specification?
zr 0 7 -1 0 REFRIGERANT PRESSURE
CHECK
Yes Go to next step.
No
Check following:
• Refrigerant charging amount.
• A/C pressure switches.
• Additional fan operation.
• A/C relay.
5 Note
• Following test is for engine running rough
with P/S ON. If other symptoms exist, go to
next step.
Disconnect power steering pressure switch
connector.
Measure voltage at power steering pressure
switch connector.
Is voltage greater than 10 V?
Yes
Check power steering pressure switch operation.
No Go to next step.
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 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.
9 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.
1 0
Start engine and disconnect IAC valve
connector.
Does rpm drop or the engine stall? Yes Go to next step.
No Check IAC valve and wiring harness.
1 1
Install fuel pressure gauge between fuel filter
and fuel distributor.
Start engine and run at idle. Measure fuel line
pressure at idle.
Is fuel line pressure correct at idle?
Fuel line pressure
210— 260 kPa
{2.1— 2.6 kgf/cm2, 30— 37 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.
1 2
Visually check for fuel leakage at fuel injector
O-ring, pressure regulator and fuel line.
Service as necessary.
Does fuel line pressure hold 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.
01 - 0 1 A - 1 40