Hi everyone, new here to Honda-Tech and semi new to Honda's... Not new to old vehicles or wrenching on them but I am nearing my wits end with my V...

I purchased the car some months ago with 254k on it, which I wasn't scared by at all. Engine bay was clean, no rust, clean interior - Great. First time I started the car before purchase, it ran then died. I fired it back up at the dealer, feathered the throttle and kept it running, took foot off and it died. So I continued to do this on a make shift test drive to see if the vehicle was "roadworthy" at all. It passed.

Since I've owned this car, now 261k I have been hunting this issue down to try and get this thing running right. I've pulled the codes for P0300? I believe, it was as well as 0301-0303. I've checked the condition of the ignition system and replaced components as they seemed fit. I first started with a valve adjustment, which immediately cleaned up the idle and drive quality... Temporarily, and then the roughness and miss returned - But with a slight improvement.
Next I moved onto to the plugs and wires, inspected and replaced them all even though they appeared in good condition and again... Marginally better, but still not right as rain. My last swing was just a simple seafoam through an empty tank and I topped it off with 93RON (used 93 by accident), and this was the BIGGEST improvement. By blinking CEL went away, then returned as only a solid CEL up to 50 miles into this tank of gas, and then back to a blinking CEL.

Worth noting, when I pulled all of my plugs cylinders 1-3 plugs looked MINT, cylinder 4 appeared to have some oil on the plug itself? Not from the tube shaft but inside the head? But I am getting no smoke through the exhaust at all, so I'm not sure if/where the oil is coming from or if maybe I am getting incomplete combustion in cylinder 4 and seeing partially burnt fuel - Hence the improvement in condition after running the seafoam.

I am thinking this may be a fuel issue at this point? Maybe a fuel filter or fouled injector would cause this? I've just seen so many people have such vastly different issues with these B20's with very unique solutions. I'm hoping someone out there can point me in the right direction after what I've corrected under the hood. Not afraid to keep spending money on keeping this car running, but I feel like I'm blindly throwing $100 at it on my days off... Any advice is appreciated!

 

It is pretty common for these engines to burn valves if the valve adjustment is left out of spec for too long. It might be worth doing a leak down or compression test to see if you have burned valves that are tripping your misfire CEL.

 

For some reason Honda used a different valve adjustment timeframe, this caused a lot first gen V's to burn valves (going much longer than any other B-series released). I would look here as stated by Rico.

 

I have considered the valves being burnt up... I’ve been trying to rule out anything besides this, and everything I’ve replaced so far (picked up a new fuel filter tonight) is just routine maintenance overdue on this V.

I’ll do a compression and leak down test and see what I get... If I’ve got bad valves I’ll probably look into a B18C head swap, because why not.