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I just got a check engine light for 4 cylinder misfires- 1,3,5,6 as well as the torque convertor. Does anyone have any idea what it might be? I just did park plugs 30,000KM ago and I checked the spark plugs and theyre still okay.

Any suggestions on what I should do? I can do the work myself.

The car has just under 212 000KM
 

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After clearing codes does this misfire feel like its missing or cant feel anything at all?

Try if this is felt missing in morning when cold or when hot?


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Hi All, I just joined after getting help from this site for a P0305 code for my 2006 MDX I've had since new. I ended up adjusting the valves and found spark plugs #2 and #3 needed tightening - about 3/4 turn and 1/4 turn, respectively. It has 141K miles with last valve adjustment at about 83K miles after getting a P0175 code.) Here's the sequence I went through, one at a time (with some learnings after the fact). MIL reset with battery disconnect each time.

1. Swapped coil #5 with coil #4.

2. Inspected and then swapped #5 spark plug with #6. (Should have checked tightness of all plugs.)

3. Swapped ignition coil relay with horn relay. The logic was to swap with a relay that isn't used much. The ignition coil relay is located in front of the PCM, behind the passenger headlight, in a 4 relay box. The relay is the only 4 pin relay of the four.

4. Cursory check EGR. Removed, checked if passed was clogged or valve appeared open. Didn't have a code so didn't worry about too much.

5. Since they were way easier to get to, checked the valve clearance on the front cylinders - 4, 5, 6. Started with #5 but found all exhausts were below spec (tight) at about 0.008 and intakes were above spec at 0.010-12. Specs: Intake 0.008-0.009 inch, Exhaust 0.011-0.013 inch. Heads < 100 deg F.

6. After R&R of the plenum, found the same/similar valve clearance in the back bank. The is when I found the two slightly loose plugs.

Reassembled and restarted. Runs smooth and quiet. After all this I wondered if I set the valve clearance backwards at 83K or the two loose plugs had a part since #2 fires before #5 and then #3. Well, at 83K, the intakes were fine so I left them alone and most of the exhausts had no clearance.

Hope at least some of this helps. I appreciate all the contributors for helping me. Thanks!
 

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How long did it take to do the adjustment?
The valve adjustment took about 1.5 hrs for the front and 3 hrs for the back. The 1.5 includes the time to do a pretty extensive wipe down of the top and esp under the plenum, and around the valve cover/head interface to keep gunk from falling into the valve train. The back took extra time to R&R the plenum and similarly clean the valve cover/head. A few hassles for the back (for me) included not being able to figure out how to remove the injector cable tray, basic reach distance, and getting a good position for the feeler gauges - had a few redos. The cable tray moves enough to get the cover off but there was some manipulation required. I was by myself so cranking the balancer and aligning the cam gear to TDC was tedious. A helper could watch the cam gear and speed things up.
 

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If you did not use NGK plugs than you will have a misfire on your vehicle.
I've read this before, but can't imagine it's true. Yes, I'd certainly recommend using high-quality iridium plugs, but AFAIK, there isn't anything magic about the NGK plugs (or anything wrong with 'em either).

FWIW, I replaced my plugs with Bosch 9604 two years ago during a valve adjustment. I haven't seen a single misfire code in that time, and the vehicle runs as well as I'd expect it ever could, and gets "proper gas mileage". And FWIW, I paid a whopping $5 a pop for my Bosch plugs.
 

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I found an error in my post above and seems I can't edit it so adding a reply here. The location of the ignition coil relay in Item 3 in my post above is wrong. The correct location in an 06 per my factory service manual is above the passenger side fuse box in the cabin. It's a block of 4 and it's the relay nearest the passenger side front tire. It is the same relay as the horn. So the swap in Item 3 was not done (at least with the ignition coil relay).
 

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I just recently had the valves adjusted on my 2001 for the first time. I was at around 188,000. Spark plugs have been changed at regular intervals with NGK's. My exhaust valves were tight. I haven't noticed any difference in starting or driving the car. Only that my gas mileage MPG has jumped way up (+25-30%). Town / mixed = 18.5mpg, backroad / highway 20.7mpg.

Local honda mechanic did the adjustment = 2-hours time ($190) + 2 gaskets ($33.28). Dealer is $500+
 
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