LR
All faults
EngineMedium severity

V8 misfire, rough running or poor starting in the wet

Will get worse if left.

Symptoms

Misfire under load, rough idle, hesitation, and worse running in damp weather.

Likely cause

Old HT leads, a cracked distributor cap or worn rotor arm, or fouled spark plugs.

Suggested fixes

Listed roughly in the order most owners try them.

  1. 1

    Fit new HT leads, cap and rotor

    Renew them together and route the leads so they do not touch the exhaust manifolds.

    Difficulty:
    Easy DIY
    Cost:
    £ (Under about £50 in parts)
  2. 2

    Replace the spark plugs

    Check each plug for colour. A fouled plug on one cylinder can point to a worn cam lobe or a leaking valve stem seal.

    Difficulty:
    Easy DIY
    Cost:
    £ (Under about £50 in parts)
  3. 3

    Check for vacuum leaks

    Split vacuum pipes and perished intake gaskets cause lean running and misfires.

    Difficulty:
    Moderate DIY
    Cost:
    £ (Under about £50 in parts)

This is general guidance gathered from owner experience and workshop practice, not a substitute for a workshop manual or a qualified mechanic. Costs are rough parts-only guides. Brakes, steering and suspension work affects safety, so if in doubt have it checked professionally.

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