I have a 2006 Accord V6 with 126K Miles. I'm experiencing a rough idle at stop and the check engine light is on. I had the car scanned for codes, and three came up.

　
　
1. P0304 - Cylinder 4 Misfire Detected

2. 65-1 - Brake Fluid Low Level

3. 61-1 - Battery Voltage Malfunction

　
　
All 6 spark plugs were replaced at 74K miles. How would I know if it's the plug for Cylinder 4 or the coil? Could it be valves? I do hear a ticking noise. I added more brake fluid, and the same code appears. I also had them check the battery and charging system and all seems to be ok.

　
　
Do you know could be the problem?


Thanks

 

Swap the coils between cylinder 4 and another cylinder. See if the misfire moves from cylinder 4 to the other cylinder.

 

I'll try that, thanks. However, last night I unplugged the wire to cylinder 4 coil and notice the engine shakes slightly. I then unplugged another cylinder coil and the engine shakes much more. Could this be that i have a bad coil or a bad spark plug?

 

If it didn't change when you replaced the plugs, then I'd look at the coils. Swapping the coils & watching whether the misfire moves to a new cylinder seems like the best next test.

 

I'll replace all the plugs and see what happens. Would you happen to know the best plugs I should use? I would like to order from the internet, if possible.

Thank you.

 

I get NGK's from Rock Auto.I'd also look at replacing the cap and rotor while I'm in there. It's cheap insurance.
I prefer to do a full tune up though. Cap, rotor, plugs and wires. The owner's manual calls this out. I do this espescially if I dont know when it was last done.

 

I'll get the NGK laser Iridium's. Also, this is a 2006 Accord V6, no cap and rotor. It has coil packs for each cylinder. Should i replace all the coil packs when replacing the spark plugs? If so, should i go dealer or aftermarket on the coil packs?

Thank you.

 

Generally don't replace the coils "just because". When you replace the plugs, look at them for any visible problems.

I think if new plugs don't fix it, then look at the coils. If the misfire follows the coil to a new cylinder, then replace that one.

 

Thank you! This is very helpful!

 

Exhaust valves on the 3.5V6 can tighten w/ mileage due to wear. If over 100K miles, you are due for a valve adjustment. A too-tight exhaust valve can cause missing and lead to valve damage if not addressed.

First make sure it's not a Coil-Over-Plug (COP) or fuel injector.

#4 is the pax side cylinder on front engine bank.

Aftermarket COP'