P0316
Engine Misfire Detected on Startup (First 1000 Revolutions)
The misfire monitor detected misfires during the first 1000 revolutions after startup but the engine then settled. Often caused by fouled spark plugs that warm up clean, weak ignition coils, or a borderline cold-start fuel mixture.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: easy
What we see in the workshop
ON FORD ECOBOOST
Misfire detected on startup is a common EcoBoost pattern when carbon build-up is advanced, or where oil has been left too long and the VCT phasers are slow to respond on a cold start.
Symptoms
- Check engine light on or flashing
- Rough idle and uneven running
- Power loss, hesitation under acceleration
- Increased fuel consumption
- Possible smell of unburned fuel from exhaust
Common causes
Ordered by how often each turns out to be the cause.
- Spark plugs fouled when coldCommon
- Ignition coil weak below operating temperaturePossible
- Cold-start mixture too lean (fuel pressure, leaking injectors at rest)Possible
Parts involved
- Spark Plug
- Ignition Coil
- Fuel Injector
P0316 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.