Taylor M Ward

I've been having misfiring troubles with my 2005 Honda Accord on and off since early November 2015.

The first time it happened, I took it to the shop and they told me it was the spark plugs, put a new set on and I was good to go. No troubles for a month.

December comes, and it starts misfiring again. Take it back, and they tell me the DTC was P0302, and that I needed a new coil pack on cyl 2. When they put the new coil pack on, still misfires. So they put the original back on and sent me on my way.

I take it to my parent's mechanic, where it won't misfire for him at all. The only code he got was P0420. Told me eventually I'd have to replace the Catalytic converter, but it wasn't a pressing issue now and wasn't causing the misfiring that I was describing. Gave me back the car, again with no real answers.

Since then, I have changed the plugs and coil packs, still misfiring. I routinely get the P0302 code, and have once gotten the P0420. I'm hoping it not a compression problem. So here's my question:

Can a bad catalytic converter cause a rough idle/ride? That's the only thing I know is going bad, but have heard mixed reviews on whether it could be a cause of my engine-missing problem.

Thanks in advance for your help!

Accordian47

A bad catalytic converter is typically not going to effect the idle or quality of ignition in the combustion chambers, however a bad catalytic converter may be caused by misfires as poor combustion allows unburnt fuel to build up and burn in the cat, destroying the metals and medium inside.

It would be best to check compression on all the cylinders as its a pretty easy task, your misfire may be compression or fuel related as well but if your getting a P0302 then there is an ignition misfire detected by the ecu. Replacing plugs and coil packs is a good idea as they are typically the cause and make up a good percentage of the entire ignition system. Other possibilities are the ecu or bad wiring somewhere.

DCFIVER

Good info^^^^^^^^^^^^^^









A common issue for misfires are tight valves. I suggest checking the valve lash.