engine overheat FORD FESTIVA 1991 User Guide

TUNE-UP TROUBLE SHOOTING - GAS ENGINE VEHICLES
BASIC SPARK PLUG TROUBLE SHOOTING CHARTS
Faulty solenoid switch, switch connections or relayCheck all wiring between
relay and solenoid or replace
relay or solenoid as necessary
Broken lead or loose soldered connectionsRepair wire or wire
connections as necessary
Solenoid Plunger Vibrates When Switch is Engaged
Weak batteryCharge or replace battery as
necessary
Solenoid contacts corrodedClean contacts or replace
solenoid
Faulty wiringCheck all wiring leading to
solenoid
Broken connections inside switch coverRepair connections or replace
solenoid
Open hold-in wireReplace solenoid
Low Current Draw
Worn brushes or weakReplace brushes or brush
springs as necessary
High Pitched Whine During Cranking Before Engine Fires but Engine Fires and Cranks Normally
Distance too great between starter pinion and flywheelAlign starter or check that
correct starter and flywheel
are being used
High Pitched Whine After Engine Fires With Key released. Engine Fires and Cranks Normally
Distance too small between starter pinion and flywheelFlywheel runout contributes
to the intermittent nature
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
Normal Spark Plug Condition
Light Tan or Gray depositsNo Action
Electrode not burned or fouledNo Action
Gap tolerance not changedNo Action
Cold Fouling or Carbon Deposits
Overrich air/fuel mixtureAdjust air/fuel mixture, see
ENGINE PERFORMANCE
section
Faulty chokeReplace choke assembly, see
ENGINE PERFORMANCE
section
Clogged air filterClean and/or replace air filter
Incorrect idle speed or dirty carburetorReset idle speed and/ or clean
carburetor
Faulty ignition wiresReplace ignition wiring
Prolonged operation at idleShut engine off during long
idle
Sticking valves or worn valve guide sealsCheck valve train
Wet Fouling or Oil Deposits
Worn rings and pistonsInstall new rings and pistons
Excessive cylinder wearRebore or replace block
Excessive valve guide clearanceWorn or loose bearing
Gap Bridged
Deposits in combustion chamber becoming fused to electrodeClean combustion chamber of
deposits
Blistered Electrode
Engine overheatingCheck cooling system
Wrong type of fuelReplace with correct fuel
Loose spark plugsRetighten spark plugs
Over-advanced ignition timingReset ignition timing see
ENGINE PERFORMANCE
Pre-Ignition or Melted Electrodes
Incorrect type of fuelReplace with correct fuel
Incorrect ignition timingReset ignition timing see
ENGINE PERFORMANCE
Burned valvesReplace valves
Engine OverheatingCheck cooling system
Wrong type of spark plug, too hotReplace with correct spark
Page 21 of 36 MITCHELL 1 ARTICLE - GENERAL INFORMATION Trouble Shooting - Basic Procedures
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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
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Let's go back to figuring out dwell/duty readings by using injector on-time specification. This is not generally practical, but we will cover it for
completeness. You NEED to know three things:
Injector mS on-time specification.
Engine RPM when specification is valid.
How many times the injectors fire per crankshaft revolution.
The first two are self-explanatory. The last one may require some research into whether it is a bank-fire type that injects every 360° of
crankshaft rotation, a bank-fire that injects every 720°, or an SFI that injects every 720°. Many manufacturers do not release this data so you
may have to figure it out yourself with a frequency meter.
Here are the four complete steps to convert millisecond on-time:
1. Determine the injector pulse width and RPM it was obtained at. Let's say the specification is for one millisecond of on-time at a hot idle
of 600 RPM.
2. Determine injector firing method for the complete 4 stroke cycle. Let's say this is a 360° bank-fired, meaning an injector fires each and
every crankshaft revolution.
3. Determine how many times the injector will fire at the specified engine speed (600 RPM) in a fixed time period. We will use 100
milliseconds because it is easy to use. Six hundred crankshaft Revolutions Per Minute (RPM) divided by 60 seconds equals 10
revolutions per second. Multiplying 10 times .100 yields one; the crankshaft turns one time in 100 milliseconds. With exactly one
crankshaft rotation in 100 milliseconds, we know that the injector fires exactly one time.
4. Determine the ratio of injector on-time vs. off-time in the fixed time period, then figure duty cycle and/or dwell. The injector fires one
time for a total of one millisecond in any given 100 millisecond period. One hundred minus one equals 99. We have a 99% duty cycle.
If we wanted to know the dwell (on 6 cylinder scale), multiple 99% times .6; this equals 59.4° dwell.
Weaknesses of Dwell/Duty Meter
The weaknesses are significant. First, there is no one-to-one correspondence to actual mS on-time. No manufacturer releases dwell/duty data,
and it is time-consuming to convert the mS on-time readings. Besides, there can be a large degree of error because the conversion forces you to
assume that the injector(s) are always firing at the same rate for the same period of time. This can be a dangerous assumption.
Second, all level of detail is lost in the averaging process. This is the primary weakness. You cannot see the details you need to make a
confident diagnosis.
Here is one example. Imagine a vehicle that has a faulty injector driver that occasionally skips an injector pulse. Every skipped pulse means
that that cylinder does not fire, thus unburned O2 gets pushed into the exhaust and passes the O2 sensor. The O2 sensor indicates lean, so the
computer fattens up the mixture to compensate for the supposed "lean" condition.
A connected dwell/duty meter would see the fattened pulse width but would also see the skipped pulses. It would tally both and likely come
back with a reading that indicated the "pulse width" was within specification because the rich mixture and missing pulses offset each other.
This situation is not a far-fetched scenario. Some early GM 3800 engines were suffering from exactly this. The point is that a lack of detail
could cause misdiagnosis.
As yo u migh t h a ve gu e sse d , a lab scope would not miss this.
RELATIONSHIP BETWEEN DWELL & DUTY CYCLE READINGS
THE TWO TYPES OF INJECTOR DRIVERS
OVERVIEW
There are two types of transistor driver circuits used to operate electric fuel injectors: voltage controlled and current controlled. The voltage
controlled type is sometimes called a "saturated switch" driver, while the current controlled type is sometimes known as a "peak and hold"
driver.
The basic difference between the two is the total resistance of the injector circuit. Roughly speaking, if a particular leg in an injector circuit has
total resistance of 12 or more ohms, a voltage control driver is used. If less than 12 ohms, a current control driver is used.
It is a question of what is going to do the job of limiting the current flow in the injector circuit; the inherent "high" resistance in the injector
circuit, or the transistor driver. Without some form of control, the current flow through the injector would cause the solenoid coil to overheat
and result in a damaged injector.
VOLTAGE CONTROLLED CIRCUIT ("SATURATED SWITCH")
Dwell Meter (2)Duty Cycle Meter
1°1%
15°25%
30°50%
45°75%
60°100%
(1)These are just some examples for your understanding. It is okay to fill in the gaps.
(2)Dwell meter on the six-cylinder scale.
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 4 of 19 MITCHELL 1 ARTICLE - GENERAL INFORMATION Waveforms - Injector Pattern Tutorial
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BRAKE PAD WEAR INDICATOR
CATALYTIC CONVERTER
COOLANT (PROPYLENE-GLYCOL FORMULATIONS)
ELECTROSTATIC DISCHARGE SENSITIVE (ESD) PARTS
ENGINE OIL
FUEL PUMP SHUTOFF SWITCH
This switch stops flow of fuel to engine after a collision. The impact does not have to be great for switch to be triggered. Switch must be reset
after collision. Switch is located under left rear speaker in luggage compartment. Press button to reset switch.
FUEL SYSTEM SERVICE
HALOGEN BULBS
PASSIVE RESTRAINTS
RADIATOR CAP
RADIATOR FAN
WARRANTY INFORMATION
BASIC NEW CAR LIMITED WARRANTY
All parts of the vehicle, except tires, are covered against defects in factory-supplied materials and workmanship for 12 months or 12,000 miles, CAUT ION: Indicator will cause a squealing or scraping noise, warning that brake pads need replacem ent.
CAUT ION: Continued operation of vehicle with a severe m alfunction could cause converter to overheat, resulting
in possible dam age to converter and vehicle.
CAUT ION: T o avoid possible dam age to vehicle use only ethylene-glycol based coolants with a m ixture ratio from
44-68% anti-freeze. DO NOT use 100% anti-freeze as it will cause the form ation of cooling system
deposits. T his results in coolant tem peratures of over 300° F (149°C) which can m elt plastics. 100% anti-
freeze has a freeze point of only -8° F (-22°C).
CAUT ION: Propylene-Glycol Mixtures has a sm aller tem perature range than Ethylene-Glycol. T he tem perature
range (freeze-boil) of a 50/50 Anti-Freeze/Water Mix is as follows: Propylene-Glycol -26° F (-32°C) - 257° F
(125°C) Ethylene-Glycol -35° F (-37°C) - 263° F (128°C)
CAUT ION: Propylene-Glycol/Ethylene-Glycol Mixtures can cause the destabilization of various corrosion inhibitors.
Also Propylene-Glycol/Ethylene-Glycol has a different specific gravity than Ethylene-Glycol coolant,
which will result in inaccurate freeze point calculations.
WARNING:Many solid state electrical com ponents can be dam aged by static electricity (ESD). Som e will display a
warning label, but m any will not. Discharge personal static electricity by touching a m etal ground point
on the vehicle prior to servicing any ESD sensitive com ponent.
CAUT ION: Never use non-detergent or straight m ineral oil.
WARNING:Relieve fuel system pressure prior to servicing any fuel system com ponent (fuel injection m odels).
WARNING:Halogen bulbs contain pressurized gas which m ay explode if overheated. DO NOT touch glass portion
of bulb with bare hands. Eye protection should be worn when handling or working around halogen
bulbs.
CAUT ION: Before operating vehicle, securely fasten passive shoulder restraints to the em ergency release buckles.
T he buckle fits in only one way. Ensure to position it properly.
CAUT ION: Always disconnect the fan m otor when working near the radiator fan. T he fan is tem perature controlled
and could start at any tim e even when the ignition key is in the OFF position. DO NOT loosen or rem ove
radiator cap when cooling system is hot.
WARNING:Keep hands away from radiator fan. Fan is controlled by a therm ostatic switch which m ay com e on or
run for up to 15 m inutes even after engine is turned off.
CAUT ION: Due to the different warranties offered in various regions and the variety of after-m arket extended
warranties available, please refer to the warranty package that cam e with the vehicle to verify all
warranty options.
Page 6 of 9 MITCHELL 1 ARTICLE - MAINTENANCE INFORMATION 1988-93 MAINTENANCE Ford Motor Co. Maintenance Inform...
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Leak in vacuum circuit. Oil pressure incorrect. Manual valve faulty. Band servo faulty. Contaminated fluid. Front clutch faulty. Brake band
out of adjustment or damaged. Leak in hydraulic system.
Transaxle Slips In 1st Gear
Incorrect fluid level. Shift linkage faulty, out of adjustment or incorrectly installed. Incorrect oil pressure. Manual control valve faulty.
Contaminated fluid. Incorrect idle speed. Faulty kickdown solenoid, switch or wiring.
No 1-2 Shift
Shift linkage defective, out of adjustment or incorrectly installed. Leak in vacuum circuit. Faulty kickdown solenoid, switch or wiring.
Contaminated fluid. Manual control valve faulty. Governor valve faulty. Band servo faulty. Brake band out of adjustment. Leak in hydraulic
system. Rear clutch faulty.
No 2-3 Shift
Shift linkage defective, out of adjustment or incorrectly installed. Leak in vacuum circuit. Faulty kickdown solenoid, switch or wiring.
Contaminated fluid. Manual control valve, governor valve or band servo faulty. Leak in hydraulic system. Front clutch faulty.
No Lock-Up
Faulty torque converter, wiring or solenoid.
1-3 Shift; Skips 2nd
Contaminated fluid. Brake band out of adjustment or damaged. Leak in hydraulic system.
No 3-2 Downshift
Leak in vacuum circuit. Manual control valve, governor valve or band servo faulty. Contaminated fluid. Faulty front clutch. Brake band out of
adjustment of damaged. Leak in hydraulic system.
No 2-1 or 3-1 Downshift
Leak in vacuum circuit. Manual control valve, governor valve or band servo faulty. Contaminated fluid. Brake band out of adjustmen t o r
damaged. One-way clutch faulty.
Slippage When Accelerating In 3rd Gear Above Kickdown Speed
Shift linkage damaged, out of adjustment or installed incorrectly. Leak in vacuum circuit. Oil pressure incorrect. Manual control valve or
governor valve faulty. Contaminated fluid. Front clutch faulty. Leak in hydraulic system.
No Kickdown At Normal Speeds In 3rd Gear
Leak in vacuum circuit. Kickdown solenoid, switch or wiring faulty. Manual control valve or governor valve faulty. Contaminated fluid. Brake
band out of adjustment or damaged. Leak in hydraulic system.
1-2 & 2-3 Shift Points Too High
ATF contaminated or level incorrect. Vacuum modulator faulty or leak in vacuum circuit. Line pressures incorrect. Manual valve out of
adjustment. Governor valve faulty. Hydraulic circuit leaking.
3-2 & 2-1 Shift Points Too High
Shift linkage damaged, out of adjustment or incorrectly installed. Kickdown solenoid, switch or wiring faulty. Leak in vacuum circuit.
Incorrect oil pressure. Manual control valve or governor valve faulty. Leak in hydraulic system.
1-2 Or 2-3 Shifts With Shift Lever In "1" Position
Shift linkage damaged, out of adjustment or installed incorrectly. Manual control valve faulty. Leak in hydraulic system.
2-1 or 2-3 Shifts With Shift Lever In "2" Position
Shift linkage damaged, out of adjustment or installed incorrectly. Incorrect oil pressure. Manual control valve faulty.
Vehicle Moves In "P" Or Parking Gear Remains Engaged When
Shifted Out Of "P" Position
Shift linkage damaged, out of adjustment or incorrectly installed. Parking linkage out of adjustment or damaged.
Transaxle Noisy In "P" Or "N" Position
Incorrect fluid level. Incorrect oil pressure. Faulty rear clutch, oil pump, one-way clutch or planetary gear.
Transaxle Noisy In "D", "1", "2" or "R"
Oil pressure incorrect. Rear clutch, oil pump, one-way clutch or planetary gears faulty.
Transmission Overheats
ATF level incorrect. Engine stall speed and/or line pressure incorrect. Faulty band servo, front clutch, rear clutch, brake band, low-reverse
brake, oil pump, torque converter or planetary gear. Leak in hydraulic circuit.
Page 5 of 26 MITCHELL 1 ARTICLE - 1988-94 AUTOMATIC TRANSMISSIONS Ford ATX Overhaul
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