Spark Plug and Ignition Coil Replacement in Norwood, MA

Rough idle, a misfire or a flashing check engine light? We find the cause first.

A new spark plug next to a worn one, held in front of an engine at No Name Auto Repair in Norwood, MA
A new spark plug (left) next to a worn one (right).

What a rough idle or misfire is telling you

When your car shakes at a stop, stumbles as you pull away, or the check engine light starts flashing, one cylinder usually isn’t firing right. That’s a misfire. Worn spark plugs and failing ignition coils are common causes, but a coil boot, an injector or a vacuum leak can do the same. So we test before we replace anything.

Why Norwood drivers bring misfires to No Name

  • We test first, so we fix the cylinder that’s acting up.
  • If only one coil is bad, we tell you.
  • Free written estimate before any work.
  • Your OK before anything extra.
  • Each plug started by hand and tightened to the factory torque spec.
  • Family-owned at 64 Broadway, Norwood. 4.9 stars, 330+ Google reviews.

What we look at when your engine misfires

Worn spark plugs

As plugs wear, the gap widens and the coil works harder to fire it. You feel it as a stumble or a harder start.

Failing ignition coils

Many newer engines have a coil on each plug. When one fails, that cylinder misfires. We test the coil before we suggest replacing it.

Oil in the plug wells

Oil in plug wells, from leaking tube seals or a valve cover gasket, can bring a misfire back. We check while coils are out.

Other misfire causes

Misfires also come from fuel injectors, vacuum leaks or low compression. If it isn’t the plugs or coils, we show you what we found.

Why some engines cost more

On many 4-cylinders the plugs are easy to reach. On many V6 engines the back plugs sit under the intake, which comes off first.

Your car’s plug schedule

Your owner’s manual sets the interval. Standard plugs wear soonest. Long-life plugs usually last 60,000 to 100,000 miles, but not every iridium plug is long-life.

How we fix a misfire

  1. Read the codes

    We read the codes stored in your car’s computer. If there’s a code related to the spark plugs or ignition coils, it shows us where to look first.

  2. Inspect and test

    We pull and inspect the plug and test the coil. Oil or a burned tip can point to another problem.

  3. Written estimate first

    You get the findings and a free written estimate for your exact engine. Nothing gets replaced until you say OK.

  4. Repair and re-check

    We fit the new parts, start each plug by hand, torque it to factory spec, then clear the codes and re-check.

New spark plugs in their boxes on an engine cover in the No Name Auto Repair shop in Norwood, MA
New plugs, ready to go in.

Signs of bad spark plugs or coils

  • Shaky or rough idle at a stop
  • Stumble or hesitation when you accelerate
  • Harder starts than usual
  • Less power, or filling up more often
  • Check engine light, steady or flashing

Each of these can have other causes too, so we test first, and deeper engine problems go through engine diagnostics.

Spark plug questions

How much does spark plug replacement cost?
It depends on your engine. Plugs are easy to reach on many 4-cylinders. On many V6 engines in front-wheel-drive cars and minivans, the back plugs sit under the intake, which has to come off first, so labor varies. Call (781) 470-0707 with your year, make and model and we will tell you the price. You get a free written estimate before any work.
How often should spark plugs be changed?
Your owner’s manual sets the interval, based on the plug type your engine uses. Standard plugs wear out soonest. Many newer cars use long-life plugs that last 60,000 to 100,000 miles, but not every iridium plug is a long-life plug. We look up the factory schedule for your exact car.
What does a worn spark plug look like?
The photo at the top of this page shows a new plug next to a worn one. As a plug wears, the electrode rounds off and the gap gets wider, so the coil works harder to fire it. That can cause a misfire or a hard start. Wet, oily deposits can mean oil is getting into the cylinder. A melted tip can point to overheating. We tell you what we find on yours.
Should ignition coils be replaced with the spark plugs?
Not always. We replace a coil or boot when testing shows it has failed, or when we find a burned spark track or oil in the plug well. If only one coil is bad, we tell you. Overdue plugs make coils work harder, so changing plugs on schedule helps protect them. Anything extra waits for your OK.
Can I keep driving with a flashing check engine light?
A steady light means get it checked soon. A flashing light usually means a misfire that can overheat the catalytic converter. Keep your speed down, skip hard acceleration and heavy loads, and bring it in soon. If the car is shaking badly or losing power, pull over when it’s safe. More on the check engine light.
Will a misfire fail my Massachusetts inspection?
If your car gets the OBD emissions check (currently model year 2012 and up) and the check engine light is on, it will fail that part. We aren’t an inspection station. We find and fix what failed. Clearing the code alone won’t get you through. It resets the car’s self-checks, which need some normal driving to finish after the repair.
Is spark plug replacement part of a tune-up?
New spark plugs are usually part of a tune-up. If your car is due for a full tune-up, we can do the plugs then. If it’s misfiring or idling rough now, we start by finding the cause, which may be a plug, a coil or something else.

Car running rough? Let’s find out why.

Call (781) 470-0707 or book online. Open Mon-Sat, 8:30 AM to 6:30 PM.

Call (781) 470-0707

No Name Auto Repair & Tire Service · Family-owned · 64 Broadway, Norwood, MA 02062 Norwood · Walpole · Westwood · Canton · Dedham · Sharon · Foxborough

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