2005 Honda Accord repeated misfire code

honda
accord

#1

I have a V6 2005 Honda Accord. 200000 miles. For last few years I get a CEL. Code reads misfire P1 or random misfire. I have replaced the ignition coils and had the software updated. Takes care of problem for awhile, but it comes back. I would think new coils would last longer. Could something else be causing misfire code ie wiring, vacuum?


#2

With 200k on the clock, the engine could just be old and losing compression causing a missfire. Did you change sparkplugs when you changed the coils? You probably should as it will give you a good idea of the condition of the engine. A compression test at the same time would tell you a lot as well. Do that and post back with the psi readings from each cylinder and condition if the plugs - sooty, wet with oil or fuel, color of the electrodes. I doubt the coils are bad.


#3

Thank you for the reply. Did change the plugs around 130000, but not since. No one recommended that. Thank you for the suggestion on the compression, will have it tested. Son has car now before his PCS to Germany may be a few months until I can get it checked. All lights are off at the present time. I should have mentioned that the car never seems to run rough even with the CEL on.