Hard Starting Diagnosis
The engine cranks but takes longer to start, and the condition is worsening. This typically indicates a fuel, ignition, or compression issue that is progressively failing.
Diagnosis Details
Possible Causes
Weak fuel pump or clogged fuel filter – not maintaining proper fuel pressure, especially when the engine is hot or under load.
Failing crankshaft position sensor or camshaft position sensor – intermittent signal loss delays spark or fuel timing.
Dirty or failing fuel injectors – causing lean condition or poor atomization, leading to extended cranking.
Weak battery or poor electrical connections – voltage drop during cranking affects ECU and fuel pump operation.
Failing ignition coil(s) or spark plugs – weak spark requires more cranking to ignite fuel mixture.
Vacuum leak or intake air temperature sensor issue – incorrect air-fuel mixture during cold start.
Engine mechanical issue (low compression, timing chain stretch) – rare but possible if other causes are ruled out.
Related OBD-II Codes
Not satisfied with this diagnosis?
Try Another DiagnosisWhat To Do Next
What You Should Do
Check fuel pressure at the rail (should hold pressure after key off).
Inspect fuel filter and listen for fuel pump prime.
Scan for diagnostic trouble codes (DTCs) even if check engine light is off.
Test battery voltage and clean battery terminals.
Inspect spark plugs and ignition coils.
If no codes, monitor crankshaft/camshaft sensor signals with a scope or multimeter.
Related Repairs
Share this diagnosis
Help others with similar symptoms
Disclaimer: This AI-generated diagnosis is for informational reference only. Always consult a qualified mechanic for an in-person inspection. AutOwner is not responsible for decisions made based on this information.
