1988 PONTIAC FIERO Service Repair Manual

6E2-A-54 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
465 DK GRNMlHT
450 BLWHT
FUEL PUMP BATTERY JUNCTION TEST TERM. BULKHEAD BODY CONNECTOR
BLOCK (12 VOLT) CONNECTOR
CODE 54
FUEL PUMP CIRCUIT
(LOW VOLTAGE)
5.OL (VIN E) "F"" SERIES (TBI)
Circuit Description:
When the ignition switch is turned "ON", the electronic control module (ECM) will activate the fuel pump
relay and run the in-tank fuel pump. The fuel pump will operate as long as the engine is cranking or running,
and the ECM is receiving ignition reference pulses.
If there are no reference pulses, the ECM will shut
"OFF" the fuel pump within 2 seconds after key "ON".
Should the fuel pump relay, or the
12 volt relay drive from the ECM fail, the fuel pump will be run through
an oil pressure switch back-up circuit.
Code
54 will set if the ECM does not see the 12 volts signal at terminal "B2" during the 2 seconds that the
ECM is energizing the fuel pump relay.
Diagnostic Aids:
An inoperative fuel pump relay can result in long
cranking times, particularly if the engine is cold or
engine oil pressure is low. The extended crank period
is caused by the time necessary for oil pressure to
build enough to close the oil pressure switch and turn
"ON" the fuel pump.

DRlVEABlLlTY AND EMISSIONS 5.Ob (VIN E) 6E2-A-5%
FUEL PUMP CIRCUIT
MPER WIRE, CONNECT FUEL PUMP
TO 12 VOLTS.
CONNECT TEST LIGHT BETWEEN HARNESS
CKT465 AND
EL PUMP RELAY.

6EZ-A-56 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
S.OL (VIN E) 'T" SERIES (TBI)
CODE 51
PROM ERROR
CODE 52
CALPAK ERROR
(FAULTY OR INCORRECT CALPAK)
CODE 55
ECM ERROR
CLEAR CODES AND CONFIRM "CLOSED LOOP" OPERATION AND NO "SERVICE ENGINE SOON" LIGHT.
INSTALL MISSING OR FAULTY CALPAK .
REPLACE ELECTRONIC CONTROL MODULE (ECM).

TABLE OF CONTENTS
............................................................. Before Starting Page B-1
lntermittents .............................................................. PageB-2
HardStart........,........................................................ PageB-2
...................... .................. Surges and/or Chuggle .... ........ ... Page B-3
.............................................. Lack of Power, Sluggish, or Spongy Page 8-3
DetonationISparkKnock ...................................................... PageB-4
...................................................... Hesitation,
Sag, Stumble Page B-4 8 .......................................................... Cuts Out, Misses ? .I Page 8-4
PoorFuelEconomy .......................................................... PageB-5
........................................ Rough, Unstable, or Incorrect Idle, Stalling Page
B-5
............................................. Excessive Exhaust Emissions or Odors Page
B-6
........................................................... Dieseling, Run-on Page B-6
Backfire......,..,.........,............................................... PageB-6
............................. CHART B-1, Restricted Exhaust System Check -All Engines Page B-7
BEFORE
STARTING
Before using this section you should have This check should include:
performed the DIAGNOSTIC CIRCUIT
CHECK. @ Vacuum hoses for splits, kinks, and proper
Verify the customer complaint, and locate the connections,
as shown on Emission Control
correct SYMPTOM below. Check the items Information label.
indicated under that symptom.
@ Air leaks at throttle body mounting and intake
If the ENGINE CRANKS BUT WILL NOT manifold.
RUN, see CHART
A-3. @ Ignition wires for cracking, hardness, proper
Several of the following symptom procedures routing,
and carbon tracking.
call for a careful visual (physical) check.
@ Wiring for proper connections, pinches, and cuts.
The importance of this step cannot be stressed The
following symptoms cover several engines.
too strongly
- it can lead to correcting a problem To
determine if a particular system or component is
without further checks and can save valuable time. used,
refer to the ECCM wiring diagrams for
application .

6EZ-B-2 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
Problem may or may not turn "ON" the "Service Engine Soon" light, or store a code.
DO NOT use the trouble code charts in Section
"A" for intermittent problems. The fault must be
present to locate the problem. If a fault is
intermittent, use of trouble code charts may result
in replacement of good parts.
@ Most intermittent problems are caused by faulty
electrical connections or wiring. Perform
careful check of suspect circuits for:
- Poor mating of the connector halves, or
terminals, not fully seated in the connector
body (backed out).
I - Improperly formed or damaged terminals.
All connector terminals in problem circuit
should be carefully reformed to increase
contact tension.
- Poor terminal to wire connection. This
requires removing the terminal from the
connector body to check as outlined in the
Introduction to Section
"6E".
@ If a visual (physical) check does not find the
cause of the problem, the car can be driven with
a voltmeter connected to a suspected circuit or a
"Scan" tool may be used. An abnormal voltage
reading, when the problem occurs, indicates the
problem may be in that circuit. If the wiring
and connectors check OK, and a trouble code was
stored for a circuit having a sensor, except
for Codes 44 and 45, substitute a known good
sensor and recheck.
@ Loss of trouble code memory. To check,
disconnect TPS and idle engine until "Service
Engine Soon" light comes
"ON". Code 22 should
be stored, and kept in memory, when ignition is
turned "OFF" for at least 10 seconds. If not, the
ECM
is faulty.
@ An intermittent "SES" light, and no trouble
codes, may be caused by:
- Electrical system interference caused by a
defective relay, ECM driven solenoid, or switch.
They can cause a sharp electrical surge.
Normally, the problem will occur when the
faulty component is operated.
- Improper installation of electrical options, such
as lights, 2-way radios, etc.
- EST wires should be routed away from spark
plug wires, ignition system components, and
generator. Wire for CKT 453 from ECM to
ignition system should be a good ground.
- Ignition secondary shorted to ground.
- CKTs 419 ("SES" light) or 451 (Diagnostic Test)
intermittently shorted to ground.
- ECM power grounds.
HARD START
Definition: Engine cranks OK, but does not start for a long
time. Does eventually run, or may start but immediately dies.
, <
@ CHECK: 4. Connect a radiator test pump to the line and
- For water contaminated fuel. apply 103 kPa (15 psi) pressure. If the
- Fuel system pressure CHART A-7. pressure will hold for 60 seconds, the check
- TPS for sticking or binding should read less than
valve is OK.
1.25 volts on a "Scan" tool. @ Check ignition system for:
- No crank signal; see CHART C-1B. - Proper output with ST-125.
- EGR operation; CHART C-7. - Worn shaft.
- Fuel System - CHART A-7. - Rare and shorted wires.
- For a faulty in-tank fuel pump check valve, - Pickup coil resistance and connections.
which would allow the fuel in the lines to drain
- Loose ignition coil connections.
back to the tank after the engine is stopped. To
- Moisture in distributor cap.
check for this condition:
- Spark plugs, wet plugs, cracks, wear,
1. Ignition "OFF".
improper gap, burned electrodes, or heavy
2. Disconnect fuel line at the filter
deposits.
3. Remove the tank filler cap. @ If engine starts but then, immediately stalls,
open distributor bypass line. If engine then
starts, and runs OK, replace distributor pickup
coil.
@ Check CKT 423 (EST) for short to ground.

DRIVEABILITY AND EMISSIONS 5.OL (VIN E) 6E2-B-3
SURGES AND/OR CHUGGLE
Definition: Engine power variation, under steady
throttle or cruise. Feels like the car speeds up and slows
down, with no change in the accelerator pedal.
@ Use a "Scan" tool to make sure reading of VSS
matches vehicle speedometer. See "Special
Information", Section
"6E".
e CHECK:
- For intermittent EGR at idle. See appropriate
CHART C-7.
- Ignition timing. See Emission Control
Information label.
- Inline fuel filter for dirt or restriction.
- Fuel pressure. See CHART A-7.
- Generator output voltage. Repair if less than 9,
or more than
16 volts.
- TCC Operation. CHART C-8A.
@ Inspect oxygen sensor for silicon contamination
from fuel, or use of improper RTV sealant. The
sensor may have a white, powdery
coabing and
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.
@ Remove spark plugs. Check for cracks, wear,
improper gap, burned electrodes, or heavy
deposits. Also, check condition of the rest of the
ignition system.
LACK OF BOWER, SLUGGISH, OR SPONGY
Definition: Engine delivers less than expected power. Little or no
increase in speed, when accelerator pedal is pushed down part way.
@ Compare customer's car to similar unit. Make - For restricted fuel filter, contaminated fuel or
sure the customer's car has an actual problem. improper fuel pressure. See CHART A-7.
@ Remove air cleaner and check air filter for dirt, - ECM Grounds.
or for being plugged. Replace as necessary.
- EGR operation for being open, or partly open, all
If there is spray from only one injector, then, the time
- CHART C-7.
there is a malfunction in the injector assembly,
- Generator output voltage. Repair if less than 9, or
or in the signal to the injector assembly.
'I'he more than 16 volts.
malfunction can be isolated, by switching the
- Engine valve timing and compression.
injector connectors.
If the problem remains with - Engine, for proper or worn camshaft. See Section
the original injector, after switching the
"6A".
connector, then the injector is defective. Replace - Transmission torque converter operation. See
the injector. If the problem moves with the
Sectionw7A".
injector connector, then the problem is an - Secondary ignition voltage.
improper signal in the injector circuits, see
- Proper operation or ESC. See Section "C5".
CHART A-3. @ Check exhaust system for restriction. See
@ CHECK: CHART B- 1.
- Ignition timing. See Emission Control
Information label.

6EZ-B-4 5.OL (VIN E) DRIVEABILITY AND EMISSIONS
DEWNATION 1 SPARK KNOCK
Definition: A mild to severe ping, usually worse under acceleration. The
engine makes sharp metallic knocks that change with throttle opening.
@ CHECK for obvious overheatingproblems. - For proper transmission shift points. See Section
- Low coolant. "7".
- Loose water pump belt. - TCC operation. See CHART C-8.
- Restricted air flow to radiator, or restricted - For incorrect basic engine parts such as cam,
water flow thru radiator. heads,
pistons, etc.
- Faulty or incorrect thermostat. - Excessive oil entering combustion chamber.
- Coolant sensor, which has shifted in value. @ Remove carbon with top engine cleaner. Follow
- Correct coolant solution - should be a 50150 instructions on can.
mix of GM
#lo52753 anti-freeze coolant (or @ If there is spray from only one injector, then there
equiv.) and water. is
a malfunction in the injector assembly, or in the
@ CHECK: signal to the injector assembly. The malfunction
- For poor fuel quality, proper octane rating. can be isolated by switching the injector
- For correct PROM. connectors. If the problem remains with the
- Spark plugs for correct heat range.
original injector, after switching the connector,
- ESC system opeation. See CHART C-5.
then the injector is defective. Replace the injector.
- Ignition timing. See Vehicle Emission Control
If the problem moves with the injector connector,
Information label. then the
problem is an improper signal in the
- Fuel system for low pressure. See CHART A-7.
injector circuits. See CHART A-3.
- Check EGR svstem. - CHART C-7.
HESITATION, SAG, STUMBLE
Definition: Momentary lack of response as the accelerator is pushed down.
Can occur at all car speeds.
C'sually most severe when first trying to make the car
move, as from a stop sign.
May cause the engine to stall if severe enough.
@ Perform careful visual (physical) check, as Information" label.
described at start of Section
"B". - Generator output voltage. Repair if less than 9 or
@ CHECK: more than 16 volts.
- Fuel pressure. See CHART A-7. - For open ignition system ground, CKT 453.
- Water contaminated fuel. - Canister purge system for proper operation. See
- TPS for binding or sticking.
Section "C3".
- Ignition timing. See "Emission Control - EGR valve operation, CHART C-7.
CU"F OUT, MISSES
Definition: Steady pulsation or jerking that follows engine
speed, usually more pronounced as engine load increases. The
exhaust has a steady spitting sound at idle or low speed.
@ Perform careful visual (physical) check, us
described at start of Section
"B".
@ If ignition system is suspected of causing a miss
at idle or cutting, out under load:
@ Check for missing cylinder by:
1. Disconnect IAC motor. Start engine.
Remove one spark plug wire at a time, using
insulated pliers.
2. If there is an rpm drop on all cylinders, (equal
to within 50
rpm), go to "Rough, Unstable, Or
Incorrect Idle, Or Stalling" symptom.
Reconnect
IAC motor.
3. If there is no rpm drop on one or more
cylinders, or excessive variation in drop, check
for spark, on the suspected
cylinder(s) with J
26792 (ST-1251 spark tester or equivalent. If no
spark, see Section
"6D" for "Intermittent Operation
or Miss". If there is spark, remove spark plug(s) in
these cylinders and check for:
- Cracks
- Wear
- Improper gap
- Burned electrodes
- Heavy deposits
- Perform compression check on
questionable cylinder.
@ Check wire resistance (shoulcl not exceed 30,000
ohms), also, check rotor and distributor cap.

DRIVEABILITY AND EMISSIONS 5.OL (VIN E) 6E2-B-5
@ If the previous checks did not find the problem:
- Visually inspect ignition system for moisture,
dust, cracks, burns, etc. Spray plug wires with
fine water mist to check for shorts.
- Fuel System - Plugged fuel filter, water, low
pressure. See CHART A-7.
- Perform compression check.
- Valve timing.
- Remove rocker covers. Check for bent pushrods,
worn rocker arms, broken or weak valve springs,
worn camshaft lobes. Repair as necessary. See
Section
"6A".
If there is spray from only one injector, then,
there is
a malfunction in the injector assembly,
or in the signal to the injector assembly. The
malfunction can be isolated by switching the
injector connectors. If the problem remains with
the original injector, after switching the
connector, then the injector is defective. Replace
the iniector. If the
~roblem moves with the
injector connector, then, the problem is an
improper signal in the injector circuits. See
CHART A-3.
POOR FUEL ECONOMY
Definition: Fuel economy, as measured by an actual road test, is
noticeably lower than expected. Also, economy is noticeably lower than it
was on this car at one time, as previously shown by an actual road test.
@ CHECK: @ Visually (physically) check:
- Engine thermostat for faulty part (always open) - Vacuum hoses for splits, kinks, and proper
or for wrong heat range. See Section
"6B". connections, as shown on Vehicle Emission
- Fuel Pressure. See CHART A-7. Control Information label.
@ Check owner's driving habits. - Ignition wires for cracking, hardness, and proper
- Is A/C "ON" full time (Defroster mode "ON")? connections.
- Are tires at correct pressure? e Check ignition timing. See Emission Control
- Are excessively heavy loads being carried? Information label.
- Is acceleration too much, too often? @ Remove spark plugs. Check for cracks, wear,
- Suggest driver read "Important Facts on Fuel
improper gap, burned electrodes or heavy deposits.
Economy" in owner's manual. Repair
or replace, as necessary.
@ Perform "Diagnostic Circuit Check". @ Check compression. See Section "6A".
@ Check air cleaner element (filter) for dirt or @ Check TCC for proper operation. See CHART C-8.
being plugged. Use "Scan"
tool if available.
@ Check for proper calibration of speedometer. @ Check for dragging brakes.
Suggest owner fill fuel tank and recheck fuel
economy.
@ Check for exhaust system restriction. ,
See CHART B-1.
ROUGH, UNSTABLE, OR INCORRECT IDLE, STALLING
Definition: The engine runs unevenly at idle. If bad enough, the car may
shake. Also,
the idle may vary in rpm (called "hunting"). Either condition
may be severe enough to cause stalling. Engine idles at incorrect speed.
@ CHECK: - Vacuum leaks can cause higher than normal
- Ignition timing. See Emission Control idle.
Information label.
- EGR "ONJ', while idling, will cause roughness,
- PIN switch circuit. See CHART C-1 A. stalling, and hard starting. CHART C-7.
- For injectorb) leaking. Check fuel pressure, - Battery cables and ground straps should be clean ,
CHART A-7. and secure. Erratic voltage will cause IAC to
- IAC - See CHART C-2C.
change its position, resulting in poor idle quality.
- If a sticking throttle shaft or binding linkage - IAC valve will not move, if system voltage is
causes
a high TPS voltage (open throttle
below 9, or greater than 17.8 volts.
indication), the ECM will not control idle.
- Use "Scan" tool to determine if ECM is receiving
Monitor TPS voltage. "Scan"
andlor voltmeter AlC request signal.
should read less than
1.2 volts with throttle
closed.