Services
Spark Plug and Ignition Lead Replacement
Ignition leads carry high-voltage energy from the distributor or coil to the spark plugs. Replacing plugs and leads to the manufacturer's specification, in the correct firing order, is essential for clean ignition.
What does Spark Plug and Ignition Lead Replacement involve at Alpay Servis?
Ignition leads carry high-voltage energy from the distributor or coil to the spark plugs. Replacing plugs and leads to the manufacturer's specification, in the correct firing order, is essential for clean ignition.
A petrol engine runs smoothly only when every cylinder receives a strong spark at exactly the right moment. The spark plug creates that spark, and the ignition leads deliver the high voltage from the distributor or coil to each plug with as little loss as possible. When either component weakens, ignition quality drops — and the engine lets you know immediately.
Why plugs and leads wear out
Plug electrodes erode microscopically with every firing; over time the gap widens and the spark weakens. Lead insulation hardens with heat, cracks, and starts leaking high voltage to ground. The result is misfiring, a shaky idle, lost power and rising fuel consumption. Unburnt fuel escaping into the exhaust also shortens the life of expensive components such as the catalytic converter.
What careful replacement involves
- Plug type and heat range are chosen according to the manufacturer's data.
- Plugs are tightened to the specified torque — neither loose nor over-tight.
- Leads are fitted one at a time so the firing order is preserved.
- Each terminal is checked for full seating and freedom from leakage.
- The engine is run to verify idle quality and pull.
Ignition problems sometimes originate outside the plugs themselves; in that case a proper diagnosis is carried out and the true cause is explained to you. If your car misfires or runs roughly, book an inspection through the online appointment form or by phone.
What Does This Service Cover?
- Inspection of plug electrodes for wear and combustion colour
- Resistance, crack and leakage checks on the ignition leads
- Selection of the correct plug type and heat range for the vehicle
- Installation of plugs at the manufacturer's torque value
- Fitting the leads in the correct firing order
- Ignition and smooth-running test after replacement
Signs You May Need This
- Shaking and uneven running at idle
- Misfiring, especially under acceleration
- Hard starting or repeated cranking
- A clear rise in fuel consumption
- Check-engine light triggered by ignition faults
Frequently Asked Questions
Should plugs and leads be replaced together?
Not always — but aged leads will limit what new plugs can deliver. If measurement or inspection shows increased resistance, cracking or leakage in the leads, replacing both is recommended. The decision is shared with you based on the actual findings.
What happens if the wrong spark plug is fitted?
A plug with the wrong heat range or gap can cause misfiring and power loss, and in the long run damage that reaches piston and valve surfaces. Plug selection is therefore always made to the values specified by the vehicle manufacturer.
What does the engine gain from new plugs?
Healthy ignition means complete combustion in each cylinder — a smooth idle, stable pull and efficient fuel use. Driving on worn plugs lets unburnt fuel escape into the catalytic converter and shortens its life.
How can I tell the leads are failing?
Cracked insulation, hardening and oxidised terminals can be seen on inspection, while increased internal resistance is found by measurement. Misfiring that gets worse in damp weather is a classic sign of voltage leaking from the leads.
Book Your Service Appointment
Choose the day and time that suit you; our team will confirm your appointment.
