check engine FORD FESTIVA 1991 Manual Online

Defective distributor centrifugal advanceReplace advance mechanism
Defective distributor vacuum advanceReplace advance unit
Incorrect spark plugs or plug gapCheck gap and/or replace
spark plugs
Faulty choke operationCheck choke and repair as
required
Clogged vacuum passagesRemove restrictions
Improper size or clogged main jetCheck jet size and clean, see
FUEL
Restricted air cleanerCheck filter and replace as
necessary
Defective distributor cap, rotor or coilReplace cap, rotor or coil
Misfire at All Speeds
Defective spark plugsReplace spark plugs
Defective spark plug wiresReplace spark plug wires
Defective distributor cap, rotor, or coilReplace cap, rotor, or coil
Cracked or broken vacuum hosesReplace vacuum hoses
Vacuum leaksRepair vacuum leaks
Fuel lines cloggedRemove restriction
Hesitation
Cracked or broken vacuumReplace vacuum hoses hoses
Vacuum leaksRepair Vacuum leaks
Binding carburetor linkageEliminate binding
Binding throttle linkageEliminate binding
Binding choke linkage or fast idle camEliminate binding
Improper float settingReadjust float setting, see
FUEL
Cracked or broken ignition wiresReplace ignition wires
Rough Idle, Missing or Stalling
Incorrect curb idle or fast idle speedReset idle speed, see see
ENGINE PERFORMANCE
Incorrect basic timingReset ignition timing see
ENGINE PERFORMANCE
Improper idle mixture adjustmentReset idle mixture, see
ENGINE PERFORMANCE
Improper feedback system operationCheck feedback system see
ENGINE PERFORMANCE
Incorrect spark plug gapReset spark plug gap, see
ENGINE PERFORMANCE
Moisture in ignition componentsDry components
Loose or broken ignition wiresReplace ignition wires
Damaged distributor cap or or rotorReplace distributor cap or
rotor
Faulty ignition coilReplace ignition coil
Fuel filter clogged or wornReplace fuel filter
Damaged idle mixture screwReplace idle mixture screw,
see FUEL
Improper fast idle cam adjustmentReset fast idle cam adjustment,
see TUNE- see ENGINE
PERFORMANCE
Improper EGR valve operationReplace EGR valve
Faulty PCV valve air flowReplace PCV valve
Choke binding or improper choke settingReset choke or eliminate
binding
Vacuum leakRepair vacuum leak
Improper float bowl fuel levelReset float adjustment, see
FUEL
Clogged air bleed or idle passagesClean carburetor passages, see
FUEL
Clogged or worn air cleaner filterReplace air filter
Faulty choke vacuum diaphragmReplace diaphragm, see
ENGINE PERFORMANCE
Exhaust manifold heat valve inoperativeReplace heat valve
Improper distributor spark advanceCheck distributor operation
Leaking valves or valve componentsCheck and repair valvetrain
Improper carburetor mountingRemo ve an d remo u n t
carburetor
Excessive play in distributor shaftReplace distributor
Loose or corroded wiring connectionsRepair or replace as required
Engine Surges
Improper PCV valve airflowReplace PCV valve
Vacuum leaksRepair vacuum leaks
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VACUUM PUMP - DIESEL TROUBLE SHOOTING
VACUUM PUMP (DIESEL) TROUBLE SHOOTING CHART
MANUAL TRANSMISSION
MANUAL TRANSMISSION TROUBLE SHOOTING
MANUAL TRANSMISSION/TRANSAXLE TROUBLE SHOOTING
Clogged air bleedsRemove restriction
EGR valve malfunctionReplace EGR valve
Restricted air cleaner filterReplace air filter
Cracked or broken vacuum hosesReplace vacuum hoses
Cracked or broken ignition wiresReplace ignition wires
Vacuum advance malfunctionCheck unit and replace as
necessary
Defective or fouled spark plugsReplace spark plugs
Ping or Spark Knock
Incorrect ignition timingReset ignition timing see
ENGINE PERFORMANCE
Distributor centrifugal or vacuum advance malfunctionCheck operation and replace
as necessary
Carburetor setting too leanReadjust mixture setting, see
ENGINE PERFORMANCE
Vacuum leakEliminate vacuum leak
EGR valve malfunctionReplace EGR valve
Poor Gasoline Mileage
Cracked or broken vacuumReplace vacuum hoses hoses
Vacuum leaksRepair vacuum leaks
Defective ignition wiresReplace wires
Incorrect choke settingReadjust setting, see ENGINE
PERFORMANCE
Defective vacuum advanceReplace vacuum advance
Defective spark plugsReplace spark plugs
Binding carburetor power pistonEliminate binding
Dirt in carburetor jetsClean and/or replace jets
Incorrect float adjustmentReadjust float setting, see
FUEL
Defective power valveReplace power valve, see
ENGINE PERFORMANCE
Incorrect idle speedReadjust idle speed
Engine Stalls
Improper float levelReadjust float level
Leaking needle valve and seatReplace needle valve and seat
Vacuum leaksEliminate vacuum leaks
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
NOTE:Diesel engines m echanical diagnosis is the sam e as gasoline engines for item s such as noisy valves,
bearings, pistons, etc. T he following trouble shooting covers only item s pertaining to diesel engines.
CONDITION & POSSIBLE CAUSECORRECTION
Excessive Noise
Loose pump-to-drive assembly screwsTighten screws
Loose tube on pump assemblyTighten tube
Valves not functioning properlyReplace valves
Oil Leakage
Loose end plugTighten end plug
Bad seal crimpRemove and re-crimp
seal
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
ConditionPossible Cause
Noisy In Forward GearsLow gear oil level, Loose bell housing bolts, Worn bearings or
gears
Clunk On Deceleration (FWD Only)Loose engine mounts, Worn inboard CV joints, Worn differential
pinion shaft, Side gear hub counterbore in case worn oversize
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POWERTRAIN
CLUTCH TROUBLE SHOOTING
BASIC CLUTCH TROUBLE SHOOTING CHART
Gear Clash When Shifting Forward GearsClutch Out Of Adjustment, Shift linkage damaged or out of
adjustment, Gears or synchronizers damaged, Low gear oil level
Transmission Noisy When Moving (RWD Only) Quiet In Neutral
With Clutch EngagedWorn rear outputshaft bearing
Gear RattleWorn bearings, Wrong gear oil, Low gear oil, Worn gears
Steady Ticking At Idle (Increases With RPM)Broken tooth on gear
Gear Clash When Shifting Forward GearsWorn or broken synchronizers
Loud Whine In ReverseNormal condition (1)
Noise When Stepping On ClutchBad release bearing, Worn pilot bearing
Ticking Or Screeching As Clutch Is EngagedFaulty release bearing, Uneven pressure plate fingers
Click Or Snap When Clutch Is EngagedWorn clutch fork, Worn or broken front bearing retainer
Transmission Shifts HardClutch not releasing, Shift mechanism binding, Clutch installed
backwards
Will Not Shift Into One Gear, Shifts Into All OthersBent shift fork, Worn detent balls
Locked Into Gear, Cannot ShiftClutch adjustment, Worn detent balls
Transmission Jumps Out Of GearPilot bearing worn, Bent shift fork, Worn gear teeth or face,
Excessive gear train end play, Worn synchronizers, Missing detent
ball spring, Shift mechanism worn or out of adjustment, Engine or
transmission mount bolts loose or out of adjustment, Transmission
not aligned
Shift Lever RattleWorn shift lever or detents, Worn shift forks, Worn synchronizers
sleeve
Shift Lever Hops Under AccelerationWorn engine or transmission mounts
(1)Most units use spur cut gears in reverse and are noisy
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSECORRECTION
Chattering or Grabbing
Incorrect clutch adjustmentAdjust clutch
Oil, grease or glaze on facingsDisassemble and clean or replace
Lo o se "U" jo in t fl an geSee DRIVE AXLES article
Worn input shaft splineReplace input shaft
Binding pressure plateReplace pressure plate
Binding release leverSee CLUTCH article
Binding clutch disc hubReplace clutch disc
Unequal pressure plate contactReplace worn/misaligned
components
Loose/bent clutch discReplace clutch disc
Incorrect transmission alignmentRealign transmission
Worn pressure plate, disc or flywheelReplace damaged components
Broken or weak pressure springsReplace pressure plate
Sticking clutch pedalLubricate clutch pedal & linkage
Incorrect clutch disc facingReplace clutch disc
Engine loose in chassisTighten all mounting bolts
Failure to Release
Oil or grease on clutch facingsClean or replace clutch clutch
disc
Incorrect release lever or pedal adjustmentSee CLUTCH article
Worn or broken clutch facingsReplace clutch disc
Bent clutch disc or pressure plateReplace damaged components
Clutch disc hub binding on input shaftClean or replace clutch disc
and/or input shaft
Binding pilot bearingReplace pilot bearing
Sticking release bearing sleeveReplace release bearing and/or
sleeve
Binding clutch cableSee CLUTCH article
Defective clutch masterReplace master cylinder
Defective clutch slaveReplace slave cylinder
Air in hydraulic systemBleed hydraulic system
Rattling
Weak or broken release lever springReplace spring and check
alignment
Damaged pressure plateReplace pressure plate
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A "howling" or "whining" noise from the ring and pinion gear can be caused by an improper gear pattern, gear damage, or improper bearing
preload. It can occur at various speeds and driving conditions, or it can be continuous.
Before disassembling axle to diagnose and correct gear ke sure that tires, exhaust, and vehicle trim have been checked as possible causes.
Chuckle
This is a particular rattling noise that sounds like a stick against the spokes of a spinning bicycle wheel. It occurs while decelerating from 40
MPH and usually can be heard until vehicle comes to a complete stop. The frequency varies with the speed of the vehicle.
A chuckle that occurs on the driving phase is usually caused ive clearance due to differential gear wear, or by a damaged tooth on the coast
side of the pinion or ring gear. Even a very small tooth nick or a ridge on the edge of a gear tooth is enough the cause the noise.
This condition can be corrected simply by cleaning the gear tooth nick or ridge with a small grinding wheel. If either gear is damaged or scored
badly, the gear set must be replaced. If metal has broken loose, the carrier and housing must be cleaned to remove particles that could cause
damage.
Knock
This is very similar to a chuckle, though it may be louder, and occur on acceleration or deceleration. Knock can be caused by a gear tooth that
is damaged on the drive side of the ring and pinion gears. Ring gear bolts that are hitting the carrier casting can cause knock. Knock can also be
due to excessive end play in the axle shafts.
Clunk
Clunk is a metallic noise heard when an automatic transmission is engaged in Reverse or Drive, or when throttle is applied or released. It is
caused by backlash somewhere in the driveline, but not necessarily in the axle. To determine whether driveline clunk is caused by the axle,
check the total axle backlash as follows:
1. Raise vehicle on a frame or twinpost hoist so that drive wheels are free. Clamp a bar between axle companion flange and a part of the
frame or body so that flange cannot move.
2. On conventional drive axles, lock the left wheel to keep it from turning. On all models, turn the right wheel slowly until it is felt to be in
Drive condition. Hold a chalk marker on side of tire about 12" from center of wheel. Turn wheel in the opposite direction until it is
again felt to be in Drive condition.
3. Measure the length of the chalk mark, which is the total axle backlash. If backlash is one inch or less, drive axle is not the source of
clunk noise.
Bearing Whine
Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by malfunctioning pinion bearings. Pinion bearings operate at
drive shaft speed. Roller wheel bearings may whine in a similar manner if they run completely dry of lubricant. Bearing noise will occur at all
driving speeds. This distinguishes it from gear whine, which usually comes and goes as speed changes.
Bearing Rumble
Bearing rumble sounds like marbles being tumbled. It is usually caused by a malfunctioning wheel bearing. The lower pitch is because the
wheel bearing turns at only about 1/3 of drive shaft speed.
Chatter On Turns
This is a condition where the entire front or rear of vehicle vibrates when vehicle is moving. The vibration is plainly felt as well as heard. Extra
differential thrust washers installed during axle repair can cause a condition of partial lock-up that creates this chatter.
Axle Shaft Noise
Axle shaft noise is similar to gear noise and pinion bearing whine. Axle shaft bearing noise will normally distinguish itself from gear noise by
occurring in all driving modes (Drive, cruise, coast and float), and will persist with transmission in Neutral while vehicle is moving at problem
speed.
If vehicle displays this noise condition, remove suspect parts, replace wheel seals and install a new set of bearings. Re-evaluate vehicle for
noise before removing any internal components.
Vibration
Vibration is a high-frequency trembling, shaking or grinding condition (felt or heard) that may be constant or variable in level and can occur
during the total operating speed range of the vehicle.
The types of vibrations that can be felt in the vehicle can d into 3 main groups:
Vibrations of various unbalanced rotating parts of the vehicle.
Resonance vibrations of the body and frame structures caused by rotating of unbalanced parts.
Tip-in moans of resonance vibrations from stressed engine or exhaust system mounts or driveline flexing modes.
DRIVE AXLE - RWD TROUBLE SHOOTING
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing. For definitions of listed
noises or sounds, see DRIVE AXLE
- NOISE DIAGNOSIS under POWERTRAIN.
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POWER STEERING TROUBLE SHOOTING
BASIC POWER STEERING TROUBLE SHOOTING CHART
Steering gear adjustment too looseSee MANUAL STEERING
GEAR article
Steering arms loose on knucklesTighten and check steering
linkage
Rack and pinion mounting looseTighten all mounting bolts
Rack and pinion out of adjustmentSee adjustment in STEERING
article
Tie rod end looseTighten and check steering
linkage
Excessive Pitman shaft-to-ball nut lashRepair as necessary
Poor Returnability
Lack of lubricant in ball joint or linkageLubricate and service systems
Binding in linkage or ball jointsSee STEERING LINKAGE
and SUSPENSION article
Improper front end alignmentSee WHEEL ALIGNMENT
article
Improper tire pressureInflate to proper pressure
Tie rod bindingInflate to proper pressure
Shaft seal rubbing shaftSee STEERING COLUMN
article
Excessive Vertical Motion
Improper tire pressureInflate to proper pressure
Tires, wheels or rotors out of balanceBalance tires then check
wheels and rotors
Worn or faulty shock absorbersCheck and replace if necessary
Loose tie rod ends or steeringTighten or replace if necessary
Loose or worn wheel bearingsSee SUSPENSION article
Steering Pulls to One Side
Improper tire pressureInflate to proper pressure
Front tires are different sizesRotate or replace if necessary
Wheel bearings not adjusted properlySee FRONT SUSPENSION
article
Bent or broken suspension componentsSee FRONT SUSPENSION
article
Improper wheel alignmentSee WHEEL ALIGNMENT
article
Brakes draggingSee BRAKES article
Instability
Low or uneven tire pressureInflate to proper pressure
Loose or worn wheel bearingsSee FRONT SUSPENSION
article
Loose or worn idler arm bushingSee FRONT SUSPENSION
article
Loose or worn strut bushingsSee FRONT SUSPENSION
article
Incorrect front wheel alignmentSee WHEEL ALIGNMENT
article
Steering gear not centeredSee MANUAL STEERING
GEARS article
Springs or shockCheck and replace if necessary
Improper cross shaftSee MANUAL STEERING
GEARS article
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSECORRECTION
Rattle or Chucking Noise
Pressure hoses touching engine partsAdjust to proper clearance
Loose Pitman shaftAdjust or replace if necessary
Tie rods ends or Pitman arm looseTighten and check system
Rack and pinion mounts looseTighten all mounting bolts
Free play in worm gearSee POWER STEERING
GEAR article
Loose sector shaft or thrust bearing adjustmentSee POWER STEERING
GEAR
Free play in pot couplingSee STEERING COLUMN
article
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Ties rods or ball joints bindingCheck and replace if necessary
Intermediate shaft joints bindingSee STEERING COLUMN
article
Kinked pressure hosesCorrect or replace if necessary
Loose housing head spanner nutSee POWER STEERING
GEAR article
Damaged valve leverSee POWER STEERING
GEAR article
Sector shaft adjusted too tightSee ADJUSTMENTS in
POWER STEERING GEAR
article
Worm thrust bearing adjusted too tightSee ADJUSTMENTS in
POWER STEERING GEAR
article
Reaction ring sticking in cylinderSee POWER STEERING
GEAR article
Reaction ring sticking in housing headSee POWER STEERING
GEAR article
Steering pump internal leakageSee POWER STEERING
PUMP article
Steering gear-to-column misalignmentSee STEERING COLUMN
article
Lack of lubrication in linkageService front suspension
Lack of lubrication in ball jointsService front suspension
Increased Effort When Turning Wheel Fast Foaming, Milky Power Steering Fluid, Low Fluid Level or Low Pressure
High internal pump leakageSee POWER STEERING
PUMP article
Power steering pump belt slippingAdjust or replace if necessary
Low fluid levelCheck and fill to proper level
Engine idle speed to lowAdjust to correct setting
Air in pump fluid systemSee POWER STEERING
PUMP article
Pump output lowSee POWER STEERING
PUMP article
Steering gear malfunctioningSee POWER STEERING
GEAR article
Wheel Surges or Jerks
Low fluid levelCheck and fill to proper level
Loose fan beltAdjust or replace if necessary
Insufficient pump pressureSee POWER STEERING
PUMP article
Sticky flow control valveSee POWER STEERING
PUMP article
Linkage hitting oil pan at full turnReplace bent components
Kick Back or Free Play
Air in pump fluid systemSee POWER STEERING
PUMP article
Worn poppet valve in steering gearSee POWER STEERING
PUMP article
Excessive over center lashSee POWER STEERING
GEAR article
Thrust bearing out of adjustmentSee POWER STEERING
GEAR article
Free play in pot couplingSee POWER STEERING
PUMP article
Steering gear coupling loose on shaftSee POWER STEERING
PUMP article
Steering disc mounting bolts looseTighten or replace if necessary
Coupling loose on worm shaftTighten or replace if necessary
Improper sector shaft adjustmentSee POWER STEERING
GEAR article
Excessive worm piston side playSee POWER STEERING
GEAR article
Damaged valve leverSee POWER STEERING
GEAR article
Universal joint looseTighten or replace if necessary
Defective rotary valveSee POWER STEERING
GEAR article
No Power When Parking
Sticking flow control valveSee POWER STEERING
PUMP article
Insufficient pump pressure outputSee POWER STEERING
PUMP article
Excessive internal pump leakageSee POWER STEERING
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STEERING COLUMN TROUBLE SHOOTING
BASIC STEERING COLUMN TROUBLE SHOOTING CHART
PUMP article
Excessive internal gear leakageSee POWER STEERING
PUMP article
Flange rubs against gear adjust plugSee STEERING COLUMN
article
Loose pump beltAdjust or replace if necessary
Low fluid levelCheck and add proper amount
of fluid
Engine idle too lowAdjust to correct setting
Steering gear-to-column misalignedSee STEERING COLUMN
article
No Power, Left Turn
Left turn reaction seal "O" ring wornSee POWER STEERING
GEAR article
Left turn reaction seal damaged/missingSee POWER STEERING
GEAR article
Cylinder head "O" ring damagedSee POWER STEERING
PUMP article
No Power, Right Turns
Column pot coupling bottomedSee STEERING COLUMN
article
Right turn reaction seal "O" ring wornSee POWER STEERING
GEAR article
Right turn reaction seal damagedSee POWER STEERING
GEAR article
Internal leakage through piston end plugSee POWER STEERING
GEAR article
Internal leakage through side plugsSee POWER STEERING
GEAR article
Lack of Effort in Turning
Left and/or right reaction seal sticking in cylinder headReplace, see POWER
STEERING GEAR article
Wanders to One Side
Front end alignment incorrectSee WHEEL ALIGNMENT
article
Unbalanced steering gear valveSee POWER STEERING
GEAR article
Low Pressure Due to Steering Pump
Flow control valve stuck or inoperativeSee POWER STEERING
PUMP article
Pressure plate not flat against cam ringSee POWER STEERING
PUMP article
Extreme wear of cam ringReplace and check
adjustments
Scored plate, thrust plate or rotorSee POWER STEERING
PUMP article
Vanes not installed properlySee POWER STEERING
PUMP article
Vanes sticking in rotor slotsSee POWER STEERING
PUMP article
Cracked/broken thrust or pressure plateSee POWER STEERING
PUMP article
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. T he purpose of this T rouble Shooting inform ation is to provide a list
of com m on causes to problem sym ptom s. For m odel-specific T rouble Shooting, refer to SUBJECT ,
DIAGNOST IC, or T EST ING articles available in the section(s) you are accessing.
CONDITION & POSSIBLE CAUSECORRECTION
Noise in Steering
Coupling pulled apartSee STEERING COLUMNS
article
Column not correctly alignedSee STEERING COLUMNS
article
Broken lower jointReplace joint
Horn contact ring notSee STEERING COLUMN
article
Bearing not lubricatedSee STEERING COLUMN
article
Shaft snap ring not properly seatedReseat or replace snap ring
Plastic spherical joint not lubricatedSee STEERING COLUMN
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Back To Article
GENERAL INFORMATION
T ROUBLE SHOOT ING
* PLEASE READ THIS FIRST *
ENGINE PERFORMANCE
TUNE-UP TROUBLE SHOOTING NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
Problem & Possible CauseAction
Carbon Fouled Plugs
C l o gge d Air Fil t e rReplace Air Filter
Incorrect Idle SpeedReset Idle Speed
Faulty Ignition WiringReplace Ignition Wiring
Sticky Valves/Worn Valve SealCheck Valve Train
Fuel Injection OperationCheck Fuel Injection
Wet/Oil Fouled Plugs
Worn Rings/PistonsOverhaul/Replace Engine
Excessive Cylinder WearOverhaul/Replace Engine
Plug Gap Bridged
Combustion Chamber Carbon DepositsClean Combustion
Chamber
Blistered Electrode
Engine OverheatingCheck Cooling System
Loose Spark PlugsClean/Torque Plugs
Over-Advanced TimingReset Timing
Wrong Plug Heat RangeInstall Correct Plug
Melted Electrodes
Incorrect TimingReset Timing
Burned ValvesReplace Valves
Engine OverheatingCheck Cooling System
Wrong Plug Heat RangeInstall Correct Plug
Engine Won't Start
Loose ConnectionsCheck Connections
No PowerCheck Fuses/Battery
Loose/Worn Timing Belt/Chain/GearsCheck Belt/Chain/Gears
Engine Runs Rough
Leaky/Clogged Fuel InjectorsRepair Fuel Injectors
Leaky/Clogged Fuel LinesRepair Fuel Lines
Clogged Fuel FilterReplace Fuel Filter
Incorrect TimingReset Timing/Check
Advance
Faulty Plugs/WiresReplace Plugs/Wires
Uneven CompressionOverhaul/Replace Engine
Poor Acceleration
Incorrect Ignition TimingReset Timing
Leaky ValvesCheck Compression
Component Failure
Spark ArcingReplace Faulty Part
Defective Pick-Up CoilReplace Pick-Up Coil
Defective Ignition CoilReplace Ignition Coil
Defective Control UnitReplace Control Unit
Ignition Diagnosis By Scope Pattern
All Firing Lines Abnormally High
Retarded Ignition TimingReset Ignition Timing
Lean Air/Fuel MixtureAdjust Fuel Mixture
High Secondary ResistanceRepair Secondary
Ign it io n
All Firing Lines Abnormally Low
Rich Air/Fuel MixtureAdjust Air/Fuel Mixture
Arcing Coil WireReplace Coil Wire
Cracked CoilReplace Coil
Low Coil OutputReplace Coil
Low CompressionCheck/Repair Engine
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FUEL INJECTION TROUBLE SHOOTING
Se ve r a l High F ir in g Lin e s
Fuel Mixture UnbalancedCheck Fuel System
EGR Valve Stuck OpenClean/Replace EGR
Valve
High Plug Wire ResistanceReplace Plug Wire
Cracked/Broken PlugsReplace Plugs
Intake Vacuum LeakRepair Leak
Several Low Firing Lines
Fuel Mixture UnbalancedAdjust Fuel Mixture
Plug Wires ArcingReplace Plug Wires
Cracked Coil ArcingReplace Coil
Uneven CompressionCheck/Repair Engine
Faulty Spark PlugsReplace Plugs
Cylinders Not Firing
Cracked Distributor CapReplace Cap
Shorted Plug WiresReplace Plug Wires
Mechanical Engine FaultCheck/Repair Engine
Spark Plugs FouledReplace Plugs
Carbon Track in Distributor CapReplace Cap
Hard Starting
Defective Ignition Coil(s)Replace Coil(s)
Fouled Spark PlugsReplace Plugs
Incorrect TimingReset Ignition Timing
NOTE:T his article is generic in nature and all inform ation does not apply to all vehicles. For vehicle specific
inform ation, see the appropriate articles in the ENGINE PERFORMANCE category.
Problem & Possible CauseAction
Cold Start Valve InoperativeTest Cold Start Valve
Poor Vacuum/Electrical ConnectionRepair Connections
Contaminated FuelTest Fuel for Water/Alcohol
Bad Fuel Pump Relay/CircuitTest Relay/Wiring
Battery Voltage LowCharge/Test Battery
Low Fuel PressureTest Press. Regulator/Pump
No Distributor Reference PulseRepair Ignition System
Coolant Temp. Sensor DefectiveTest Temp. Sensor/Circuit
No Power To InjectorsCheck Injector Fuse/Relay
Hard Starting
Defective Idle Air Control (IAC)Test IAC and Circuit
EGR Valve OpenTest EGR Valve/Control
Circuit
Restricted Fuel LinesInspect/Replace Fuel Lines
Poor MAP Sensor SignalTest MAP Sensor/Circuit
Engine Stalls During Parking ManeuverCheck P.S. Press. Switch
Rough Idle
Dirty Fuel InjectorsClean/Replace Injectors
Poor MAP Sensor SignalTest MAP Sensor/Circuit
Intermittent Fuel Injector OperationCheck Harness Connectors
Erratic Vehicle Speed Sensor InputsHarness Too Close to Plug
Wires
Poor O2 Sensor SignalTest O2 Sensor/Circuit
Faulty PCV SystemCheck PCV Valve and
Hoses
Poor Acceleration
Weak Fuel PumpReplace Fuel Pump
Dirty Fuel InjectorsClean/Replace Injectors
Excessive Intake Valve DepositsClean Intake System
Poor High Speed Operation
Low Fuel Pump VolumeFaulty Fuel Pump/Filter
Poor MAP Sensor SignalTest Speed Sensor/Circuit
Acceleration Ping/Knock
Faulty EGR SystemCheck EGR Valve and
Hoses
Poor Knock Sensor SignalTest Knock Sensor/Circuit
Poor Baro Sensor SignalTest Baro Sensor/Circuit
Improper Ignition TimingAdjust Timing
Engine OverheatingCheck Cooling System
Poor Quality FuelUse Different Fuel
Carbon Build-UpDecarbon Engine
Page 2 of 3 MITCHELL 1 ARTICLE - GENERAL INFORMATION TROUBLE SHOOTING
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GENERAL INFORMATION
Drive Axle Noise Diagnosis
* PLEASE READ THIS FIRST *
UNRELATED NOISES
Some driveline trouble symptoms are also common to the engine, transmission, wheel bearings, tires and other parts of the vehicle. Make sure
that cause of trouble actually is in the drive axle before adjusting, repairing, or replacing any parts.
NON-DRIVE AXLE NOISES
A few conditions can sound just like drive axle noise and have to be considered in pre-diagnosis. The 4 most common noises are exhaust, tires,
CV/universal joints and trim moldings.
In certain conditions, the pitch of exhaust gases may sound like gear whine. At other times, it may be mistaken for a wheel bearing rumble.
Tires, especially radial and snow tires, can have a high-pitched tread whine or roar, similar to gear noise. Also, some non-standard tires with an
unusual tread construction may emit a roar or whine.
Defective CV/universal joints may cause clicking noises or excessive driveline play that can be improperly diagnosed as drive axle problems.
Trim and moldings can also cause a whistling or whining noise. Ensure that none of these components are causing the noise before
disassembling the drive axle.
GEAR NOISE
A "howling" or "whining" noise from the ring and pinion gear can be caused by an improper gear pattern, gear damage, or improper bearing
preload. It can occur at various speeds and driving conditions, or it can be continuous.
Before disassembling axle to diagnose and correct gear noise, make sure that tires, exhaust, and vehicle trim have been checked as possible
causes.
CHUCKLE
This is a particular rattling noise that sounds like a stick against the spokes of a spinning bicycle wheel. It occurs while decelerating from 40
MPH and usually can be heard until vehicle comes to a complete stop. The frequency varies with the speed of the vehicle.
A chuckle that occurs on the driving phase is usually caused by excessive clearance due to differential gear wear, or by a damaged tooth on the
coast side of the pinion or ring gear. Even a very small tooth nick or a ridge on the edge of a gear tooth is enough to cause the noise.
This condition can be corrected simply by cleaning the gear tooth nick or ridge with a small grinding wheel. If either gear is damaged or scored
badly, the gear set must be replaced. If metal has broken loose, the carrier and housing must be cleaned to remove particles that could cause
damage.
KNOCK
This is very similar to a chuckle, though it may be louder, and occur on acceleration of deceleration. Knock can be caused by a gear tooth that
is damaged on the drive side of the ring and pinion gears. Ring gear bolts that are hitting the carrier casting can cause knock. Knock can also be
due to excessive end play in the axle shafts. NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. For m odel-specific inform ation see appropriate articles where
available.
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. For m odel-specific inform ation see appropriate articles where
available.
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. For m odel-specific inform ation see appropriate articles where
available.
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. For m odel-specific inform ation see appropriate articles where
available.
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. For m odel-specific inform ation see appropriate articles where
available.
NOTE:This is GENERAL inform ation. This article is not intended to be specific to any unique situation or
individual vehicle configuration. For m odel-specific inform ation see appropriate articles where
available.
Page 1 of 2 MITCHELL 1 ARTICLE - GENERAL INFORMATION Drive Axle Noise Diagnosis
3/10/2009 http://www.eautorepair.net/app/PrintItems.asp?S0=2097152&S1=0&SG=%7B9B990D68%2D660A%2D45E9%2D8F46%2DE
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