1988 PONTIAC FIERO spark adjustment

F CARLINE
ITEM 10
TransmissionRransaxle Service
The manual transmission or transaxle fluid does not
require changing. (Corvette only.) Change fluid in over-
drive unit every 30,000 miles (50 000 km).
For automatic transmissions or transaxles, change
both the fluid and filter every 15,000 miles (25 000 km) if
the car is mainly driven under one or more of these
conditions:
@ In heavy city traffic where the outside temperature
regularly reaches 90°F (32°C) or higher.
@ In hilly or mountainous terrain.
@ Frequent trailer pulling.
@ Uses such as found in taxi, police car or delivery
service.
If you do not use your car under any of these condi-
tions, change both the fluid and filter every 100,000 miles
(160 000 km). See you Owner's Manual for further
details.
ITEM 11
Spark Plug Service*
Replace spark plugs with type listed in your Owner's
Manual.
ITEM 12
Spark Plug Wire Inspection*
Clean wires and inspect for burns, cracks or other dam-
age. Check the wire boot fit at distributor and at spark plugs.
Replace wires as needed.
ITEM 13
Positive Crankcase Ventilation (PCV) Valve
Inspection*
Inspect valve for proper function. Replace valve if
necessary as well as any worn, plugged or collapsed
hoses.
ITEM 14
EGR System Service*
Conduct EGR System Service as referenced in the
EGR System Chart shown in the appropriate 6E Section.
Also, refer to your GM maintenance schedule booklet for
specific applications.
ITEM 15
Air Cleaner and PCV Filter Replacement*
On 1.6 and 2.0 liter engines, replace every 50,000
miles (80 000 km). On all other engines, replace every
30,000 miles (50 000 km). Replace more often under
dusty conditions. Ask your dealer for the proper replace-
ment interval for your driving conditions.
MAINTENANCE AND LUBRICATION 08-3
ITEM 16
Engine Timing Check*
Adjust timing to underhood label specifications. If
no specifications are shown, no adjustment is needed.
ITEM 17
Fuel Tank, Cap and Lines Inspection*
Inspect fuel tank, cap and lines (including fuel rails
and injection assembly, if so equipped) for damage or
leaks. Inspect fuel cap gasket for an even filler neck
imprint or any damage. Replace parts as needed.
ITEM 18
Thermostatically Controlled Air Cleaner
Inspection*
If your car is equipped, inspect all hoses and ducts
for proper hookup. Make sure valve works properly.
OWNER INSPECTIONS AND SERVICES
Listed below are inspections and services which
should be made by either you or a qualified technician at
the intervals shown to help ensure proper safety, emission
performance and dependability of your car. Take any
problems promptly to your dealer or another qualified
technician for service advice. Whenever repairs are neces-
sary, have them completed at once. For your safety and
that of others, any safety-related parts that could have
been damaged in an accident should be inspected and all
needed repairs should be done before operating your car.
Be sure to use the proper fluids and lubricants as shown in
Figure OB-2.
WHILE OPERATING YOUR VEHICLE
Automatic transmissionltransaxle shift indi-
cator operation - Make sure the indicator points to the
gear chosen.
Horn operation - Blow the horn occasionally to
make sure it works. Check all button locations.
I
Brake system operation -- Be alert to abnormal
sounds, increased brake pedal travel or repeated pulling to
one side when braking. Also, if a brake warning light
comes on or flashes, or the anti-lock warning light (if
equipped) comes on or remains on, something may be
wrong with part of the brake system. Have it inspected and
repaired at once.
Exhaust system operation - Be alert to any
changes in the sound of the system or any smell of fumes.
These are signs the system may be leaking or overheating.
.
Have it inspected and repaired at once. Also see "Engine
Exhaust Gas Caution (Carbon Monoxide)" and "Catalytic
Converter" in your Owner's Manual.
*An Emission Control Service

ENGINE GENERAL INFORMATION 6-1
SECTION 6
NE GENERAL NFORMAT
Description ............................................................... 6 TBI ...................................... .. ...... 6E2 ................ Engine Mechanical Multi Port Fuel Injection (MPFI) 6E3 -
............................................... 2.8L V-6 ....................................................... 6A2 Exhaust Systems 6F
5.OL V-8 ......................................................... 6A3 ~~~~~~l ~~f~~~~ti~~ ..................................... 6-2
............................ Engine Cooling ...................................................... 6B Engine Performance Diagnosis 6-3 ............................. Engine Fuel 6C Engine Mechanical Diagnosis
6-3 ........................................................... ................................... Engine Knock Diagnosis 6-4
Engine Electrical ................................................... 6D Compression Test ...................................... ... 6-5
................... Driveability and Emission Controls ...................... 6E Oil Leak Detection .. ..................... 6-5
ALL NEW GENERAL MOTORS VEHICLES ARE CERTIFIED BY THE UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY AS CONFORMING TO THE REQUIREMENTS OF
THE REGULATIONS FOR THE CONTROL OF AIR POLLUTION FROM NEW MOTOR VEHICLES.
THlS CERTIFICATION IS CONTINGENT ON CERTAIN ADJUSTMENTS BEING SET TO
FACTORY STANDARDS. IN MOST CASES, THESE ADJUSTMENT POINTS EITHER HAVE
BEEN PERMANENTLY SEALED AND/OR MADE INACCESSIBLE TO PREVENT
INDISCRIMINATE OR ROUTINE ADJUSTMENT IN THE FIELD. FOR
THlS REASON, THE
FACTORY PROCEDURE FOR TEMPORARILY REMOVING PLUGS, CAPS, ETC., FOR
PURPOSES OF SERVICING THE PRODUCT MUST BE STRICTLY FOLLOWED AND,
WHEREVER PRACTICABLE, RETURNED TO THE ORIGINAL INTENT OF THE DESIGN.
DESCRIPTION OF: SECTION 6
SECTION 6A - ENGINE MECHANICAL used for each carburetor. TBI units are described in
This section general contains information on the Section 6E.
mechanical parts of the engine, such as block,
crankshaft, pistons, valve train, and camshaft, that are
common to most engines. Overhaul procedures,
removal and replacement procedures, and
s~ecifications are also covered. Subsections furnish
detailed information on each specific engine. Service
SECTION 6D - ENG l N E ELECTRICAL
information is also given that relates to that engine's
use in each
Carline. Specific subsections are: Items
covered in this section are battery,
generator, starter, primary and secondary ignition,
6A2
- 2.8L V-6 Engine
engine wire harness, spark plugs and wires, and
6A3
- 5.OL V-8 Engine
ignition switch.
SECTION 6B - ENGINE COOLING
Engine cooling system components such as
radiator, water pump, thermostat, and cooling fan, are
covered in this section. Accessory drive belts are also
covered, along with cooling system capacities.
SECTION 6C - FUEL SYSTEM
This section contains information on all the parts
of the fuel system
except the carburetor, or Throttle
Body Injection unit (TBI) itself. Items covered are fuel
tank, fuel pump, and fuel lines. Specific subsections are
SECTION 6E - DRIVEABILITY AND EMISSIONS
This section covers emission control systems
general information, and diagnostic procedures which
will lead to repairing performance and driveability
related problems for gasoline engine equipped vehicles.
All emission components are covered, as well as all
removal and replacement procedures. Instructions on
use of special tools are also given. Specific sections are:
6E
- Driveability and Emissions
6E2
- Fuel Injection (TBI)

V-8 ENGINE 6A3-9
surfaces of rocker arms and rocker arm balls
with "Molykote" or its equivalent.
1. Install push rods.
Be sure push rods seat in lifter
socket.
2. Install
rocker arms, rocker arm balls and rocker
arm nuts. Tighten rocker arm nuts until all lash
is eliminated.
3. Adjust
valves when lifter is on base circle of
camshaft lobe as follows:
a. Crank engine until mark on torsional
damper lines up with center or
"0" mark on
the timing tab fastened to the crankcase
front cover and the engine is in the
#l
firing position. This may be determined by
placing fingers on the
# 1 valve as the mark
on the damper comes near the
"0" mark on
the crankcase front cover. If the valves are
not moving, the engine is in the
# 1 firing
position. If the valves move as the mark
comes up to the timing tab, the engine is in
#6 firing position and should be turned
over one more time to reach the
#1
position.
b. With
the engine in the
# 1 firing position as
just determined, the following valves may be
adjusted:
e Exhaust--1, 3, 4, 8
e Intake--1, 2, 5, 7
, ,
Fig. 6A3-8 Valve Adjustment - Typical
c. Back out adjusting nut until lash is felt at
the push rod then turn in adjusting nut until
all lash is removed. This can be determined
by rotating push rod while turning adjusting
nut (fig.
6A3-8). When play has been
removed, turn adjusting nut
1 + 1/4 in
additional turn (to center lifter plunger).
d. Crank
the engine one revolution until the
pointer
"0" mark and torsional damper
mark are again in alignment. This is
#6
firing position. With the engine in this
position the following valves may be
adjusted.
e Exhaust--2, 5, 6, 7
o ntake--3, 4, 6, 8
4. Install rocker arm covers as previously outlined.
5. Start engine and adjust carburetor idle speed, if
needed.
VALVE STEM OIL SEAL AND/OR VAL\/E
SPRING (6A3-9)
INTAKE VALVE DETAIL
EXHAUST VALVE DETAIL
Fig. 6A3-9 Valve Seals
Fig.
6A3-10 Compressing Valve Spring
Removal
1. Remove rocker arm cover as previously outlined.
2. Remove
spark plug, rocker arm and push rod on
the
cylinder(s) to be serviced.
3. Install air line adapter Tool J-23590 to spark plug
port and apply compressed air to hold the valves
in place.
4. Using Tool J-5892 to compress the valve spring,
remove the valve locks, valve cap and valve
spring and damper (fig.
6A3-10).
5. Remove
the valve stem or head oil seal.

QA3-10 V-8 ENGINE
lnstallation
1. Install valve stem seal over valve stem and seat
against head.
2. Set
the valve spring and damper, oil shedder and
valve cap in place. Compress the spring with Tool
J-5892 and install oil seal in the lower groove of
the stem, making sure the seal is flat and not
twisted. A light coat of oil on the seal will help
prevent twisting.
3. Install
the valve locks and release the compressor
tool making sure the locks seat properly in the
upper groove of the valve stem. Grease may be
used to hold the locks in place while releasing the
compressor tool.
4. Using tool J-23994, apply vacuum to the valve
cap to make sure no air leaks past the seal.
5. Install spark plug and torque to 22 lb. ft.
(30N.m).
6. Install and adjust valve mechanism as previously
outlined.
VALVE LIFTERS
Hydraulic valve lifters very seldom require
attention. The lifters are extremely simple in design,
readjustments are not necessary, and servicing of the
lifters requires only that care and cleanliness be
exercised in the handling of parts.
Valve Lifter Diagnosis
1.
Momentarily Noisy When Car is Started:
This condition is normal. Oil drains from the
lifters which are holding the valves open when the
engine is not running. It will take a few seconds
for the lifter to fill after the engine is started.
2. Intermittently Noisy On Idle Only. Disappearing
When Engine Speed is Increased:
Intermittent clicking may be an indication of a
pitted check valve ball, or it may be caused by
dirt.
Correction: Clean the lifter and inspect. If check
valve ball is defective, replace lifter.
3. Noisy At Slow Idle Or With Hot Oil, Quiet With
Cold Oil Or As Engine Speed Is Increased:
High leak down rate. Replace suspect lifter.
4. Noisy At High Car Speeds And Quiet At Low
Speeds:
a. High oil level
- Oil level above the "Full"
mark allows crankshaft counterweights to
churn the oil into foam. When foam is
pumped into the lifters, they will become
noisy since a solid column of oil is required
for proper operation. Correction: Drain oil
inti1 proper level is obtained.
b. Low oil level - Oil level below the "Add"
mark allows the pump to pump air at high
speeds which results in noisy lifters.
Correction: Fill until proper oil level is
obtained.
c. Oil pan bent on bottom or pump screen
cocked or loose, replace or repair as
necessary. 5.
Noisy At Idle Becoming Louder As Engine Speed
Is Increased To 1500 rpm:
This noise is not connected with lifter
malfunction. It becomes most noticeable in the
car at 10 to 15 mph "1" (Low) range, or 30 to
35
mph "DM (Drive) range and is best described as
a
hashy sound. At slow idle, it may be entirely
gone or appear as a light ticking noise in one or
more valves. It is caused by one or more of the
following:
a. Badly worn or scuffed valve tip and rocker
arm pad.
b. Excessive valve stem to guide clearance.
c. Excessive valve seat
runout.
d. Off square valve spring.
e. Excessive valve face
runout.
f. Valve spring damper clicking on rotator.
Removal
1.
Remove intake manifold as previously outlined.
2. Remove valve mechanism as previously outlined.
3. Remove valve lifter retainer.
4. Remvoe valve lifter restrictor.
5. Remove valve lifters (Fig.
6A3-7). Place valve
lifters in a rack so that they may be reinstalled in
the same location.
Installation
1.
Coat roller of valve lifters with "Molykote" or its
equivalent and install valve lifters.
2. Install valve lifter restrictor.
3. Install valve lifter retainer.
4. Install intake manifold as previously outlined.
5. Install and adjust valve mechanism as outlined.
Disassembly
PLUNGER SPRING
Fig. 6A3-1 1 Hydraulic Valve Lifter
1. Hold the plunger down with a push rod, and
using the blade of a small screw driver, remove
the push rod seat retainer.
2. Remove the push rod seat and metering valve
(fig.
6A3- 1 1).

ENGINE FUEL BC-1
SECTION 6C
NE FUEL
CONTENTS
General Description ..................................... 6C-1 Fuel
Cap ........................................................... 6C-3
.................................................. ............................................. Alcohol-In-Fuel 6C- 1 Fuel Filter Neck 6C-3
................... ............ Fuel Metering .................................................. 6C-2 Fuel Gage Sending Unit .. 6C-4
....................... ............................... Throttle Body Injection (TBI) .... 6C-2 Diagnosis ,. 6C-4 ................... Service
Procedures ............................................. 6C-4
Port Fuel Injection ...................................... 6C-2
Pressure Relief ........................................... 6C-4
Fuel Feed and Return Pipe
............................... 6C-2
Flow Test .................................................... 6C-4
Fuel Pipes (MPFI)
.......................................... 6C-3
Pressure Test - TBI ................................... 6C-4
Fuel and Vapor Hoses
....................................... 6C-3
Pressure Test - MPFI .................................... 6C-4
Fuel Pump ........................................................ 6C-3 ...................................................... Fuel Pump Relay .............................................. 6C-3 Fuel Tank 6C-4
Fuel Filter
......................................................... 6C-3 Accelerator Controls ...................................... 6C-5
Fuel Tank
....................................................... 6C-3
All new General Motors vehicles are certified by
the United States Environmental Protection Agency as
conforming to the requirements of the regulations for
the control of air pollution from new motor vehicles.
This certification is contingent on certain adjustments
being set to factory standards. In most cases, these
adjustment points either have been permanently
sealed and/or made inaccessible to prevent
indiscriminate or routine adjustment in the field. For
this reason, the factory procedure for temporarily
removing plugs, caps, etc., for purposes of servicing the
product must be strictly followed and, wherever
practicable, returned to the original intent of the
design.
GENERAL DESCRIPTION
All gasoline engines are designed to use only
unleaded gasoline. Unleaded gasoline must be used for
proper emission control system operation. Its use will
also minimize spark plug fouling and extend engine oil
life. Using leaded gasoline can damage the emission
control system and could result in loss of emission
warranty coverage.
All cars are equipped with an Evaporative
Emission System. The purpose of the system is to
minimize the escape of fuel vapors to the atmosphere.
Information on this system will be found in Section
6E2, or 6E3.
When working on the fuel system, there are
several things to keep in mind.
@ Any time fuel system is being worked on,
disconnect the negative battery cable
except for those tests where battery
Adhere to all Notices and Cautions.
Always keep a dry chemical (Class B) fire
extinguisher near the work area.
-
Always use a backup wrench when loosening or
tightening a screw couple fitting.
The torque on a screw fitting is
30 N-m (22 lb.
ft.).
Pipe is used on all MPFI, TPI, SFI, and TBI
applications. Fittings require the use of an
"0"
Ring. Replace all pipe with the same type of pipe
and fittings that were removed.
All fuel pipes must meet GM Specification
124-M, or its equivalent.
All fuel hoses must meet GM Specification
6163-M, or its equivalent.
Do not replace fuel pipe with fuel hose.
voltage is required.
@ On MPFI, TPI, SF1 and TBI systems, always A1cohol-ln-Fuel
relieve the line pressure before servicing any fuel Certain driveability complaints such as
system components. hesitation, lack of power, stall, no start, etc., may be
@ Do not repair the fuel system until you have read caused
by an excessive amount of alcohol-in-fuel. The
the copy and checked the illustrations relating to complaints
may be due to fuel system corrosion and
that repair. subsequent
fuel filter plugging, deterioration of rubber

IGNITION SYSTEM 6B4-3
flash-over, which causes engine misfiring. Do not
mistake corona discharge for flash-over, or a shorted
insulator. Corona is a steady blue light appearing
around the insulator, just above the shell crimp. It is
the visible evidence of a high-tension field and has no
effect on ignition performance. Usually it can be
detected only in darkness. This discharge may repel
dust particles, leaving a clear ring on the insulator just
above the shell. This ring is sometimes mistakenly
regarded as evidence that combustion gases have blown
out between shell and insulator.
lgnition Switch
The mechanical switch is located in the steering
column on the right hand side just below the steering
wheel. The electrical switching portion of the assembly
is separate from the key and lock cylinder. However,
both are synchronized and work in conjunction with
each other through the action of the actuator rod
assembly.
For a complete explanation of the key and lock
cylinder, and the actuator rod assembly, see
STEERING, Section
38. See Section 8 for electrical
switching.
DIAGNOSIS
IGNITION SYSTEM
Spark Plugs
Worn or dirty plugs may give satisfactory
operation at idling speed, but at higher RPM they
frequently fail. Faulty plugs are indicated in a number
of ways: poor fuel economy, power loss, loss of speed,
hard starting and generally poor engine performance.
Spark plugs may also fail due to carbon fouling,
excessive gap, or a broken insulator. Fouled plugs may
be indicated by black carbon
deposits. The black deposits are usually the result of
slow-speed driving and short runs, where sufficient
engine operating temperature is seldom reached. Worn
pistons, rings, faulty ignition, over-rich carburetion
and spark plugs which are too cold will also result in
carbon deposits.
Excessive gap wear, on plugs of low mileage,
usually indicates the engine is operating at high speeds,
or loads that are consistently greater than normal, or
that a plug which is too hot is being used. Electrode
wear may also be the result of plug overheating,
causcd
by combustion gases leaking past the threads due to
insufficient torquing of the spark plug. Excessively lean
carburetion will also result in accelerated electrode
wear.
Broken insulators are usually the result of
improper installation, or carelessness when regapping
the plug. Broken upper insulators usually result from
a poor fitting wrench, or an outside blow. The cracked
insulator may not show up right away, but will as soon
as oil or moisture penetrates the crack. The crack is
usually just below the crimped part of shell and may
not be visible.
Broken lower insulators usually result from
carelessness when regapping and generally are visible.
This type of break may result from the plug operating
too "hot", which may happen in periods of high-speed
operation or under heavy loads. When regapping a
spark plug, always make the gap adjustment by
bending the ground (side) electrode. Spark plugs with
broken insulators should always be replaced.
HE1 Distributor
See Unit Repair for distributor disassembly, test
and reassembly of individual distributor components,
when the distributor is removed from the vehicle. See
On-Car Service for distributor removal and installation
and for component removal with distributor in car. See
Section 6E for
HE1 and EST diagnosis.
SERVICE PROCEDURES
IGNITION SYSTEM
Distributor Ignition
NOTICE: This procedure is generally true for
most carlines. Where procedure is different, or
where additional information is required, see
"ON-CAR SERVICE" for specific
carline.
HE1 DISTRIBUTOR
Service Precautions
1. When making compression checks, disconnect
the ignition switch feed wire at the distributor.
When disconnecting this connector,
do not use
a screwdriver or tool to release the locking tab, as
it may break.
2. No periodic lubrication is required. Engine oil
lubricates the lower bushing and an oil-filled
reservoir provides lubrication for the upper
bushing. 3.
The tachometer (TACH) terminal is next to the
ignition switch (BAT) connector on the
distributor cap.
NOTICE: The tachometer terminal must
NEVER be allowed to touch ground, as damage
to the module and/or ignition coil can result.
Some tachometers currently in use may NOT be
compatible with the High Energy Ignition System.
Consult the manufacturer of the tachometer if
questions arise.
4. Dwell adjustment is controlled by the module,
and cannot be adjusted.
5. The material used to construct the spark plug
cables is very soft. This cable will withstand more
heat and carry a higher voltage, but scuffing and
cutting become easier. The spark plug cables
must be routed correctly to prevent
chafing or
cutting. See Spark Plug Section. When removing

6E2-8-6 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
- MAP Sensor - Ignition "ON", engine stopped.
Compare MAP voltage with known good vehicle.
-
Voltage should be the same + 400 mV (.4 volts).
OR
Start and idle engine. Disconnect
sensor
electrical connector. If idle improves, substitute
a known good sensor and recheck.
- A/C refrigerant pressure too high. Check for
overcharge or faulty pressure switch.
- PCV valve for proper operation by placing finger
over inlet hole in valve end several times. Valve
should snap back. If not, replace valve.
Run a cylinder compression check See Section
" 6".
Inspect oxygen sensor for silicon contamination
from fuel, or use of improper RTV sealant. The
sensor will have a white, powdery coating, and
will result in a high but false signal voltage (rich
exhaust indication). The ECM will then reduce
the amount of fuel delivered to the engine,
causing a severe driveability problem.
EXCESSIVE EXHAUST EMISSIONS OR ODORS
Definition: Vehicle fails an emission test. Vehicle has excessive "rotten egg"
smell. Excessive odors do not necessarily indicate excessive emissions.
@ Perform "Diagnostic Circuit Check".
@ IF TEST SHOWS EXCESSIVE CO AND HC, (or
also has excessive odors)
@ Check items that will cause engine to run
RICH.
e Make sure engine is at normal operating
temperature.
o CHECK:
- Fuel pressure. See CHART A-7.
- Incorrect timing. See Vehicle Emission
Control Information label.
- Canister for fuel loading. See CHART C-3.
- PCV valve for being plugged, stuck or blocked
PCV hose or fuel in the crankcase.
- Spark plugs, plug wires, and ignition
components. See Section
"6D".
- Check for lead contamination of catalytic
converter (look for removal of fuel filler neck
restrictor).
- Check for properly installed fuel cap.
@ If the system is running rich, (block learn less
than
1181, refer to "Diagnostic Aids" on facing
page of Code
45.
o IF TEST SHOWS EXCESSIVE NOx:
@ Check items which cause car to run LEAN, or
to run too hot.
- EGR valve for not opening. See CHART C-7.
- Vacuum leaks. - Coolant system and coolant fan for proper
operation. See
CHART C-12.
- Remove carbon with top engine cleaner.
Follow instructions on can.
- Check ignition timing for excessive base
advance. See Emission Control Information
label.
@ If the system is running lean, (block learn greater
than
138) refer to "Diagnostic Aids" on facing
page of Code
44.
DIESELING, RUN-ON
Definition: Engine continues to run after key is turned "OFF", but runs very roughly.
Ifengine runs smoothly, check ignition switch and adjustment.
@ Check injector for leaking. Apply 12 volts to fuel Visually check injector and TBI assembly for fuel
pump test terminal to turn "ON" fuel pump and leakage.
pressurize fuel system.
BACKFIRE
Definition: Fuel ignites in intake manifold, making a loud popping noise.
@ CHECK: - For faulty spark plugs and/or plug wires or
- EGR operation for being open all the time. See
hoots.
CHART C-7. - Faulty A.I.R. check valve.
- Output voltage of ignition coil. @ Perform a compression check - look for sticking or
- For crossfire between spark plugs (distributor leaking valves.
cap, spark plug wires, and proper routing' of plug
- For proper valve timing.
wires).
- Broken or worn valve train parts.
- Engine timing - See Emission Control
Information label.

6EZ-C1-4 S.OL (VIN E) DRIVEABILITY AND EMISSIONS
THROTTLE VALVE
ENGINE CONTROL MODULE (ECM)
THROTTLE POSITION
(TPS)
8P 0321.
Figure C1-7 - Throttle Position Sensor (Typical)
A brolten or loose TPS can cause intermittent bursts of
fuel from the injector, and an unstable idle, because
the ECM thinks the throttle is moving. Once a trouble
code is set, the ECM will use an artificial value for
TPS, and some vehicle performance will return.
On all engines, the TPS is not adjustable. The
ECM uses the reading at idle for the zero reading, so
no adjustment is necessary.
Knock Sensor
The knock sensor is mounted in the engine block.
When abnormal engine vibrations (spark knock) are
present, the sensor produces a voltage signal, which is
sent to the ESC module.
See Section
"C5" for further information on the
electornic spark control
(ESC) system.
ParklNeutral Switch (Auto Only)
The parWneutra1 (PIN) switch indicates to the
ECM when the transmission is in park or neutral.
This information is used for the TCC
, and the IAC
valve operation.
Important
Vehicle should not be driven with parklneutral
switch disconnected as idle quality will be affected
and a possible false Code
24 VSS.
See Section
"8A" for more information on the PIN
switch, which is part of the neutrallstart and
backup light switch assembly.
Crank Signal
The ECM looks at the starter solenoid to tell when
the engine is cranking. It uses this to tell when the car
is in the Starting Mode.
If this signal is not available, car may be hard to
start in extremely cold weather.
AIC Request Signal
This signal tells the ECM that the AJC selector
switch is turned
"ON", and that the pressure cycling
switch is closed. The ECM uses this to adjust the idle
speed when the air conditioning is working.
Vehicle Speed Sensor (VSS)
The vehicle speed sensor (VSS) sends a pulsing
voltage signal to the ECM, which the ECM converts to
miles per hour. This sensor mainly controls the
operation of the TCC system. See "TCC System" for
more information.
Distributor Reference Signal
The distributor sends a signal to the ECM to tell it
both engine rpm and crankshaft position. See "EST
System" for further information.
Power Steering Pressure Switch (PSPS)
I
This switch tells the ECM that the vehicle is in a
parking maneuver.
The ECM uses this information to
compensate for the additional engine load by moving
the IAC valve. The ECM will, also, turn
"OFF" the
A/C clutch when high pressure is detected.
( POWER STEERING PRESSURE SWITCH
Figure C'I-8 - Power Steering Pressure Switch (PSPS)