Service Diagnosis - Mechanical - Jeep 200 Cherokee Service Manual

9 - 10 2.5L ENGINE
DIAGNOSIS AND TESTING (Continued)
CONDITION
ENGINE STALLS OR ROUGH IDLE
ENGINE MISSES ON
ACCELERATION
SERVICE DIAGNOSIS—MECHANICAL
CONDITION
NOISY VALVES/LIFTERS
POSSIBLE CAUSES
12. Faulty ignition coil
1. Carbon build-up on throttle plate
2. Engine idle speed too low
3. Worn or incorrectly gapped spark
plugs
4. Worn or burned distributor rotor
5. Spark plug cables defective or
crossed
6. Faulty coil
7. Intake manifold vacuum leak
8. EGR valve leaking or stuck open
1. Worn or incorrectly gapped spark
plugs
2. Spark plug cables defective or
crossed
3. Dirt in fuel system
4. Burned, warped or pitted valves
5. Faulty coil
ENGINE MECHANICAL DIAGNOSIS CHART
POSSIBLE CAUSES
1. High or low oil level in crankcase
2. Thin or diluted oil
3. Low oil pressure
CORRECTION
12. Test and replace, as necessary
(Refer to Group 8D, ignition system)
1. Remove throttle body and
de-carbon. (Refer to Group 14 for
correct procedures)
2. Check Idle Air Control circuit.
(Refer to Group 14, Fuel System)
3. Replace or clean and re-gap
spark plugs (Refer to group 8D,
Ignition System)
4. Install new distributor rotor
5. Check for correct firing order or
replace spark plug cables. (Refer to
Group 8D, Ignition System for
correct procedures.)
6. Test and replace, if necessary
(Refer to group 8D, Ignition System)
7. Inspect intake manifold gasket
and vacuum hoses. Replace if
necessary (Refer to Group 11,
Exhaust System & Intake Manifold)
8. Test and replace, if necessary
(Refer to group 25, Emission
Control Systems)
1. Replace spark plugs or clean and
set gap. (Refer to group 8D, Ignition
System)
2. Check Idle Air Control circuit.
(Refer to Group 14, Fuel System)
3. Clean fuel system
4. Install new valves
5. Test and replace as necessary
(refer to group 8D, Ignition System)
CORRECTION
1. Check for correct oil level. Adjust
oil level by draining or adding as
needed
2. Change oil (Refer to Engine Oil
Service in this group)
3. Check engine oil level. If ok,
Perform oil pressure test. Refer to
this group for engine oil pressure
test/specifications
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