cduncan01

Hi everyone,

I just joined this forum due to some troubles I have been having with my 2001 Honda Accord. Hopefully some of you have much more experience than I do with fixing Honda's (I have basically none) and may be able to help me troubleshoot how to fix the issue. For some background, I drive the following vehicle:

• Model: Accord, LX - V6
• Year: 2001
• Current Mileage: 140,000

Over the past year (since sometimes in the Summer of 2023), I have been getting misfire codes. I always get the P0300 code, as well as some individual ones (before P0301 and P0304, but now P0302 and P0304), and now I am getting the pending P1399 code. In attempt to fix this issue, I have done the following in this order:

1. Replaced the spark plugs with Honda at the Honda Dealership.
2. Replaced the ignition coils with a pack of 6 Duralast coils from Autozone. I have tried swapping these around but the codes do not move to new cylinders when moving ignition coil positions.
3. Cleaned the EGR port and replaced the EGR value.
4. Performed a Valve Adjustment.

Despite my efforts, I am still getting these codes. However, the car is running very smooth, making the troubleshooting process very difficult. My plan next is to try replacing the Fuel Injectors. However, I would like to avoid continuing going down the rabbit hole of what could be the cause of the misfires so I am hoping that you all may have some experience that can guide me in a better direction. I suspect that the P1399 pending code is a clue to what could be causing it.

Based on the provided info, has anyone experienced an issue similar to the one I am in and if so, were you able to fix it? I appreciate any help anyone has!

Thanks

95_civic_gsr

I had a similar experience with a 2006 Pilot. It seemed like right after an oil change, it would throw those codes. I'd clear them, and they would be gone for 3 months or so, usually until after the next oil change. I'm not sure what fixed it exactly. I believe it was due to a faulty timing belt tensioner allowing the cam to have just enough slack to cause issues. I didn't find this out until after I changed all the plugs, coil packs, cam plug seal, cam seals, valve cover gasket, VTEC&ECO solenoid seals. When I started adjusting the valves, the rear cam would jump as I turned the crank. Then I found that the timing belt tensioner had given up. So I changed the water pump, Timing belt, tensioner, idle pulley, crank seal. I made the connection of the misfires with my oil changes, so I assumed oil was getting somewhere it shouldn't be, and shorting out the spark until the oil leaked out enough to lower the level below causing problems. However everything looked really good as I pulled the old parts off. Except that timing belt tensioner. Also, after I had done all this work, I found something that You Should Try First!

Coil Pack Springs

They used to be $10 for the set, now they are $45 for a set of 6, and $10 each if you want to get them just for the cylinders that are misfiring. But if you buy 3 then you might as well get the set.

I'd try checking for missing or collapsed coil pack springs first. Also, check the spark plug holes just in case the springs fell out into the hole and are shorting out the spark plugs against the head somehow.
I would assume that whomever adjusted your valves, would have picked up on the jumpy cam gear if your tensioner pulley was out.

EDIT: After re-reading: I see that you replaced all the coil packs with "pack of 6 Duralast coils from Autozone"
This should have replaced the coil pack springs I just mentioned above, so I guess that's not a viable solution.
Might pull the back cam inspection cover, and watch the cam as you turn the crank for any popping.