Vehicle in question is 2000 Civic with D16Y8 and 5 speed transmission. It's high miles at 253K. I'm getting occasional Codes P0300, P0301, P0303, and P0304. When the codes happen there is obviously bad performance, but then after sitting it goes back to running "normally". It's an old engine and I also got code P0505 long before the misfire codes. The head gasket needs to be replaced as indicated by combustion leak test. Is it all related to that? Why no code for cylinder 2? Any help would be appreciated.

 

I don't know the answer, but if it's any consolation I'm having the same problem (1998 Civic EX, also D16Y8), so I hope someone comes along soon with some wisdom.

Have you done a compression check? I have good compression on all cylinders, both cold and warm, which makes me wonder how enough coolant could be getting in there to cause all these misfires. I'm getting them on every cylinder: P0301, P0302, P0303, and P0304, plus p0300 (random misfire) for good measure.

In my case, this is following a serious overheat that I didn't notice in time because the temp gauge looked normal until the very end. Maybe that was due to air pockets in the cooling system? But if so, what caused them? Could the head gasket have already been blown before the overheat, causing it rather than being caused by it? I did have a previous, less severe overheat due to a bad cooling fan switch a few weeks prior to this, but the car ran fine after that until this.

I don't have a combustion leak tester, but coolant overflows (very, very slowly) out of the radiator if I run it with the cap off, and coolant drained from it has an iridescent film (aka gasoline rainbow), so I'm pretty sure the HG has to be blown. But you'd think then it would misfire on the one or two cylinders adjacent to the leak (with reduced compression on the affected cylinders), not misfire on each cylinder equally. Are there four separate tiny gasket leaks, one on each cylinder, all leaking the exact same amount so the compression stays between 135 and 140 psi on all of them? That sounds pretty bonkers.

Anyway, as you can probably tell I'm slowly losing my mind over this, so anyone with some ideas for me or OP would be welcome. Thanks in advance.

 

Sorry about your issues, but maybe we can each get some solace knowing we're not alone! I think we're both on the right track, though. I haven't done a compression test, but the fact that you have good compression with those codes is interesting. My engine may have overheated in the past since I haven't owned it long, but there isn't the least bit of overheating now, even though I live in one of the hottest areas in the country. I went ahead and purchased a new head gasket, intake gasket, and head bolts. I bought them from the Honda dealer and am waiting for a chance to do the job. There are many YouTube videos outlining your and mine prospective projects, and it seems very doable. To sum it up I think we are both in head gasket failure, and the problems are related to that. I see ads all the time for people selling Hondas that have "cracked head gaskets, but it still run good". Seems to be pretty common. Thanks for commenting.

 

Have a question for a D16y8 I知 a EK chassis I知 running a p2e ecu doesn稚 let me drive it past 5 RPMs out for first or hit past 5 in any gear any one know what ecu I知 supposed to run ?

 

Wrong computer... try a P2P.