When your 2022 Toyota 4Runner runs rough after water entered the air intake during off-roading or water crossing, the engine may have ingested water. The severity ranges from minor (wet air filter only) to major (internal engine damage), and proper assessment is critical before continuing to drive.
Assessing Water Ingestion Severity
Check the air filter first - if it's soaked, water reached the intake. If the filter is only damp around edges, minimal water entered. A completely saturated filter means significant water reached the intake, and some may have entered the engine.
Why the Engine Runs Rough
Water in the combustion chamber affects ignition - spark plugs can't ignite a water-rich mixture properly. Water on sensors provides incorrect readings, causing wrong fuel calculations. If water reached the catalytic converter, it can cause temporary efficiency problems. All these create rough running conditions.
Immediate Steps
Don't continue driving with rough running after water exposure - this masks the severity. Check engine oil for a milky appearance indicating water contamination. Remove and inspect spark plugs for water presence. Replace the air filter before any further driving attempts.
Recovery Process
If water didn't reach cylinders (dry filter interior), replace the filter and the rough running should clear quickly. If water entered cylinders, remove plugs, crank to expel water, change oil, replace plugs, and monitor for persistent issues. Compression test confirms if mechanical damage occurred.