P0311

Code

Generic P — Powertrain

Cylinder 11 Misfire Detected

Brand: Generic

Type: P — Powertrain

Views: UK: 30 EN: 64 RU: 48

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Page language: EN

Causes

Faulty spark plug in cylinder 11
Faulty ignition coil or coil pack for cylinder 11
Clogged or failed fuel injector for cylinder 11
Low compression or mechanical failure (valve, piston, ring) on cylinder 11
Wiring or connector fault to injector or ignition circuit for cylinder 11
Intake or vacuum leak affecting cylinder 11

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Engine runs rough, especially at idle or low load
Decreased power and acceleration
Reduced fuel economy
Strong fuel smell or increased emissions
Possible vibration or shake from engine bay

What to check

Retrieve freeze frame and live data with an OBD-II scan tool (misfire counts, PIDs)
Check for additional codes (especially related to fuel, ignition, cam/crank sensors, or evaporative system)
Visually inspect spark plug, coil/boot, and injector connector for cylinder 11
Check ignition coil primary/secondary resistance per manufacturer spec
Check fuel rail pressure and perform injector balance or pulse test
Perform a wet compression test or leak-down test on cylinder 11

Signal parameters

Misfire counter for cylinder 11 (counts/minute)
RPM and load/PIDs during misfire events
Ignition coil primary and secondary waveform for cylinder 11
Injector pulse width and injector current/waveform
Short-term and long-term fuel trims (STFT/LTFT)
Fuel rail pressure (static and under load)

Diagnostic algorithm

Connect a capable scan tool and record freeze-frame and live data while engine is idling and under load; note misfire counts and related PIDs
Visually inspect spark plug, coil, and wiring at cylinder 11; replace plug or coil if visibly damaged or out of spec
Swap the ignition coil from cylinder 11 with a known good cylinder and check if misfire follows the coil (confirms coil or harness)
Perform an injector test: listen for injector click, swap injector with another cylinder or use an injector stethoscope; monitor if misfire follows the injector
Check fuel pressure and perform an injector balance (drop) test to ensure proper fuel delivery to cylinder 11
Perform compression and/or leak-down test on cylinder 11 to identify mechanical issues
If compression and ignition/fuel check good, inspect cam/crank timing and related sensors for proper synchronization
Inspect wiring harness and repair any damaged connectors, shorts, or opens to coil/injector circuits; check resistance and continuity to PCM pins if needed
Clear codes and road-test to verify repair; if code returns, proceed with advanced scope diagnostics or consult OEM repair information

Likely causes

Worn/fouled spark plug in cylinder 11
Failed ignition coil or coil-on-plug in cylinder 11
Clogged or electrically failed fuel injector for cylinder 11
Low cylinder compression or leaking valve on cylinder 11
Damaged wiring/poor connector at injector or coil for cylinder 11

Fault status

⚠️ Status

PCM detected a misfire event on cylinder 11. Continued operation without repair can increase emissions and damage the catalytic converter. Further diagnosis required to identify the underlying cause.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5-3.0 hours