Code
P3004
Generic
P — Powertrain
Cylinder 4 Misfire Detected
Views:
UK: 11
EN: 15
RU: 11
AI status
Completed
Completed
100%
Causes
- Faulty ignition coil or spark plug on cylinder 4
- Clogged, leaking, or electrically open fuel injector for cylinder 4
- Low compression (mechanical issue) in cylinder 4
- Wiring or connector fault to coil or injector
- Vacuum leak or air/fuel mixture problem affecting cylinder 4
- Low fuel pressure or weak fuel pump
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle or vibration, especially at idle
- Reduced engine power and acceleration
- Poor fuel economy and increased emissions
- Engine hesitation or stumbling under load
- Possible misfire code(s) stored and increased misfire counts in live data
What to check
- Read codes and freeze-frame / freeze data from ECM
- Scan live data: misfire counters, short-term/long-term fuel trims, O2 sensors, fuel rail pressure
- Visual inspection of spark plug, coil, injector wiring and connectors at cylinder 4
- Inspect spark plug condition and gap; measure coil and injector resistance
- Swap coil or injector with another cylinder and see if misfire follows
- Cylinder compression or leak-down test on cylinder 4 vs others
Signal parameters
- Misfire/event counters per cylinder (live data)
- Ignition coil primary/secondary waveform (oscilloscope)
- Injector pulse width and current (scan tool/oscilloscope)
- Short-term and long-term fuel trim (STFT/LTFT)
- Fuel rail pressure (static and under load)
- Crankshaft and camshaft position sensor signals
Diagnostic algorithm
- Retrieve P3004 and any other stored codes; record freeze-frame data and failure conditions (rpm, load, temp).
- Perform visual inspection: plugs, coils, wiring harness, connectors, and fuel injector connector for cylinder 4.
- Check service history for recent maintenance (plugs, coils, injectors) and known technical bulletins.
- Monitor live data while engine runs: confirm misfire counts for cylinder 4 and review fuel trims and O2 behavior.
- Swap the ignition coil from cylinder 4 with another cylinder. Clear codes and test drive. If misfire follows coil, replace coil.
- If coil swap negative, swap fuel injector with another cylinder and retest. If misfire follows injector, replace injector.
- Inspect and if necessary replace spark plug for cylinder 4; re-test.
- If ignition and injector appear good, perform static compression and/or leak-down test on cylinder 4. Repair mechanical issues as needed.
- Check fuel pressure and flow; test injector activation with scope or noid light and measure current draw.
- Inspect for intake manifold gasket leaks or vacuum leaks near cylinder 4; perform smoke test if needed.
- If timing suspicion exists, verify cam/crank correlation and timing chain/belt condition.
- After repairs, clear codes and re-evaluate on test drive and with live data to confirm misfire is resolved.
Likely causes
- Ignition coil failure at cylinder 4
- Worn or fouled spark plug in cylinder 4
- Injector stuck or not actuating for cylinder 4
- Cylinder 4 low compression due to valve, piston ring, or head gasket problem
- Open/shorted wiring or poor connector ground to coil/injector
- Localized vacuum leak or intake manifold gasket failure near cylinder 4
Fault status
Status
Stored when the ECM detects repeated misfire events on cylinder 4 over the monitoring period; MIL may be illuminated and freeze-frame data recorded.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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