A faulty cold start injector can cause several engine performance issues, especially during cold starts. Here are the most common symptoms:
- Hard Starting When Cold
- The engine takes longer to crank before starting.
- You may need to press the accelerator or attempt multiple starts.
- More pronounced in very cold weather.
- Rough Idle After Start
- The engine may run rough or feel like it’s misfiring right after starting.
- It might take a few minutes to stabilize as the engine warms up.
- Engine Stalling Right After Start
- If the cold start injector isn’t providing extra fuel, the engine may start briefly and then stall.
- The engine may need multiple restart attempts.
- Poor Fuel Economy (If Injector is Stuck Open)
- A stuck open injector will continuously spray fuel, leading to excessive fuel consumption.
- You may notice black smoke from the exhaust due to unburned fuel.
- Fuel Smell from Exhaust
- If the injector leaks fuel when it shouldn’t, you might smell raw fuel from the exhaust or engine bay.
- A leaking injector can also cause a slight fuel puddle near the intake.
- Black or Sooty Spark Plugs
- Too much fuel can foul the spark plugs, causing black, carbon-coated plugs.
- This can lead to misfires and rough engine performance.
- Check Engine Light (For Some Cars)
- Older vehicles with mechanical cold start injectors may not trigger a warning.
- In cars with ECU-controlled injectors, a diagnostic trouble code (DTC) may be stored.
How to Diagnose a Bad Cold Start Injector
- Listen for Injector Operation: Some injectors make a clicking noise when working.
- Check for Fuel Leaks: Look for leaks around the injector and fuel rail.
- Test Injector Resistance: Using a multimeter, check if the injector is within spec.
- Check Thermo-Time Switch: A faulty switch might not activate the injector.
- Manually Activate the Injector: Spraying pattern should be even, not dripping.