JEEP CHEROKEE 1988 Service Repair Manual
Page 1281 of 1378
Loose or worn wheel See WHEEL ALIGNMENT
bearings
Loose or worn tie rod ends See SUSPENSION
Worn upper ball joints See Ball Joint Checking
in SUSPENSION
Worn shock absorbers Replace shock absorbers
Worn strut bushings Replace strut bushings
\
\
\
\
\
\
\
Car Pulls to Mismatched or uneven tires Check tire condition
One Side
Broken or sagging springs See SUSPENSION
Loose or worn strut See SUSPENSION
bushings
Improper wheel alignment See WHEEL ALIGNMENT
Improper rear axle Check rear axle
alignment alignment
Power steering gear See STEERING
unbalanced
Front brakes dragging See BRAKES
\
\
\
\
\
\
\
Abnormal Tire Unbalanced tires Check tire balance &
Wear rotation
Sagging or broken springs See SUSPENSION
Incorrect front end See WHEEL ALIGNMENT
alignment
Faulty shock absorbers Replace chock absorbers
\
\
\
\
\
\
\
Scuffed Tires Toe-In incorrect See WHEEL ALIGNMENT
Suspension arm bent or See appropriate
twisted SUSPENSION article
\
\
\
\
\
\
\
Springs Bottom Bent or broken springs See SUSPENSION
or Sag
Leaking or worn shock Replace shock absorbers
absorbers
Frame misalignment Check frame for damage
\
\
\
\
\
\
\
Spring Noises Loose "U" Bolts See SUSPENSION
Loose or worn bushings See SUSPENSION
Worn or missing interliners See SUSPENSION
\
\
\
\
\
\
\
Shock Absorber Loose shock mountings Check & tighten
Noise mountings
Worn bushings Replace bushings
Page 1282 of 1378
Air in system Bleed air from system
Undercoating on shocks Remove undercoating
\
\
\
\
\
\
\
Car Leans or Loose stabilizer bar See SUSPENSION
Sways on Corners
Faulty shocks or mountings Replace shocks or
mountings
Broken or sagging springs See SUSPENSION
\
\
\
\
\
\
\
Shock Absorbers Worn seals or reservoir See SUSPENSION
Leaking tube crimped
\
\
\
\
\
\
\
Broken Springs Loose "U" bolts See SUSPENSION
Inoperative shock absorbers Replace shock absorbers
\
\
\
\
\
\
\
WHEEL ALIGNMENT TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
BASIC WHEEL ALIGNMENT TROUBLE SHOOTING CHART
\
\
\
\
\
\
\
CONDITION POSSIBLE CAUSE CORRECTION \
\
\
\
\
\
\
Premature Tire Improper tire inflation Check tire pressure
Wear
Front alignment out of See ALIGNMENT SPECS in
tolerance WHEEL ALIGNMENT section
Suspension components worn See SUSPENSION section
Steering system components See STEERING section
worn
Improper standing height See WHEEL ALIGNMENT
Uneven or sagging springs See SUSPENSION section
Bent wheel See WHEEL ALIGNMENT
Improper torsion bar See SUSPENSION section
adjustment
Loose or worn wheel See WHEEL BEARING ADJ.
bearings in SUSPENSION section
Worn or defective shock Replace shock absorbers
Tires out of balance Check tire balance
\
\
\
\
\
\
\
Pulls to One Improper tire inflation Check tire pressure
Side
Brake dragging See BRAKE section
Page 1283 of 1378
Mismatched tires See WHEEL ALIGNMENT
Broken or sagging spring See SUSPENSION section
Broken torsion bar See SUSPENSION section
Power steering valve not See STEERING section
centered
Front alignment out of See WHEEL ALIGNMENT
tolerance section
Defective wheel bearing See WHEEL BEARINGS in
SUSPENSION section
Uneven sway bar links See SUSPENSION section
Frame bent Check for frame damage
Steering system bushing See STEERING section
worn
\
\
\
\
\
\
\
Hard Steering Idler arm bushing too tight See STEERING LINKAGE
in STEERING section
Ball joint tight or seized See SUSPENSION section
Steering linkage too tight See STEERING LINKAGE in
STEERING section
Power steering fluid low Add proper amount of
fluid
Power steering drive belt See STEERING section
loose
Power steering pump See STEERING section
defective
Steering gear out of See STEERING section
adjustment
Incorrect wheel alignment See WHEEL ALIGNMENT
Damaged steering gear See STEERING section
Damaged suspension See SUSPENSION section
Bent steering knuckle or See SUSPENSION section
supports
\
\
\
\
\
\
\
Vehicle Strut rod or control arm See SUSPENSION section
"Wanders" bushing worn
Loose or worn wheel See WHEEL BEARINGS in
bearings SUSPENSION section
Improper tire inflation Check tire pressure
Stabilizer bar missing or See SUSPENSION section
defective
Page 1284 of 1378
Wheel alignment out of See Adjustment in
tolerance WHEEL ALIGNMENT section
Broken spring See SUSPENSION section
Defective shock absorbers Replace shock absorbers
Worn steering & suspension See SUSPENSION section
components
\
\
\
\
\
\
\
Front End Shimmy Tire out of balance/round Check tire balance
Excessive wheel runout See WHEEL ALIGNMENT
Insufficient or improper See WHEEL ALIGNMENT
caster section
Worn suspension or steering See SUSPENSION section
components
Defective shock absorbers Replace shock absorber
Wheel bearings worn or See WHEEL BEARING ADJ.
loose in SUSPENSION section
Power steering reaction See STEERING section
Bracket loose
Steering gear box (rack) See STEERING section
mounting loose
Steering gear adjustment See STEERING section
loose
Worn spherical joints See SUSPENSION section
\
\
\
\
\
\
\
Toe-In Not Lower control arm bent See SUSPENSION section
Adjustable
Frame bent Check frame for damage
\
\
\
\
\
\
\
Camber Not Control arm bent See SUSPENSION section
Adjustable
Frame bent Check frame for damage
Hub & bearing not seated See SUSPENSION section
properly
\
\
\
\
\
\
\
Page 1285 of 1378
\003
TU NE-U P - 4 -C YL
1988 J e ep C hero ke e
1988 Jeep 4 Tune-Up
TUNE-UP
All Models
IDENTIFICATION
ENGINE IDENTIFICATION
Engine can be identified by the 4th character of the Vehicle
Identification Number (VIN). The VIN is stamped on a plate attached to\
top left corner of instrument panel.
ENGINE CODES
\
\
\
\
\
\
\
Engine Code
2.5L (150") TBI .................................................. H\
\
\
\
\
\
\
\
TUNE-UP NOTES
NOTE: When performing tune-up procedures described in this
article, the following notes and precautions must be
followed.
Due to late changes and corrections, always refer to Emission
Control Label in engine compartment before attempting tune-up. If
manual and label differ, always use label specifications.
EPA High Altitude emission standards apply to vehicles sold
in certain areas outside California which have an elevation above 4000
feet.
When performing tune-up on vehicles equipped with catalytic
converter, do not allow or create an engine misfire in one or more
cylinders for an extended period of time. Damage to converter may
occur due to loading converter with unburned fuel.
TESTING
ENGINE COMPRESSION
Test compression with all spark plugs removed, throttle
plates and choke valve wide open and engine at normal operating
temperature. Crank engine through at least 5 compression strokes
before recording reading.
COMPRESSION SPECIFICATIONS
\
\
\
\
\
\
\
Application Specification
Compression Ratio ............................................ 9.2:1
Compression Pressure ................ 155-185 psi (10.9-13.0 kg/cm
)
Max. Variation Between Cylinders ............... 30 psi (2.1 kg/cm) \
\
\
\
\
\
\
SPARK PLUGS
SPARK PLUG TYPE
Page 1286 of 1378
\
\
\
\
\
\
\
Application Champion No.
2.5L ...................................................... RC-12LYC
\
\
\
\
\
\
\
SPARK PLUG SPECIFICATIONS \
\
\
\
\
\
\
Application Gap: In. (mm) Torque: Ft. Lbs. (N.m\
)
2.5L .................. .035 (.89) ................... 7-15 (9-20\
)
\
\
\
\
\
\
\
HIGH TENSION WIRE RESISTANCE
Do not puncture spark plug wires with any type of probe.
Remove spark plug wire and check resistance with an ohmmeter.
ADJUSTMENTS
VALVE ARRANGEMENT
* E-I-I-E-E-I-I-E (Front-to-rear).
VALVE CLEARANCE
All models are equipped with hydraulic lifters, which should
be adjusted to zero lash.
IGNITION COIL WIRE
Remove ignition coil wire from coil and distributor cap.
Check terminals for corrosion and clean if necessary. Check coil wire
resistance. Replace wire if resistance is excessive.
HIGH TENSION WIRE RESISTANCE (OHMS)
\
\
\
\
\
\
\
Wire Length (In.) Minimum Maximum\
0-15 ........................ 3000 ........................ 10,000
15-25 ....................... 4000 ........................ 15,000
25-35 ....................... 6000 ........................ 20,000
Over 35 ..................... 8000 ........................ 25,000
\
\
\
\
\
\
\
DISTRIBUTOR
All models are equipped with a Renix solid state ignition
module. Renix system uses a TDC sensor mounted near the flywheel. The
distributor consists of a cap and rotor. Its only function is to
distribute high voltage to appropriate spark plug. No adjustments are
required on either system.
Page 1287 of 1378
Fig. 1: 2.5L Firing Order & Distributor Rotation
IGNITION TIMING
NOTE: No adjustment is possible on models with Renix ignition.
HOT (SLOW) IDLE RPM
NOTE: Adjust ISC motor plunger only after replacing ISC motor.
Idle Speed Control (ISC) Motor Plunger
1) Remove air cleaner, turn off A/C (if equipped) and warm
engine to normal operating temperature. Connect tachometer negative
lead to diagnostic connector terminal "D1-3" and positive lead to
connector terminal "D1-1". See Fig. 2. Turn ignition off. ISC plunger
should fully extend.
Page 1288 of 1378
Fig. 2: TBI Diagnostic Connector & Terminal ID
Courtesy of Chrysler Motors.
2) With plunger extended, disconnect ISC motor electrical
connector. Start engine. Engine idle speed should be 3300-3700 RPM. If
not, turn plunger hex head to obtain 3500 RPM. See Fig. 3.
3) To fully retract ISC motor, hold closed throttle switch
plunger inward while opening throttle. Closed throttle switch plunger
should not touch throttle lever when throttle is closed. If this
occurs, check linkage and/or cable for binding.
Page 1289 of 1378
Fig. 3: TBI Idle Speed Control (ISC) Motor Adjustment
Courtesy of Chrysler Motors.
4) Connect ISC motor connector. Turn ignition off for 10
seconds. ISC motor should fully extend. Restart engine. Engine speed
should momentarily be about 3500 RPM and return to idle speed. Turn
ignition off and disconnect tachometer. Apply sealant to adjustment
screw threads. Install air cleaner.
IDLE SPEED (RPM)
\
\
\
\
\
\
\
Application Curb Idle
2.5L TBI (ISC Plunger Extended) ............................... 3500\
\
\
\
\
\
\
\
NOTE: Holding plunger inward may create an intermittent trouble
code in ECU memory. To clear ECU memory, turn ignition off
and disconnect negative battery cable for 10 seconds.
THROTTLE POSITION SENSOR (TPS) ADJUSTMENT
NOTE: On some models, it may be necessary to remove throttle body
from intake manifold, to access sensor wiring harness.
Automatic Transmission
1) Locate the square TPS connector. Note connector terminal
identification stamped on the back of the connector. Turn ignition on.
2) Connect voltmeter through back of wiring harness
Page 1290 of 1378
connector. Connect negative voltmeter lead to terminal "D" and
positive voltmeter lead to terminal "A" to check input voltage. DO NOT
disconnect TPS connector.
3) Hold throttle plate closed against idle stop and note
voltage. Input voltage should be approximately 5 volts. Disconnect
voltmeter positive lead and connect to terminal "B" to measure output
voltage.
4) With throttle plate closed, measure the output voltage.
The output voltage should be approximately .2 volts. If output voltage
is not within specification, loosen TPS retaining screws.
5) Partially tighten one retaining screw. Rotate TPS to
obtain correct output voltage. Tighten retaining screws once correct
voltage is obtained.
Manual Transmission
1) Turn ignition on. Connect voltmeter through back of wiring
harness connector. Connect negative voltmeter lead to terminal "B" and
positive voltmeter lead to terminal "C". DO NOT disconnect TPS
connector. See Fig. 4.
2) Rotate and hold throttle plate in wide open position.
Ensure throttle linkage contacts stop. Note voltmeter reading. Voltage
reading should be 5 volts at wide open throttle. Return throttle plate
to closed throttle position. Disconnect voltmeter positive lead from
sensor terminal "C" and connect it to terminal "A".
3) Rotate and hold throttle plate in wide open position.
Ensure throttle linkage contacts stop. Note voltmeter reading. Output
voltage should be 4.6-4.7 volts. If voltage is not as specified,
loosen sensor mounting screw. Loosen upper sensor mounting screw for
small adjustments and lower screw for large adjustments.
4) Adjust sensor. Tighten sensor mounting screws. Remove
voltmeter and return throttle plate to closed position. Replace sensor
if specified output voltage cannot be obtained.
Fig. 4: Adjusting Throttle Position Sensor (Man Trans)
Courtesy of Chrysler Motors.
IDLE MIXTURE ADJUSTMENT