All I did was change the valve cover gasket on the 2nd bank (4,5,6), and the plug on the firewall side of the camshaft. That plug was seized in there and it came out in pieces. I saved them as they came off though so I could piece it back together and make sure all of them came out. The new one was a massive pain to get in. I tried everything. I tried a dab of oil. I tried heating it a little in the oven to soften the rubber. I ended up having to leverage it in with a crowbar, which I knew was stupid, and sure enough part of the inner seal broke and the plug didn't seat all the way. @ 300k miles and for as much time as I'd spent on just that one plug, I figured I'd put a bead of red RTV around it. Seems to have worked as it's not leaking oil. But I have a different problem now

I'm getting misfire codes on that whole drivers side bank. I've double checked all the vacuum lines and wiring connectors are in, and they are. Even had a buddy that's a far better mechanic than myself check it out and he couldn't find any stray vacuum lines or anything either. I've pulled each of the coils one at a time and there's rpm drop for each one, which leads me to believe it's not that. I didn't take the injectors out, and you can hear each one of them firing, so I don't think it's that. What's really confusing me is that the misses are intermittent. It starts just fine. It'll idle for about 10 seconds just fine. As soon as it settles into the 750 range, it starts to miss. If I tap the gas, it will stop missing for a few seconds, but then it will miss again. If I hold it at 2k or any RPM for that matter, it will run fine for a few seconds and then start missing. As soon as I let off the gas, it will run fine for a few more seconds, but then start missing again. I can smell either fuel or exhaust gas from under the hood. It also sounds like what I can only describe as a waste gate when I let off the gas, and it also sounds like it would if an exhaust header were loose, but I don't know how that could be the case. I didn't touch it. It was running just fine before I went after that gasket today. So I'm sure it's related to something I did, or something I disconnected. I tried disconnecting the EGR wiring harness via a suggestion I saw on another post and no change. I've seen a wide range of suggestions, everything from the EGR port being clogged to the valves needing adjusted, but I just find that hard to believe considering it ran perfectly before I started messing with it. What blows my mind even more is on the second test drive, it ran fine. No miss at any RPM for about a 4 mile test drive. But then the next time I started it, it was back again. I'm also getting a VSA light and that ! lamp is on after it misses for more than 20 seconds or so. No idea how that could be related to what really feels like either an EGR problem or a clogged cat. The only reason I suspect a clogged cat is that loose header sound may be blowby from the gaskets from too much back pressure. But how the ever loving F would it be running fine and then have a super clogged cat just from changing a VC gasket? One other thing: I don't really know how to describe this other sound I'm hearing other than it's a tiny hiss, followed by silence, and another tiny hiss. Almost like the sound an airbrake makes, but a lot quiter. It's not constant and very brief, but it seems to correlate to the misfiring.

I'm really hoping this might ring a bell for someone on here that can tell me what I need to do, because if not, Murphy's law tells me I'm going to spend the entire weekend trying to track down this problem and I still may not even fix it. I'm thinking step 1, check the spark plugs. The coil packs and connectors all looked like they'd been replaced at some point and in good condition. There was a little oil on coil pack #5, but I attribute that to a leaking plug gasket, the whole reason I was wrenching in the first place, to stop a slow oil leak. Like I said, when I disconnected that coil, there was an RPM drop, and it was the same drop as the others when I disconnected them, so I think it's still good. I'm also considering taking off the intake plenum and checking that EGR port to see if it's clogged, but I really feel like that's not going to be it, even if it is gunked up. I doubt that would be a problem that would miraculously manifest itself at the same exact time I'm changing a VC gasket. Like I said, I'm sure it's related to something I did, like that cam plug on the back of the valve cover. But like I said, there's no sign of even a drop of oil leaking from it. And the engine's probably had a collective hour or so of run time since I put it back in.

Please help!!!! I'm about ready to just trade it in and drop 1k on another car. I only paid 2k for this one and I've put about 20k miles on it. All that was wrong was a slight oil leak. Why oh why didn't I just leave it be and keep dumping oil into it?! FML

 

Did the valve cover rubber seal seat properly? If not then there could be a lot of air leaking into the system. Of course, in that case, you would probably be getting misfire codes on both banks, not just the driver side. Are you sure all misfires are on that bank? That hissing sound reminds me of a vacuum leak and if the valve cover is not seated properly then I imagine there would be a vacuum leak.

I'm also mentioning it because I attempted the same valve cover seal replacement last week and when I installed the seal on the passenger side the seal kinked (difficult to put valve cover back in, seal could detach as you tinker around with the cover and it's difficult to see). I did not discover that kink until I put things back together, had to pull it out again, then I noticed the treads on one of the studs holding the valve cover were stripped (that is why it was not torquing properly) so I attempted to undo the stud it with (cheap) crow foot wrench, wrench broke and metal piece fell into air vent down into crankshaft... see my post "Help. Foolish and unlucky (photos)" from 9/13/19. I too wish I had just tolerated the slight smell of oil from the few drops falling on the exhaust manifold... alas...

As far as valve adjustment, I imagine this is a first generation RL so it should have the C35A Honda engine which has hydraulic valve lifters, so there is no need to adjust valves.

I did not notice the "plug on the firewall side of the camshaft" that you mention.

 

On second thought, perhaps the driver side crankcase is vented back to the driver side bank intake only, so indeed that may cause misfires on that side only. I'll have to look at it tomorrow.

 

Thanks for the reply. Today I'm going to retrace my steps so I'm gonna pull that valve cover off and make sure it's seated. I'm leaning towards yes just because the missing isn't constant. I'd think if that were the case it wouldn't just be an intermittent misfire. The plug seals that came with the kit have tabs on the inside of the ring so you can see that they're still in position after you put the VC back on, so I know it's not those. And I used a swivel attachment to get that lower front bolt next to the strut tower, it wasn't a pain at all and didn't strip, but I'll double check that to be sure. Thanks for the tip.

When my friend came over to help, he brought a scan tool. It dropped a p0300 for random misfires, p1204-1206 for misfires on 4, 5, and 6, a code on the EGR system (can't remember what exactly, but he's gonna help me out again today so I'll check again), and a p1399.

That plug; sorry for the poor description. Was pretty tired. The gasket kit I ordered came with two plugs, one for each head, and they go directly behind the camshaft on the firewall side of the head. Both were leaking oil before hand as well. I did notice the PCV valve was a little loose and it does sit on the dr side bank. I'm gonna wrap some electrical tape around it so it seals better and see if that does the trick, in which case I'll know to replace it. Well, I'll replace it anyhow, but I'll know that was the problem. That intermittent missing is what gets me. Idk how it's possible I was able to get a test drive with no problems or misses. That just screams ECM to me, but the chances of that going out exactly as I work on the car? Idk. I did disconnect ground before I did anything to it. After sleeping on it, I wonder if maybe something in the harness was old and janky and moving it around caused a break/short. But then you'd think it would just be for one or maybe two cylinders, not all 3 on that side. I'll stop back and let you know if anything changes or I get it fixed today.

 

Another few notes: It does seem to go away under high load/high throttle settings. And that air brakey/ intermittent hiss I was hearing sounds like it's coming from the back of the intake plenum. It sounded a little worse today, more like a faulty solenoid or valve trying to open/close. Was almost like a clicking sound today. Hope that helps narrow it down. I checked that loose PCV and under suction it seals right up, so doubt that's causing any issue.

Thanks again for any help. My knuckles are sore and bruised, think I'm gonna hang it up and just relax today. It's not going to do anything but agitate me. If it were something I could see- something not connected back up or something like that, it would be one thing. But I've gone over it for hours and I took pictures before I started removing things. Everything is back where it came from. I'm completely stumped and I feel stupid so I'm done for the day.

 

Ok, good news. I hit up another buddy that has a lot of experience dealing with imports, and ran him through what I was dealing with. He knew exactly what it was.

So there's a bracket on the front of the valve cover that holds that splice connector for the pre cat O2 sensor lead. Typically whenever I do work, I'll wait until I've done a test start to make sure everything is running as it should before I worry about refastening all the little fiddly bits like that. My buddy tells me Acura is notorious for grounding stuff to the valve cover, so even if it seemed trivial, there may be an internal ground on that connector running down that bracket and into the VC. So I put that back in and sure enough, purrs like a kitten. Took it around the block and it was just fine. I'm thinking the intermittent nature was due to that bracket bouncing on/off the valve cover. Disclaimer: I did have to take the valve cover back off to get to that bracket bolt, and while I had it off I double checked my gasket and spark plug seals and they looked fine. No kinks like they fell out during install. And all the nuts and bolts were all torqued down when I took it off, so I don't think that was it, just in case you were thinking it was loose at first and in reinstalling it tightened it correctly.

Anyway, just wanted to drop a line and let you guys know what the deal was. I'd have never in a million years guessed that would have caused a full bank misfire. Heading over to another buddy's place to clear the codes and see if it throws any more. I'll let everyone know if anything changes, but so far it seems crisis = averted

A little anecdote: I had a problem with a steering wheel shimmy a year or so back. And it was the weirdest thing, as it was also intermittent. I'd pull off the highway or come to a stop and it would go away, and I wouldn't see it again for several weeks or more. I called the same friend then, and he told me Acura's were notorious for the rims corroding between the brake rotor and back of the rim, and to check my lug nuts. It seems simple and obvious enough but I wouldn't have thought this, typically if that's the case it wouldn't be intermittent, you'd get a shimmy full time. But sure enough, all 5 were loose on the driver's side, and a couple on the passenger. Knowing is not the same as understanding, and experience cannot be taught. Thankful for people that put in the time to learn all this stuff the hard way so us mere mortals don't have to

 

If you have a scan tool you can look at your long term fuel trims, especially how the fuel trims change between idle and higher RPM. If you have strongly positive fuel trims at idle and not so positive at higher RPM that is an indication of air leak into the vacuum system.
The kink may not be easy to see, especially if it kinked on the bottom side which is not visible, or kinked inside the valve cover. In my case the spark plug seals looked fine (I know what you mean with the tabs). But if you have even a 1/16" gap in the gasket all along one side, that is a lot of air leak.
You can get an OBD2 reader that transmits to a smartphone for about $15 these days and see all that scan tool information. Search for "elm 327" on amazon. It's a good thing to have for any car.