When your 2022 Toyota Highlander sputters during startup - making uneven, irregular sounds before settling into smooth operation - the engine is struggling momentarily to achieve stable combustion. This brief sputtering may be normal or indicate developing issues.
Cold Start Enrichment
Engines use extra fuel during cold starts to compensate for poor fuel vaporization in cold conditions. If enrichment is incorrect - too little fuel or fuel delivery issues - the engine sputters before the computer compensates. This is more pronounced in cold weather.
Fuel System Considerations
Sputtering at startup can indicate fuel delivery issues: weak fuel pump not building pressure quickly enough, fuel injectors with deposit buildup affecting spray patterns, or low fuel pressure from a failing regulator. These cause uneven combustion during the demanding startup phase.
Spark Plug Condition
Worn or fouled spark plugs may fire inconsistently during cold start when demands on the ignition system are highest. As the engine warms and conditions improve, weaker plugs may perform adequately, making the problem seem startup-specific.
Direct Injection Factors
The Highlander's direct injection engine can develop carbon buildup on intake valves, affecting airflow and combustion during cold starts. Carbon deposits are more problematic when cold and may cause sputtering that diminishes as the engine warms.
Air Intake Issues
A restricted air filter or intake leak can affect the air-fuel mixture during startup. The computer's startup calibration assumes normal air flow - deviations cause temporary sputtering until the adaptive systems compensate.
When to Be Concerned
Brief sputtering (1-2 seconds) that immediately resolves may be acceptable cold-start behavior. Extended sputtering, sputtering on warm restarts, rough running that persists, or check engine light illumination indicates problems needing diagnosis.