I have a 2021 Honda odyssey that keeps going into limp mode and giving a check engine light. When I read the codes it’s various cylinder misfires. I have replaced all of the ignition coils and spark plugs. But it’s still happening. About once a month. The spark plugs never look fouled. It makes me think something else is causing the misfire.
@chucktobias they did not test bad, I started by swapping plugs to see if the discrepancy followed. It continued in various positions, so I ended up just changing them all.
@gram1289 I wouldn't think a 3-year-old Honda would need those things unless the miles are really piled on the thing, though of course anything can go wrong at any time. You might want to take a look at live and freeze frame data to see if anything looks out of whack.
@chucktobias I had a shop look at what I think you are referring to. He said he watched it run for 5 minutes and everyone once in a while he would see a tiny blip on the radar that would indicate a misfire, but that it wasn’t bad enough to throw a cel every time.
@gram1289 It's hard to tell from that description what they were actually seeing. It's true that a problem has to reach a certain level before throwing a code but looking for codes is just the bare beginning of the diagnostic process. More interesting would be what was going on in the data when those "blips" occurred.
@chucktobias I noticed a crummy repair on a threaded insert where the EGR pipe mounts to the intake manifold. Looks like someone stripped it out and jb welded a nut in there. But why were they removing the EGR pipe to begin with?
@gram1289 Sounds sketchy to me. Could be a bit of a vacuum leak there. The thing is that vehicle is only a few years old and that's the kind of kluge you typically find on the kind of decades-old beaters that I drive. I have no idea why that "repair" was done.
@chucktobias I also forgot to mention that the carfax showed this vehicle failed emissions test in California two years ago. That’s got to be related right?
@gram1289 Could be related. Of course they're pretty much insane in that state when it comes to "smogging" vehicles but a 3 or 4 year old Honda should not be having these kind of problems. I have to wonder if there is something nasty in that vehicle's history that wasn't reported to Carfax.
@chucktobias that’s what I’m afraid of. It runs great for months between the misfire spells. I looked back at the CEL print outs and there actually were a couple of ECM failures paired with those misfires.