Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSPONTIAC1993LEMANS FWD L4-98 1.6LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSTESTING AND INSPECTIONSYMPTOM RELATED DIAGNOSTIC PROCEDURESDIAGNOSIS BY SYMPTOMHIGH HC AT HIGH RPM
1993 Pontiac Lemans FWD L4-98 1.6L
High HC at High RPM
1993 Pontiac Lemans FWD L4-98 1.6LSECTION High HC at High RPM
This condition indicates abnormally high Hydrocarbons with low or normal CO during cruise (2500 rpm).
POSSIBLE CAUSE ACTION
Electrical misfires Check ignition system
Vacuum leak Check vacuum lines and routing.
See VACUUM AND VAPOR HOSE DIAGRAMS in EMISSIONS.
Check intake manifold, and vacuum components.
PCV malfunction Check PCV system. See POSITIVE CRANKCASE
VENTILATION in TESTING PROCEDURES.
EGR malfunction Check EGR system. See EXHAUST GAS RE-CIRCULATION
SYSTEM in TESTING PROCEDURES.
Initial timing incorrect Check Ignition Timing. See ADJUSTMENT PROCEDURES
in EMISSIONS.
Incorrect Spark Advance Check Spark Controls (EST, ESC etc..).
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.