🔧 The Symptoms
- Cylinder #4 Compression Loss: Tested at 60 PSI (Dry) and 90 PSI (Wet). Indicates a top-end leak (valve, carbon debris, or head gasket).
- Engine Rattle: Loud metallic rattling sound, potentially from a failed timing chain tensioner or a seized power steering pump.
- Stall & Smoke Event: Car ran low on oil/power steering fluid, stalled, smoked, and smelled strongly of burning rubber.
- Check Engine Light: Transitioned from a flashing light (catalyst-damaging misfire) to a solid light (hard code logged).
"The power steering fluid was low, the engine stalled... she said it was smoking and smelled like rubber, then drove it home and it's making a rattling sound."
Visual Evidence
View 1: Replaced Coils & Plugs
View 2: Potential Donor (Murano)
OBD-II Codes
| Code | Description |
|---|---|
| P0304 | Cylinder 4 Misfire Detected |
| P0300 | Random/Multiple Cylinder Misfire |
* Note: Expecting High Fuel Trim (STFT/LTFT) on Live Data due to 90 PSI compression leak.
Diagnostic Action Plan
Step 1: Ignition Refresh
Install new spark plugs and coil packs. Start engine to see if restoring combustion clears the "misfire rattle."
Step 2: The Belt Cut Test
Start engine without the power steering belt to isolate the pump. If the rattle stops, replace the pump.
Step 3: Chemtool Soak
Pour 2 oz of Berryman B-12 Chemtool into Cylinder #4 for 24 hours to dissolve carbon propping the valve open.
Step 4: Access Port Check
Inspect timing tensioner extension and plastic guides via the diamond-shaped window on the front timing cover.