Hey there, I own two Accords the one in question is a 1998 Honda Accord V6 4 door 200,000 miles. I just recently bought the car a few months ago and have replaced the fuel pump, Idle Control Sensor, Fuel Pump Relay, Battery, Power wires from battery to starter, spark plugs. I am having multiple misfires and it doesn't want to start unless I turn it over 2-3 times and then it will fire up. I have included some screen shots of my error codes what do you all suggest? I am a novice at turning a wrench but I can follow a youtube video or instructions. Thanks for any help and guidance. I did search the forum and I am finding bits and pieces of great advice here and there but I thought it might help to have someone look at these errors together and give me a starting point.

https://imgur.com/NwbPwGs

https://imgur.com/6W9zn1m

 

You need to check your O2 sensor and you intake for leaks (check from intake tube back for cracks and TB for cleanliness).

 

Your freeze frame data shows the misfire code happened when your were in open loop, which means the O2 sensor is not controlling the air/fuel ratio.

I'd probably start by fixing the P0401 EGR insufficient flow. You have to remove the intake manifold to do this, so you can get a replacement gasket. Felpro makes good aftermarket gaskets. It is a metal gasket, so you can probably reuse. Follow the video below.

Then you can move on to figuring out the O2 sensor code. Let us know if you can read live engine data on your scanner, because that will help with the diagnosis.

 

 

When the car is up to operating temperature, look to see if the primary o2 sensors (both bank 1 sensors) are oscillating between 200 and 800 millivolts. Also let us know what the long and short term fuel trims are reading.

 

You guys are awesome! In addition to my 2000 Accord with 260K miles I also have a 2008 Infiniti G37. I've had misfires for the past 5 months P0300 codes. I took the car to both Infiniti and Nissan and neither dealerships could find the problem. I was checking my OBDII reader last week and looked up history. Found that the misfires were all occurring on the right bank. Swapped the MAF's and the misfires were still occurring on the right bank. Replaced the O2 sensor, bank 1 and no further misfires. From now on when I want to find out what the problem is on my cars, I'll post on this site.

 

Glad you got your issues resolved.