SovereignAce

Hello guys. To be short, I have a second cylinder misfire, but this a rather long story so sorry in advance.

The tale begins about a week ago, when I started getting p0300-p0304 and p1399 codes. I figured it just needed new plugs, wires, rotor, and cap, so that was my first step. After replacing those, I had eliminated p0300,p0301, p0303, and p0304. I was surprised the cylinder two misfire remained, so I went ahead and replaced the entire distributor, despite having already replaced the cap, rotor, etc. I figured this way the ICM and ignition coil could be removed from the suspect list. Even after this, the misfire remained. I played with the timing a bit, but nothing really changed. I could move the distributor almost fully each way, and nothing helped. I swapped the wires around and switched the plugs, but they all checked out. The misfire is unnoticeable at higher rpms, but at idle and low rpms its pretty apparent.

After deciding the problem was most likely not within the ignition and electrical system, but with no real direction, I began troubleshooting the mechanical side of things. The first thing I did was a compression test, which finally revealed some useful info. Cylinder two was at 30, while the others were around 130-140. I did a wet test of cylinder two as well, and it had a very minimal increase of about 10 psi. Figuring that maybe I had a slightly bent pushrod or something of the nature, I removed the valve cover. Everything seemed to be in working order, and all the cylinders moved very smoothly. Also checked to see if any of the valves needed adjustment, and they were all fine.

Which brings me to now. After replacing the valve cover, I decided to just go ahead and start it again to make sure I had correctly reassembled everything. Instantly, a small amount of smoke came out of the engine. I thought it was just oil from the wet compression test, but then noticed it was coming from the manifold. I noticed a few leaks and small cracks on the manifold, with most being on the second cylinder "tube" of the manifold. Since all the 'tubes' connect, could the loss of pressure in the manifold be causing a misfire in just one cylinder? Also, wouldn't other codes besides p0302 and p1399 be showing? I would imagine maybe some emissions codes or something of that nature would pop up as well.

Any help is welcome!

As it is, the car is not being driven. Thus, I cannot report on how it behaves once its been running for a while, etc.

Thanks!

24TEN

iTrader: (2)

Which manifold are you referring to?

I'd honestly say that you have something much more involved than a bad sensor or ignition component. A low compression reading is pretty much a mechanical failure. Besides the rings themselves the only thing I can think of off the top of my head is a bent valve (like you suggested) or a burnt/chipped valve. A bad head gasket is possible but I think you'd experience much more than just a misfire if it was.

SovereignAce

Oops, I meant the exhaust manifold. The internet seems to be torn as to whether or not a cracked exhaust manifold can cause a misfire due to lack of pressure, so i figured I'd ask people in context of the problem. I personally don't think its the problem, but it cant hurt to ask.

As to the head gasket, I had a very Honda-experienced friend and his father (who owns a repair shop) tell me that they strongly suspect a cracked head gasket that is just beginning to fail. I think this is far more plausible, and I guess tomorrow I'll begin the tear down. If nothing else, at least I will be able to check the valves and everything else while Im in that deep, so it will be fixed one way or the other.

tanker405th

I had a similar problem throwing those codes, and a few more a couple of weeks ago. Low compresson on number 4. My exhaust manifold is fine btw, with no cracks. Pulled the head and had a burnt/chipped exhaust valve, which explained the detectable change in the exhaust note along with the other list of maladies that came along with it. Took the head to the machine shop and had it repaired (4 valves total, one chipped, 3 others out of tolerance), installed new water pump/timing belt since it was off, and now I'm back up and running. Good luck!