The PCV (crankcase breather) on the EA888 has a diaphragm that fails, and it sits behind a whole cluster of common symptoms. The valve regulates crankcase pressure; when the diaphragm splits it creates a vacuum leak and passes excess oil vapour.
Symptoms:
- Rough idle, hunting, or stalling.
- A whistle or hiss from the top of the engine — the tell-tale.
- Lean codes (P0171), misfires.
- Raised oil consumption and faster carbon build-up.
The fix:
- Replace the PCV / breather valve — an updated design supersedes the early one on most engines. It's a bolt-on on top of the engine.
- Confirm the fix with a smoke test or by watching the symptoms clear.
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