ESP FORD FESTIVA 1991 User Guide

connector to corresponding terminals on TP sensor connector. Turn ignition on. Measure voltage between TP and SIGRTN terminals on
TP sensor while opening throttle. Compare voltage to specification in TP SENSOR OUTPUT VOLTAGE
table. If voltage is within
specification, repair TP wire to ECA. Go to next step if voltage is not within specification.
3. Turn ignition off. Unplug TP harness connector. Turn ignition on. Measure voltage between VREF and SIGRTN wires on TP harness
connect-or. If voltage is 4-5 volts, replace TP sensor. If voltage is not 4.5-5.5 volts, go to next step.
4. Measure voltage between VREF wire on TP harness connector and ground. If voltage is 4-5 volts, adjust or replace throttle position
sensor. If voltage is not 4-5 volts, go to PINPOINT TEST VREF
.
PINPOINT TEST BP - BAROMETRIC PRESSURE SENSOR

Fig. 12: Identifying BP Sensor Circuits

1.3L
BP sensor is incorporated into ECA; it cannot be checked or serviced separately. If Code 14 is set and cannot be cleared, replace ECA.
1.6L
Turn ignition off. Connect BOB. Remove dust cover from BP sensor, located on passenger side cowl. Turn ignition on. Connect vacuum pump
to BP sensor. Measure voltage between pins BP and SIGRTN on BOB while applying vacuum to BP sensor. See BAROMETRIC
PRESSURE SENSOR OUTPUT VOLTAGE table. Replace BP sensor if voltage is not as specified.
BAROMETRIC PRESSURE SENSOR OUTPUT VOLTAGE
PINPOINT TEST EGO - EXHAUST GAS OXYGEN SENSOR
EGO CIRCUIT PIN IDENTIFICATION
1. Warm engine to operating temperature, and let idle. Unplug EGO sensor. Measure voltage between EGO sensor connector (sensor side) NOTE:Enter this procedure only when a Code 14 is displayed during QUICK T EST S procedure or when
directed here from another PINPOINT T EST . T o prevent unnecessary replacem ent of com ponents, note
following non-EEC item s m ay be at fault: unusually high or low atm ospheric pressure, blocked vacuum
lines, or basic m echanical engine com ponents.
Vacuum (In. Hg.)(1) Voltage
03.84
53.36
102.66
151.93
201.26
25.58
(1)Voltage may vary by 15 percent.
NOTE:Enter this test only when a Code 15 (lean) or Code 17 (rich) is displayed during QUICK TESTS
procedure.
CircuitECA PinBOB PinWire Color
EGO
1.3L2N29BLU
1.6L2D29BLK
Page 13 of 20 MITCHELL 1 ARTICLE - G - TESTS W/CODES 1991-92 ENGINE PERFORMANCE Ford Motor Co. Self-Diagnostics
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Fig. 17: Identifying VPWR Circuit & Connector

VPWR CIRCUIT PIN IDENTIFICATION
1. Turn ignition off. Install BOB, leaving ECA disconnected. Turn ignition on. Measure voltage between VPWR test pin and battery
gr o u n d . If vo l t a ge is n o t gr e a t e r t h a n 1 0 vo l t s, go t o st e p 3). If voltage is greater than 10 volts, go to next step.
2. Measure voltage between VPWR test pin and GROUND test pin. If voltage is greater than 10 volts, go to next step. Repeat measurement
for each ECA ground wire. If all voltages are greater than 10 volts, go to PINPOINT TEST VREF
. If all voltages are not greater than
10 volts, repair ECA ground wire in question.
3. Turn ignition off. Locate main power relay. On Capri, relay is located on left side of engine compartment. On Festiva, relay is located at
left front of engine compartment. Disconnect main power relay 4-wire connector. Using jumper wires, connect BATT, PWR, and GND
terminals of relay to corresponding trammels on connector. Leave VPWR wire disconnected.
4. Turn ignition on. Measure voltage between main power relay VPWR terminal (where VPWR wire was) and ground. If voltage is more
than 10 volts, repair VPWR circuit between main power relay and ECA. If voltage is not more than 10 volts, go to next step.
5. Unplug main relay connector. Measure voltage between harness connector BATT wire and ground. If voltage is not greater than 10
volts, repair BATT wire from battery to harness connector. If voltage is greater than 10 volts, go to next step.
6. Unplug main relay connector. Measure voltage between harness connector PWR wire and ground. If voltage is not greater than 10 volts,
repair PWR wire from ignition switch to harness connector. If voltage is greater than 10 volts, go to next step.
7. Measure voltage between main power relay BATT wire and main power relay GROUND wire. If voltage is less than 10 volts, repair
main power relay ground wire. If voltage is not less than 10 volts, ground circuit is okay; replace main power relay.
PINPOINT TEST VREF - REFERENCE VOLTAGE & SIGNAL RETURN
CircuitECA PinBOB PinWire Color
1.3L
GND2A39, 40, 44, 60BLK
GND2B20BLK
GND2C16BLK
VPWR1B37, 57YEL/BLK
1.6L
GND2R49BLK
GND3A20BLK
GND3G40BLK
VPWR3I37YEL/GRN
NOTE:Enter this test only when directed from another PINPOINT T EST .
Page 18 of 20 MITCHELL 1 ARTICLE - G - TESTS W/CODES 1991-92 ENGINE PERFORMANCE Ford Motor Co. Self-Diagnostics
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gases into harmless substances.
PCV VALVE
The Positive Crankcase Ventilation (PCV) valve, located in the valve cover, controls the flow of blow-by gas from the crankcase to the intake
man ifo l d .
SELF-DIAGNOSTIC SYSTEM
The ECA monitors its inputs and outputs. When it detects a malfunction, it sets a code in the ECA and sends a signal to the CHECK ENGINE
warning light. The light remains on until the malfunction is repaired. Trouble codes may be accessed at the Self-Test Output (STO) and Self-
Test Input (STI) connectors, near the battery.
If a sensor fails, the ECA will use a substitute value in its calculations to permit continued engine operation. In this condition, the vehicle will
run, but driveability may be poor. Intermittent failures may result in the CHECK ENGINE warning light flickering or going out after the fault
goes away. The corresponding trouble code, however, will be stored in the ECA. If fault does not recur, the related code will be erased from
ECA memory.
CHECK ENGINE LIGHT
Hard failures cause the CHECK ENGINE warning light to come on and remain on until the malfunction is repaired. If the warning light comes
on and stays on during vehicle operation, determine and correct the cause of the malfunction. NOTE:For additional inform ation and operating procedures for the self-diagnostic system , refer to T EST S
W/CODES article in the ENGINE PERFORMANCE Section.
Copyr ight 2009 Mitchell Repair Information Company, LLC. All Rights Reserved.
Article GUID: A00022697
Page 6 of 6 MITCHELL 1 ARTICLE - E - THEORY/OPERATION 1991 ENGINE PERFORMANCE Ford/Mercury Theory & Operation
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DRIVE AXLE - NOISE DIAGNOSIS
Unrelated Noises
Some driveline trouble symptoms are also common to the engine, transmission, wheel bearings, tires, and other parts of the vehicle. Ensure
cause of trouble actually is in the drive axle before adjusting, repairing, or replacing any of its 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 wheel trim rings.
In certain conditions, the pitch of the exhaust gases may e gear whine. At other times, it may be mistaken for a wheel bearing rumble.
Tires, especially radial and snow, 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 also can cause a whistling or whining noise. Ensure none of these components are causing the noise before disassembling
the drive axle.
Gear Noise
Broken clutch return springReplace return spring
Worn splines on clutch disc or input shaftReplace clutch disc and/or input
shaft
Worn clutch release bearingReplace release bearing
Dry or worn pilot bearingLubricate or replace pilot bearing
Unequal release lever contactAlign or replace release lever
Incorrect pedal free playAdjust free play
Warped or damaged clutch discReplace damaged components
Slipping
Pressure springs worn orRelease pressure plate
Oily, greasy or worn facingsClean or replace clutch disc
Incorrect clutch alignmentRealign clutch assembly
Warped clutch disc or pressure plateReplace damaged components
Binding release levers or clutch pedalLubricate and/or replace release
components
Squeaking
Worn or damaged releaseReplace release bearing
Dry or worn pilot or release bearingLubricate or replace assembly
Pilot bearing turning in crankshaftReplace pilot bearing and/or
crankshaft
Worn input shaft bearingReplace bearing and seal
Incorrect transmission alignmentRealign transmission
Dry release fork between pivotLubricate release fork and pivot
Heavy and/or Stiff Pedal
Sticking release bearing sleeveReplace release bearing and/or
sleeve
Dry or binding clutch pedal hubLubricate and align components
Floor mat interference with pedalLay mat flat in proper area
Dry or binding ball/fork pivotsLubricate and align components
Faulty clutch cableReplace clutch cable
Noisy Clutch Pedal
Faulty interlock switchReplace interlock switch
Self-adjuster ratchet noiseLubricate or replace self-adjuster
Speed control interlock switchLubricate or replace interlock
switch
Clutch Pedal Sticks Down
Binding clutch cableSee CLUTCH article
Springs weak in pressure plateReplace pressure plate
Binding in clutch linkageLubricate and free linkage
Noisy
Dry release bearingLubricate or replace release
bearing
Dry or worn pilot bearingLubricate or replace bearing
Worn input shaft bearingReplace bearing
Transmission Click
Weak springs in pressureReplace pressure plate plate
Release fork loose on ball studReplace release fork and/or
ball stud
Oil on clutch disc damperReplace clutch disc
Broken spring in slave cylinderReplace slave cylinder
Page 27 of 36 MITCHELL 1 ARTICLE - GENERAL INFORMATION Trouble Shooting - Basic Procedures
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Back To Article
GENERAL INFORMATION
Com puter Relearn Procedures
COMPUTER RELEARN PROCEDURES
Vehicles equipped with engine or transmission computers may require a relearn procedure after vehicle battery is disconnected. Many vehicle
computers memorize and store vehicle operation patterns for optimum driveability and performance. When vehicle battery is disconnected,
this memory is lost. The computer will use default data until new data from each key start is stored. As computer memorizes vehicle operation
for each new key start, driveability is restored. Vehicle computers may memorize vehicles operation patterns for 40 of more key starts.
Customers often complain of driveability problems during relearn stage because vehicle acts differently then before being serviced. Depending
on type and make of vehicle and how it is equipped, the following complaints (driveability problems) may exist:
Harsh Or Poor Shift Quality
Rough Or Unstable Idle
Hesitation Or Stumble
Rich Or Lean Running
Poor Fuel Mileage
These symptoms and complaints should disappear after a number of drive cycles have been memorized. To reduce the possibility of
complaints, after any service which requires battery power to be disconnected, vehicle should be road tested.
GENERIC COMPUTER RELEARN PROCEDURES
Some manufacturers identify a specific relearn procedure which will help establish suitable driveability during relearn stage. These procedures
are especially important if vehicle is equipped with and electronically controlled automatic transmission or transaxle. Always complete
procedure before returning vehicle to customer. The following general procedures are to be used if driveability problems are encountered after
power loss or battery has been disconnected. These procedures may provide an aid in eliminating these problems.
Automatic Transmission
Set parking brake, start engine in "P" or "N" position. Warm-up vehicle to normal operating temperature or until cooling fan cycles.
Allow vehicle to idle for one minute in "N" position. Select "D" and allow engine to idle for one minute.
Accelerate at normal throttle position (20-50%) until vehicle shifts into top gear.
Cruise at light to medium throttle.
Decelerate to a stop, allowing vehicle to downshift, and use brakes normally.
Process may be repeated as necessary.
Manual Transmission
Place transmission in Neutral position.
Ensure emergency brake has been set and all accessories are turned off.
Start engine and bring to normal operating temperature.
Allow vehicle to idle in Neutral for one minute.
Initial relearn is complete, and process will be completed during normal driving.
Copyr ight 2009 Mitchell Repair Information Company, LLC. All Rights Reserved.
Article GUID: A00012612
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Back To Article
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
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Since DVOMs update their display roughly two to five times a second, all measurements in between are averaged. Because a potential voltage
drop is visible for such a small amount of time, it ge t s "a ve r a ge d o u t ", c a u sin g yo u t o miss it .
Only a DVOM that has a "min-max" function that checks EVERY MILLISECOND will catch this fault consistently (if used in that mode). The
Fluke 87 among others has this capability.
A "min-max" DVOM with a lower frequency of checking (100 millisecond) can miss the fault because it will probably check when the injector
is not on. This is especially true with current controlled driver circuits. The Fluke 88, among others fall into this category.
Outside of using a Fluke 87 (or equivalent) in the 1 mS "min-max" mode, the only way to catch a voltage drop fault is with a lab scope. You
will be able to see a voltage drop as it happens.
One final note. It is important to be aware that an injector circuit with a solenoid resistor will always show a voltage drop when the circuit is
energized. This is somewhat obvious and normal; it is a designed-in voltage drop. What can be unexpected is what we already covered--a
voltage drop disappears when the circuit is unloaded. The unloaded injector circuit will show normal battery voltage at the injector.
Remember this and do not get confused.
Checking Injector On-Time With Built-In Function
Several DVOMs have a feature that allows them to measure injector on-time (mS pulse width). While they are accurate and fast to hookup,
they have three limitations you should be aware of:
They only work on voltage controlled injector drivers (e.g "Saturated Switch"), NOT on current controlled injector drivers (e.g. "Peak &
Hold").
A few unusual conditions can cause inaccurate readings.
Varying engine speeds can result in inaccurate readings.
Regarding the first limitation, DVOMs need a well-defined injector pulse in order to determine when the injector turns ON and OFF. Voltage
controlled drivers provide this because of their simple switch-like operation. They completely close the circuit for the entire duration of the
pulse. This is easy for the DVOM to interpret.
The other type of driver, the current controlled type, start off well by completely closing the circuit (until the injector pintle opens), but then
they throttle back the voltage/current for the duration of the pulse. The DVOM understands the beginning of the pulse but it cannot figure out
the throttling action. In other words, it cannot distinguish the throttling from an open circuit (de-energized) condition.
Yet current controlled injectors will still yield a millisecond on-time reading on these DVOMs. You will find it is also always the same,
regardless of the operating conditions. This is because it is only measuring the initial completely-closed circuit on-time, which always takes the
same amount of time (to lift the injector pintle off its seat). So even though you get a reading, it is useless.
The second limitation is that a few erratic conditions can cause inaccurate readings. This is because of a DVOM's slow display rate; roughly
two to five times a second. As we covered earlier, measurements in between display updates get averaged. So conditions like skipped injector
pulses or intermittent long/short injector pulses tend to get "averaged out", which will cause you to miss important details.
The last limitation is that varying engine speeds can result in inaccurate readings. This is caused by the quickly shifting injector on-time as the
engine load varies, or the RPM moves from a state of acceleration to stabilization, or similar situations. It too is caused by the averaging of all
measurements in between DVOM display periods. You can avoid this by checking on-time when there are no RPM or load changes.
A lab scope allows you to overcome each one of these limitations.
Checking Injector On-Time With Dwell Or Duty
If no tool is available to directly measure injector millisecond on-time measurement, some techs use a simple DVOM dwell or duty cycle
functions as a replacement.
While this is an approach of last resort, it does provide benefits. We will discuss the strengths and weaknesses in a moment, but first we will
look at how a duty cycle meter and dwell meter work.
How A Duty Cycle Meter and Dwell Meter Work
All readings are obtained by comparing how long something has been OFF to how long it has been ON in a fixed time period. A dwell meter
and duty cycle meter actually come up with the same answers using different scales. You can convert freely between them. See
RELATIONSHIP BETWEEN DWELL & DUTY CYCLE READINGS TABLE
.
The DVOM display updates roughly one time a second, although some DVOMs can be a little faster or slower. All measurements during this
update period are tallied inside the DVOM as ON time or OFF time, and then the total ratio is displayed as either a percentage (duty cycle) or
degrees (dwell meter).
For example, let's say a DVOM had an update rate of exactly 1 second (1000 milliseconds). Let's also say that it has been measuring/tallying
an injector circuit that had been ON a total of 250 mS out of the 1000 mS. That is a ratio of one-quarter, which would be displayed as 25%
duty cycle or 15° dwell (six-cylinder scale). Note that most duty cycle meters can reverse the readings by selecting the positive o r n e ga t ive
slope to trigger on. If this reading were reversed, a duty cycle meter would display 75%.
Strengths of Dwell/Duty Meter
The obvious strength of a dwell/duty meter is that you can compare injector on-time against a known-good reading. This is the only practical
way to use a dwell/duty meter, but requires you to have known-good values to compare against.
Another strength is that you can roughly convert injector mS on-time into dwell reading with some computations.
A final strength is that because the meter averages everything together it does not miss anything (though this is also a severe weakness that we
will look at later). If an injector has a fault where it occasionally skips a pulse, the meter registers it and the reading changes accordingly.
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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.
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See STALL SPEED SPECIFICATIONS .
Testing Procedures
1. With engine at normal operating temperature, tachometer installed and parking and service brakes applied, perform transaxle stall test in
"D", "2", "1" and "R" ranges at full throttle and note maximum RPM obtained. Correct stall speed should occur at specified RPM. See
the STALL SPEED SPECIFICATIONS
.
STALL SPEED SPECIFICATIONS
2. If stall speed is too high in all shift ranges, the following components may be faulty:
Worn Oil Pump.
Oil leakage from oil pump, valve body or transaxle case.
Sticking pressure regulator valve.
3. If stall speed is too high in "D", "2" and "1", the following component may be faulty:
Slipping rear clutch.
4. If stall speed is too high in "D", the following component may be faulty:
Slipping one-way clutch.
5. If stall speed is too high in "2", the following components may be faulty:
Slipping intermediate band.
6. If stall speed is too high in "R", the following components may be faulty:
Slipping Low/Reverse Clutch.
Slipping Front Clutch.
7. If stall speed is too low in all shift ranges, the following components may be faulty:
Slipping torque converter one-way clutch.
ROAD TEST
1. Before road test, ensure that fluid level, fluid condition and control linkage adjustments are okay. During test, transaxle should upshift
or downshift at about same speed as specified. See appropriate SHIFT SPEED SPECIFICATIONS
.
2. All shifts may vary slightly due to production tolerances or tire size. The quality of the shifts are more important. All shifts should be
smooth, responsive and with no slippage or engine flare. Slippage or engine flare in any gear usually indicates clutch or band problems.
3. The slipping clutch or band in a particular gear can usually be identified by noting transaxle operation in other selector positions and
comparing internal units which are applied in these positions. See CLUTCH & BAND APPLICATION
.
SHIFT SPEED SPECIFICATIONS
VEHICLE SHIFT SPEED SPECIFICATIONS (ASPIRE & FESTIVA)
VEHICLE SHIFT SPEED SPECIFICATIONS (TRACER)
ApplicationEngine RPM
Aspire2300-2500
Festiva & Tracer2300-2500
Operating Condition (1) Shift Speed MPH (km/h)
Half Throttle (50%)
1-29-17 (15-28)
2-316-34 (26-55)
Full Throttle (WOT) (2)
1-228-33 (44-53)
2-355-63 (88-101)
3-253-48 (86-78)
2-124-22 (39-35)
Coasting (2-1)9-6 (14-9)
(1)Transmission is in "D" range.
(2)To determine deceleration shift speeds, release throttle once transaxle has shifted into 3rd gear. Manually downshift shift lever
into next lower gear and record speed at which downshift occurs. Continue downshifting and recording vehicle speed until
transaxle has downshifted into low gear.
Operating Condition (1) Shift Speed MPH
Half Throttle (50%)
1-2 - Carbureted10-19
1-2 - EFI12-21
2-3 - Carbureted17-37
2-3 - EFI37-48
Full Throttle (WOT)
1-230-36
2-360-68
3-253-58
2-124-26
Fully Closed Throttle
Fro m "D" Ran ge (3 -1 )6-9
Page 8 of 26 MITCHELL 1 ARTICLE - 1988-94 AUTOMATIC TRANSMISSIONS Ford ATX Overhaul
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