Pontiac Fiero 1988 Service Manual page 643

6E3-B-4 DRIVEABILITY AND EMISSIONS - FUEL INJECTION (PORT)
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.
• If a "Scan" tool is available which plugs in to the
assembly line data link (ALDL) connector,
make sure reading of vehicle speed sensor (VSS)
matches vehicle speedometer. See Introduction
explaining "Scan" tool positions.
• Be sure driver understands Transmission
Converter Clutch and A/C compressor operation
in Owner's Manual.
• Perform careful visual inspection as described
at start of Section "B".
• CHECK:
Generator output voltage. Repair if less
than 9 or more than 16 volts.
Exhaust gas recirculation (EGR) - There
should be no EGR at idle. See CHART C-7.
EGR filter for being plugged.
Vacuum lines for kinks or leaks.
Ignition timing. See Emission Control
Information label.
In-line fuel filter. Replace if dirty or
plugged.
Fuel pressure while condition exists. See
CHART A-7.
® Inspect Oxygen sensor for silicon contamination
from fuel, or use of improper RTV sealant. The
sensor may have a white, powdery coating and
result in a high but false signal voltage (rich
exhaust indication). The electronic control
module (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 distributor cap,
rotor, and spark plug wires.
LACK OF POWER, SLUGGISH, OR SPONGY
Definition: Engine delivers less than expected power. Little or no
increase in speed when accelerator pedal is pushed down part way.
• Perform careful visual check as described at
start of Section "B".
• Compare customer's car to similar unit.
Make sure the customer's car has an actual
problem.
• Remove air cleaner and check air filter for
dirt, or for being plugged. Replace as
necessary.
• CHECK:
Ignition timing. See Emission Control
Information label.
Restricted fuel filter, contaminated fuel
or improper fuel pressure. See CHART A-
7.
ECM power grounds - See wiring
diagrams.
EGR operation for being open or partly open
all the time - CHART C-7.
Exhaust system for possible restriction. See
CHART B-1.
Generator output voltage. Repair if less
than 9 or more than 16 volts.
Engine valve timing and compression.
Engine for proper or worn camshaft. See
Section "6A".
Secondary voltage using a shop ocilliscope
or a spark tester J-26792 (ST-125) or
equivalent.