Pontiac Fiero 1988 Service Manual page 515

6E2-B-6 DRIVEABILITY AND EMISSIONS - FUEL INJECTION (TBI)
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,
for also has excessive odors):
9 Check items which cause car to run RICH.
• Make sure engine Is at normal
operating temperature.
• 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 118), refer to "Diagnostic Aids" on
facing page of Code 45.
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.
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. If engine runs
smoothly, check ignition switch and adjustment.
* Check injector for leaking. Apply 12 volts to fuel Visually check injector and TBI assembly for
pump test terminal to turn on fuel pump and fuel leakage,
pressurize fuel system.
BACKFIRE
Definition: Fuel ignites in intake manifold, or
in exhaust system, making a loud popping noise.
CHECK:
EGR operation for being open all the time. See
CHART C-7.
Output voltage of ignition coil(s).
For crossfire between spark plugs (ignition coils,
spark plug wires, and proper routing of plug
wires).
For faulty spark plugs and/or plug wires or
boots.
Perform a compression check - look for sticking
or leaking valves.
For proper valve timing.
Broken or worn valve train parts.