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Discussion Starter #1
So I finally got my first check engine light today and I took my car to autozone right away to get the codes pulled up and here they are:

P0301 Number 1 Cylinder Misfire Detected
P0304 Misfire No. 4 CYLINDER
P0306 MISFIRE No. 6 CYLINDER
P0300 Random Misfire
P0301 Number 1 Cylinder Misfire Detected
P0304 Misfire No. 4 CYLINDER
P0306 MISFIRE No. 6 CYLINDER
P0300 Random Misfire

That's exactly what it says on the sheet the guy at autozone printed out. Not sure why it repeated it twice. I have a 2005 MDX with 99,6XX miles on it. I purchased the car when it had 91K miles last year and the previous owner already got the timing belt and water pump replaced and I myself got a tune up for the whole car (air filters, oil change, tranny fluid changed, serpentine belt changed, spark plugs changed, new tires, new front and side motor mounts). The guy at autozone thought I needed a tune up and perhaps new plugs. I'm a noob when it comes to cars, what do you guys think I should do?
 

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Has the car had a valve adjustment done? It would have been kind of a shame if the PO went to the trouble of swapping the plugs without doing that, but some folks just don't think about adjusting valves (since the vast majority of modern cars don't ever require that by virtue of having "self-adjusting" hydraulic lifters). At around 100,000 miles it's common for the valves to get tight enough to start causing the same problems you're having.

You'll need to do a valve adjustment on it anyway (assuming you're going to be keeping it for a while), so there's little down side to doing it now to see if it cures your problems. I'm betting it will, but if not, it's just required maintenance being done when the factory says you should do it.
 

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Discussion Starter #3
I haven't gotten it done. My mechanic told me he thinks valve adjustments aren't needed. How much will it run me?
 

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FWIW, your mechanic is wrong (though I'm sure there are others who don't realize that our Honda 3.5 liter V6 engines don't have hydraulic lifters). I did them myself - it's really not a huge job, though it's pretty fiddly, and not for those who aren't comfortable with creating a pretty impressive pile of parts taken off the engine to get to the valves. I've seen a lot of estimates but I'd guess most shops would charge between two and four hours labor. Here's a thread that seems to cover a lot of info on the subject...

http://www.mdxers.org/forums/73-first-generation-mdx-2001-2006/40784-valve-adjustment.html
 

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I concur, valve adjustment needed, take it to a reputable shop familiar with the process. I'm hesitant to say, but if your not comfortable doing it by yourself, take it to the Acura dealer, pay the premium to have someone versed in the process do it.

Sent from my XT1585 using Tapatalk
 

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+1. Many engines might not need regular valve adjustments, but these ones do. Your exhaust valves have almost certainly tightened up by now (that's the tendency with these engines). It's not hard to do, but it can be time consuming and parts of the job are annoying (e.g., getting the rear valve cover off/out). A good mechanic should be able to do it in a couple hours. A good Honda/Acura mechanic should be able to get it done in one hour. The cost is mostly labor (depends on whether or not you replace seals while you're there), so expect to shell out a couple hundred for somebody else to do it (not the worst repair bill in the world), but whether you want to do it yourself (if so, there are a few walkthroughs on this forum) or have somebody else do it, you should still get it done.
 

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See my other thread, I had the EXACT codes you had except for P0306 and it WAS valve adjustment.

Any Honda / Acura mechanic who knows their job knows that they need Valve adjustments (Fords and many many other cars don't).
Time for a new mechanic. It will cost you about $350. (Because it's 3.5 hours of labor and about $40 of parts)

My mechanic got the 3.5 hours of labor from his Computer program that does that (Allstates or something like that).
You take off the manifold (1 hour), the valve covers (.5) hour,the spark plugs (.5), adjust the valves (.5) and put it all back (1.0)

If 'pibcak' thinks it's 1 hour, then either I got ripped off, my mechanic uses the wrong kind of software (which shows the parts involved and the instructions of what to do) or pibcak is thinking of something like an old Civic (Which is about an hour)
 

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The 1 hour estimate came from a comment SuperTech (a certified Acura master technician who used to be a regular on this forum) made in another thread that he could round-trip the job in 45 minutes. I did the job on my '06--the first time I'd ever done it, so I was going pretty slowly--in about 4 hours. If a professional mechanic charged you 3.5 hours, his program might have built some padding into that estimate. Even so, a $350 repair bill once every 100k miles isn't so bad.
 

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Discussion Starter #9
Well here's an update. Before I took it to the mechanic I purchased Liqui Moly Fuel Injector Cleaner and it cleared my light. Then a week later the light came back on and then went away the following day. So I went ahead and purchased another Liqui Moly and poured it in my next fill up again just to make sure to clean the fuel injector's real good and when I got to work I used my friends OBD scanner to see if I still get codes even though I have no light on and behold I did. It also brought my check engine light back on which went away a day or two later. So I said enough is enough and I took it to my mechanic and he said that I had 3 bad coils and it damaged the spark plugs. Recommended I change out all the coils and spark plugs and I also changed my brakes and two front rotors and I also got a oil change. After all was said and done, it came out to 860 bucks! I'm going to go to work again and if I still get codes I'm going to be very pissed off!
 

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Well here's an update. Before I took it to the mechanic I purchased Liqui Moly Fuel Injector Cleaner and it cleared my light. Then a week later the light came back on and then went away the following day. So I went ahead and purchased another Liqui Moly and poured it in my next fill up again just to make sure to clean the fuel injector's real good and when I got to work I used my friends OBD scanner to see if I still get codes even though I have no light on and behold I did. It also brought my check engine light back on which went away a day or two later. So I said enough is enough and I took it to my mechanic and he said that I had 3 bad coils and it damaged the spark plugs. Recommended I change out all the coils and spark plugs and I also changed my brakes and two front rotors and I also got a oil change. After all was said and done, it came out to 860 bucks! I'm going to go to work again and if I still get codes I'm going to be very pissed off!
I think it's odd that 3 of your coils went out at the same time. My bet is you'll be going in for a valve adjustment shortly. I got similar codes on my 2004 MDX with similar miles and the only thing that permanently cured the check engine light was the valve adjustment.
 

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I'm with onid on this - the odds of six coils working perfectly for 100,000 miles, and then half of them failing all together - essentially zero. If your mechanic didn't do the valve adjustment while changing out the plugs, he ripped you off, IMHO. You will be doing that shortly one way or another, and will be retracing the steps he took to get to the plugs (about 2/3 of what it takes to get the valves done).

PS - I hope I'm wrong (but I'd bet dollars to donuts that I'm not).
 

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Discussion Starter #12
Let's see how it goes. The mechanic is a trusted friend of my dads. I don't think he will do me wrong. He even gave me a discount. He said he changes 1 coil alone for 125 bucks.
 

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Discussion Starter #13
Update! So my light kept coming back and my mechanic kept telling me its because my fuel injector cleaners are dirty and to keep using chevron techron to clean them out. But I've used liquid moly twice and it gets rid of the light but the light comes back after a few weeks. Anyone got sick and tired of dealing with this check engine light and I need to get my valves adjusted anyway, so I went ahead to a local shop and had them do it and boy am I glad I did. The car runs much smoother! Can hardly even hear the engine now and it idles beautiful. If anyone is on the fence about getting their valves adjusted, do it! Hopefully the light doesn't come back again!
 

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I'm new here. I own an '06 MDX Touring with about 212K miles on it. And I have P0300, P0301, P0304 and P0306 codes. Read about it on the internet. Almost everyone is saying valve adjustment. It's time for the second 105K maintenance, so the Acura dealer service person recommended doing that with the hope that the valve adjustment as part of the procedure would fix the problem. Nope, they turned the CEL and VTM-4 lights off, both came right back on soon after started. When the day comes, I will scan it again and see what kind of codes it will show. Things they supposed to have done that I think may help with isolating the problem: Replaced the spark plugs, adjust the valves. My guess would be if the codes are still same, I'll check the coils of each spark plug. Is there a distributor on it? Correct me if I'm wrong, but I think distributor only exist with carburetor vehicles, right?

Stay tuned for updates and questions.

Thanks!
 

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If you're getting misfire codes for only one or two cylinders, the best thing to try is swapping coils around to see if the problem follows the coil (in which case you just replace that coil) or if it stays with the original cylinder (in which case you keep looking for the problem). Sometimes the clue is that all the cylinders are on the same side (so look for fuel feed or maybe exhaust restriction issues).

Yes, only older vehicles have a distributor, but there's no direct correlation between having a carburetor and a distributor, other than before a certain date, all cars had both. There's no distributor on the MDX - like most modern vehicles, it's got coil packs which are fired individually by computer control. The good news is, a failure will only result in a rough running engine - the bad news is, you have more things that can fail (though let's face it - the failure rate is a fraction of what it was with points and an old-school distributor).
 

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Okay, here is an update: Scanned the computer and I got back the exact codes before the timing belt. Supposedly, if the technician is truthful and that he really adjusted the valves, now I am leaning toward a fresh pack of coils. I also notice that on my code scanner screen (while displaying the codes), CAT, EVA, O2S and EGR all flash together. I'm not familiar with what each actually means. I'm using an Innova ScanTool ABS-SRS model scanner. This weekend, I will try to swap them around and see if it follows.

Is the '06 still having problem with the EGR like prior models? I may also lean toward that as well if '06 is no different than prior models.

Any heads-up before by anyone will greatly be appreciated.
 

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Discussion Starter #17
Habbyguy, when you get a chance, check out my wheels thread. Wanted to know if all RDX rims fit my 05 X. The ones I'm looking at is for the 12-15 RDX.
 

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Done. It's funny - I DID post a reply (with a photo) to that thread, and even remember seeing the site update the thread (to make sure the photo came through OK). Not sure what happened, but it disappeared. I remembered the details, so just did a new reply (with the photo again).
 

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JCNiest5, anything is possible if you're getting the same misfire codes. At any rate, you should know if the coils are suspect after you swap them around. You might try doing just the front (easy to reach) coils - if the problem doesn't follow the coil on the front bank, chances are overwhelming it won't on the rear bank either and you would have saved the aggravation of laying over the engine working out where those pesky coils are bolted down. ;-)

I wonder if the EGR, O2 sensor, EGR and cat "codes" are really readiness indicators. Those indicators are what most state inspection stations use to determine if your car is OK or not. If the tech disconnected the battery, the readiness indicators will reset to "not ready". They reset after driving a certain amount of miles and a certain number of start/stop cycles. Most times you don't worry about it, since it won't really affect the way the car behaves at all. It's only a problem when you're trying to get a car through inspection, or when you might have issues in those areas (basically, emissions) where the indicators might be throwing off your troubleshooting.

If there's a P0XXX code associated with those emissions-related issues, that's a different thing. But if not, those will probably just sort themselves out after you drive for a week, especially if you have a number of starts / stops, and spend a reasonable amount of time just cruising at a steady speed. Do a google search on "drive cycle" for an MDX and you'll get more specifics (or just ignore it and it'll probably go away, disproving another old saying).
 

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There's a noticeable random noise, I can't really describe it, more like plucking, or really low tone ticking sound, like that of a wooden sounding block, coming from (or closest to) where cylinder 6 is located. Broken valve? Hope not! Hopefully I have time to work on it this weekend. It's super cold here in MN, so I put the SUV in the garage, but no heat, so it'll be hard to work on it for sure.
 
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