Maxxx

I used this board to solve a misfire on CYL 3 a few moths ago. A bum coil pack was the culprit.

Car has been idling rough at times for the last month or so. But never bad enough to trigger a CEL. CEL finally came on a few days ago, misfires on 5 and 6 now.

Seems unlikely that both coil packs would go bad in the same 30-day span . . . but will test for that in the morning if the rain stops. Anything else to consider with 2 cylinders misfiring?

Any vacuum or fuel system components that would be specific to those two cylinders?

I initially suspected fuel, as the problem seemed to be more frequent whenever the tank got under 1/4. But it would sometimes happen when near-full so that could just be coincidence.

Anyway, thanks in advance.

justnspace

iTrader: (1)

#5 likes to eject.
I'm betting that you caught it before it shoots through the aluminum!!

alas, I'm guessing...get in there and check it out!! interested in what you find!

Maxxx

Um, #5 likes to eject what . . . ? A valve?

Maxxx

Visual inspection . . . is this a missing vacuum line? Can't see where it would connect to, but seems like there *should* be a hose connection here.

Maxxx

Mounted in back of engine well, one line runs into the dash. 2nd post looks like it should have a hose going somewhere . . . or at least be capped?

Maxxx

But this is a more likely culprit . . . plug #6

Rust / corrosion is never a good sign

Time to bust out the compression gauge I suppose

Skirmich

What Justin meant is that number 5 and 2 plugs like to undo themselves and eventually eject from the threads, You gotta lookout for those..
That part looks like the transmission breather tube filter, This is what it looks like on my 2G MDX:
The tube beneath it goes into the Transmission Case, The tube on the side remains open.

Maxxx

OK, thanks . . . I knew that was going to be too easy of a fix

Compression was actually fairly consistent across the cylinders I tested. 130-140 for all 4 tested cylinders. 6 was 140, 5 was 130, 4 was 130, and 2 was 140.

Every coil pack looks OK (idles roughens when unplugged, smoothes when plugged back in). Was obviously hoping that would be it. Ah well.

I swapped coil packs 2 & 4 for 5 & 6 (the ones giving the initial misfire code. Guess I'll just wait and see if the next misfire code is still for 5 & 6?

Maxxx

Well, fresh codes today on 5 and 6. Car is running well enough, just frustrating to get those codes. Idle will roughen up at time for a few seconds, then smooth out.

Coils all seem fine. Plugs seem fine (I cleaned, tested, and re-installed the plug shown above). I'll pull it again in 500-1000 miles and see how it looks.

History on this car includes ongoing misfires for #5 going back about 2 years. Had a misfiring #3 a few months ago which turned out to just be a bum coil.

Valves have been adjusted twice by the dealer (former owner), never cured the problem. Cracked head or blown gasket was suspected at one point, but it has never eaten water and just doesn't act like a car with a compromised head. Injector for #5 was look at in place, look good. Valve lash looked good. Leak down ok,

So where to go? I want to sell the vehicle but don't want to just pass along the problem to the next guy. What is the next step?

That plug in 6, along with some sign of fouling above the thread, looks pretty lean. Plug has been in there long enough to show some sign of doing work.