Why is my Ford Taurus X misfiring or shaking?

Short answer: For a misfire on a Taurus X, read the code to find the cylinder, then swap that coil with another cylinder and see if the misfire follows. If it doesn't move, try the injector, then check the plug and compression. A shake only at 40-50 mph is usually tires or suspension, not the engine. A flashing check engine light means slow down and get it fixed soon.

Symptom: Rough running, a flashing or steady check engine light with a misfire code (like P0302), shaking at idle, or a shake at certain speeds.

What to check first

1. Read the code to see which cylinder is misfiring.
2. Swap that cylinder's coil with another cylinder and see if the code follows it.
3. Pull the plugs and look at them. One very black plug points to that cylinder.
4. If the misfire stays put, swap the injector or do a compression test.
5. If it only shakes at 40-50 mph, check wheel balance, tires and front-end parts.

Likely causes

1. Ignition coil. Each spark plug has its own coil. A failing coil causes a misfire on that cylinder.
2. Spark plugs. Worn plugs can cause misfires and take out coils. One owner found the misfiring cylinder's plug was black with carbon.
3. Fuel injector. A clogged or failed injector starves one cylinder. The rear three on the 3.5 V6 are under the intake manifold.
4. Low compression or valve problem. If swapping parts doesn't move the misfire, test compression.
5. Vacuum leak or worn suspension parts. A rough idle can be a vacuum leak, and a shake only at 40-50 mph points to tires, wheels or suspension instead of the engine.

What it usually costs

Owners in these threads didn't post prices.

Is it safe to keep driving?

A flashing check engine light means a misfire bad enough to overheat the catalytic converter. Drive gently and get it fixed soon. A speed-related shake from worn suspension parts should be checked before highway trips.

DIY or shop?

Coils and front plugs are DIY. The rear plugs, coils and injectors need the upper intake off, which is a bigger job. Compression testing and suspension work are often shop jobs.

Recalls, bulletins and complaints in plain words

• Recalls: NHTSA lists one recall for these years, 16V247000 (driver frontal airbag), and none for misfires. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
• NHTSA complaints: 29 keyword-matched complaints for Ford Taurus X 2008–2009 (of 164 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-30; keywords: misfire, shak, rough, coil, stall). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In 08 Taurus X 3.5L Cylinder Misfire on Car Talk, an '08 Taurus X with the 3.5 V6 had a cylinder 2 misfire code (P0302) with a flashing check engine light, and a new coil didn't fix it. Members said to swap the coil, then the injector, to another cylinder and see if the misfire moves; if it stays, check the plug and compression. They also warned a flashing light can damage the catalytic converter.
• In 2008 Ford Taurus X - Shaking and vibrating on Car Talk, a 2008 Taurus X 3.5 still shook after new plugs, coils, injectors and oxygen sensors. A member said there were really two problems: a shake at 40-50 mph points to tires, suspension or steering parts, and a rough idle in park could be a vacuum leak.

Quick tip

Don't buy parts in a pile. One swap test tells you whether it's the coil, the injector or the engine itself.

Vehicle focus: Ford Taurus X, 2008-2009, 3.5 V6.

Safety / mechanic note

Misfires and shaking can hide bigger problems. Verify with a mechanic.