Engine & Performance
Spark Plugs & Ignition Coils
Twelve plugs on an M113, two per cylinder, torqued into an aluminium head. This is not the job to hand to whoever is cheapest.
Signs you need this
- Misfire, shaking at idle, or a flashing check engine light
- Hesitation or stumble under acceleration
- Poor fuel economy with no other explanation
- Rough running that gets worse in wet weather
How we approach it
We diagnose misfires with per-cylinder misfire counters and coil primary testing rather than replacing the whole ignition system on suspicion. Plugs are always the correct heat range and electrode design for your specific engine — the wrong plug in a supercharged or turbocharged Mercedes causes misfire under boost even when everything else is perfect. Threads are cleaned and torqued to specification, and coils are seated with fresh boots and dielectric grease.
What the job includes
- 01Per-cylinder misfire counter review through Xentry
- 02Ignition coil primary and secondary resistance testing
- 03Correct-specification spark plug replacement with torque control
- 04Coil boot and connector renewal
- 05Spark plug tube seal inspection for oil contamination
- 06Adaptation reset and road test
Common questions
How often should Mercedes plugs be changed?
Most modern engines run 40,000 to 60,000 miles; supercharged and AMG engines are shorter. We check condition at every service and tell you when they are actually due rather than selling them early.
Do I need to replace all the coils if one failed?
No. We test them all and replace what has drifted out of specification. On a high-mileage car with several marginal coils we will say so, but one bad coil does not mean eight bad coils.
Let us take a look at it.
Call and describe what the car is doing. We will give you an honest assessment before any work begins.
7492 Slater Ave, Huntington Beach, CA 92647 · Mon–Fri 8:00am–5:00pm
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