05 Santa Fe 2.7 Dual Cylinder Misfire Intermittently

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Hey everyone,

I’ve been browsing this forum for a while and usually find answers by searching, but I’m stuck on an issue that started suddenly yesterday. After driving for about 15 minutes, my car reached full operating temperature. When I parked at the store, the RPMs dropped from around 1,000 to about 700, and the car started chugging.

On the way home, it was clear the engine was running on fewer cylinders than normal. I checked the OBD2 codes and got P0300, P0301, and P0304. I inspected the engine and everything looked fine. The rear catalytic converter didn’t seem unusually hot, so I ruled out a clogged exhaust system.

Today, the car was fine until I had to brake hard, and the issue happened again. After turning the car off for about 20 minutes, it was fine until I took a 90° turn, and then the problem reoccurred. The car chugs badly, lacks power, and makes a putting sound from the exhaust.

I checked the brake booster lines and other vacuum lines but didn’t find any issues. I haven’t tried using carb cleaner or brake cleaner to check for a vacuum leak yet. I’m not sure where to start, and I don’t have a proper place to work on the car.

Has anyone experienced something similar or have any suggestions?

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Diagnosing an intermittent misfire might be difficult. To identify the core problem, a methodical approach and thorough inspection are essential.

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Misfire codes (P0300, P0301, and P0304) usually point to ignition issues, like spark plugs, coils, or even a wiring problem.

Given the intermittent nature and the worsening symptoms, I’d lean towards a faulty ignition coil or a spark plug issue.

Have you considered swapping coils or plugs to see if the misfire follows? It’s a long shot without proper tools, but worth a try if you’re comfortable with it.

If that doesn’t work, a professional mechanic with diagnostic tools will be your best bet to pinpoint the problem.