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Discussion Starter · #1 ·
I've got a 2012 with about 145k miles on it that threw the P0303 code yesterday. It also shows pending codes for P3000, P0306, and C1555. I've been reading up on the P0303 code and Service Bulletin 13-082. Since my car is a 2012 it was probably sold in 2011 or early 2012 putting it outside of the extended coverage. The first question is, is there a place where I can find this out? Entering my VIN in the Honda Recall Lookup yields nothing.

Also, I haven't taken the plugs out yet to inspect them (had a wedding to attend so simply no time), but It's at about 5k miles since it's last oil change and the oil level is still at the full mark. On top of that the plugs were replaced 55k miles ago with Champion Iridium plugs which are not OE and I don't know that I would expect a champion plug to last any much longer. combined with the other codes, what are the odds this isn't oil blow by?

Thanks,
Keith
 

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Discussion Starter · #2 ·
Well, I pulled the plugs and got my answer. Cylinder 3 plug is oil fouled. Swapped it to cylinder 2 and the misfire followed. Guess I'll be on the phone to Honda pushing the issue. I've read reference to soaking the cylinder in Marvel Mystery Oil. Is there anything more to it than just pouring some in through the spark plug opening and letting it set for a day or so?
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Well, I pulled the plugs and got my answer. Cylinder 3 plug is oil fouled. Swapped it to cylinder 2 and the misfire followed. Guess I'll be on the phone to Honda pushing the issue. I've read reference to soaking the cylinder in Marvel Mystery Oil. Is there anything more to it than just pouring some in through the spark plug opening and letting it set for a day or so?
View attachment 141627
I've seen worse.
Obviously the VCM is causing cylinder #3 to be dirty (#4 likely black too).
I'd order S-VCM to keep all 6 cylinders running 100% of the time.
I'd plan to get NGK Laser Iridium spark plugs back in the engine. RockAuto sells these at a good price.
Then I'd just do my normal maintenance....,
  1. Have a clean air filter.
  2. Clean the MAF with CRC Electronic Cleaner or MAF Cleaner. Remove, and just a few short burst directly into the electrodes and let dry thoroughly. Reinstall.
  3. Ensure the intake hose is clamped tight, no cracks.
  4. Might consider replacing the PCV valve if it's never been done.
  5. Use a Top Tier 87 Octane fuel.
  6. After the VCM is disabled, take it on some long highway speed drives so those dirty cylinders can burn off the oil deposits.
  7. Changing out the EGR valve may be neccessary to have a smooth idle.
 

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Discussion Starter · #4 ·
I've seen worse.
Obviously the VCM is causing cylinder #3 to be dirty (#4 likely black too).
I'd order S-VCM to keep all 6 cylinders running 100% of the time.
I'd plan to get NGK Laser Iridium spark plugs back in the engine. RockAuto sells these at a good price.
Then I'd just do my normal maintenance....,
  1. Have a clean air filter.
  2. Clean the MAF with CRC Electronic Cleaner or MAF Cleaner. Remove, and just a few short burst directly into the electrodes and let dry thoroughly. Reinstall.
  3. Ensure the intake hose is clamped tight, no cracks.
  4. Might consider replacing the PCV valve if it's never been done.
  5. Use a Top Tier 87 Octane fuel.
  6. After the VCM is disabled, take it on some long highway speed drives so those dirty cylinders can burn off the oil deposits.
  7. Changing out the EGR valve may be neccessary to have a smooth idle.
Thanks. The NGKs were ordered from Rock Sunday and will be here Thursday. Plug 4 was fine. 3 was the only oily one. I'll definitely be defeating the VCM moving forward.
 

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Tangent --

The recall database doesn't list silent warranty or TSB from the manufacturers.
 

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Discussion Starter · #6 ·
Tangent --

The recall database doesn't list silent warranty or TSB from the manufacturers.
Not tangent. Relevant and appreciated. I'm thinking I will call Honda Automobile Customer Service at (800) 999-1009 to see what they have to say. Having gone through my share of issues with other manufacturers I don't expect anything, but I have to try.
 

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I’ll second everything Nail Grease suggested. I bet disabling the vcm with new plugs will probably keep you running just fine. Most of the misfire ones on here look WAY worse. I have the s-vcm and it’s great.
 

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Discussion Starter · #8 ·
It’s been about 5k miles since this event. I did pour a little Marvel Mystery Oil in each cylinder and let it soak before blowing it out and then replaced all the plugs with NGKs, replaced the PCV valve, and installed the VCM muzzled. Then today all you know what broke loose. Wife called and said the car was shaking violently and shut off as she pulled it into a parking spot.

It shows codes for generic misfire and misfires on cylinders 1, 2, and 3. Plugs don’t look too bad. No signs of oil fouling to me. Coils looked dry. Swapped coils from front to rear and the codes stayed the same. When I pull the plug off of each coil the idle varies a little for 1 & 2 in the rear, not at all for 3 in the rear, and drastically for all three front, 4, 5, &6. Any thoughts or suggestions for me?




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Seems you have spark and injector operation for 1,2, 3 as they have some effect when you disconnect coils on each. So pointing to a compression issue affecting 1,2,3 which is either VTEC for Bank 1, or VCM, which only messes with 1,2,3. Haven;t read up on code setting criteria to understand how 1,2,3 could be compromised without setting the CEL.

If you were motivated you could pull the accessible control solenoids for Bank 1 and check for obstructions.

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Discussion Starter · #10 ·
A little further diagnostic info. On Cold start up it seems to be ok, and after its running for a minute or two is when the obvious misfire begins. That's when the engine starts shaking and the misfire is audible in the exhaust tone. I disconnected the VCM Muzzler and it made no difference as I expected.
 

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IN my experience, cold starts run richer mixtures which can mask timing/compression issues until the mixture leans out under closed loop. As you've ruled out ignition and can probably (?) rule out fuel, there's not more I could guess at--maybe the career mechanics can venture more-- without more diagnostic info. Do you have a digital scope or DVM to capture starter voltage during simple relative compression test (WOT cranking)? Or record audio of WOT cranking?
 

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Discussion Starter · #12 ·
I've got a 2012 with 152k miles on it that started shaking badly for my wife on Monday and she said it stalled when she came to a stop. It showed codes P0300 P0301 P0302 P0303. 7 months ago at, 145k miles, it threw the P0303 code and had an obviously oil fouled plug in #3. At that time I soaked all 6 cylinders with a little Marvel Mystery oil, installed new NGK plugs, installed new PCV Valve, and installed a VCM Muzzler.

I pulled the plugs out Monday and they looked very clean. Swapped coils from front to rear and the codes stayed the same. When I pull the plug off of each coil immediately after starting it cold, there is very little difference in idle for any and it is generally running smoothly. Once it's been running for about 2 minutes it starts shaking with an obvious misfire tone in the exhaust, and when pulling the plugs off the coils the idle varies a little for 1 & 2 in the rear, not at all for 3 in the rear, and drastically for all three front, 4, 5, & 6.
Tonight I took the following compression numbers:
1 - 144
2 - 132
3 - 140
4 - 165
5 - 172
6 - 167

Is this just the ring issue from the VCM and I need to re-ring the engine? Or is it possibly something cam/timing related? I think my next steps are to pull the accessory belt and timing covers and make sure everything is still lined up. Maybe do a leak down test? Looking for advice/input.

Thanks,
Keith
 

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Just my basic run down list can sometimes identify a problem. If you haven't already, I'd disable the VCM. I use S-VCM.
  • Disable the VCM
  • Air filter New/Clean
  • Clean MAF
  • Air intake tube leak free clamps tight
  • Spark plugs NGK Laser Iridiums
  • Spark plug tubes oil free, replace valve cover gaskets grommets and tube seals if oil is present. Replace plenum gasket if doing valve covers.
  • Coils oil free, replace swollen oil soaked boots.
  • Replace PCV
  • Replace EGR valve (last, high milage, with unexplained rough idle
  • Use Full synthetic 0w20 oil, no blends or extended performance oils
  • Use Top Tier 87 octane fuel or regularly use injector cleaner.
Hopefully it hasn't jumped time. It's worth checking as Slvr7 said.
 

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Discussion Starter · #15 ·
Just my basic run down list can sometimes identify a problem. If you haven't already, I'd disable the VCM. I use S-VCM.
  • Disable the VCM
  • Air filter New/Clean
  • Clean MAF
  • Air intake tube leak free clamps tight
  • Spark plugs NGK Laser Iridiums
  • Spark plug tubes oil free, replace valve cover gaskets grommets and tube seals if oil is present. Replace plenum gasket if doing valve covers.
  • Coils oil free, replace swollen oil soaked boots.
  • Replace PCV
  • Replace EGR valve (last, high milage, with unexplained rough idle
  • Use Full synthetic 0w20 oil, no blends or extended performance oils
  • Use Top Tier 87 octane fuel or regularly use injector cleaner.
Hopefully it hasn't jumped time. It's worth checking as Slvr7 said.


  • VCM was disabled 7k ago when it threw the P0303 code.
  • Air filter is clean, it was replaced 7k ago.
  • I could Clean the MAF, but that will not cause low compression on one bank or misfires on one bank. Right now it’s far enough apart I can’t start it and run it anyway.
  • Air intake tube was replaced in the last year or so because it cracked between one of the ribs. Both old and new were/are clean (no oil residue) and clamps were tight.
  • spark plugs were new NGK iridiums 7k ago. This is what they look like now

  • spark plug tubes were dry
  • coils were oil free and seals show no signs of swelling
  • pcv was replaced 7k ago
  • EGR valve was replaced a few years ago. I’d have to look at my records to see when.
  • last 120k miles of oil changes have been done every 5k miles with either Castrol Syntec or Mobil 1 0W20 and WIX or Honda Filters.
  • only ever get 92-93 octane, but no idea when the last is I ran a fuel system cleaner in it

Timing belt was replaced a little over 3 years ago but it looks like I did not replaced the tensioner. I’ve got over 20 years experience working on Subarus. The tensioner is almost identical to what Subaru used in the 90’s and I’ve tons of success reusing those when handled properly. Maybe that’s not the case here. I’ll be pulling it apart tomorrow to check timing marks.


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You can check crank and cam timing without taking anything apart. Just remove the acc serpentine so you can see the white tick mark on the crank PULLEY clearly. Then get a socket on the crank bolt and rotate CW until the crank mark lines up with arrow, pop the rubber cam cover plugs, grab a flashlight and a mirror so you can look at the cam marks perpendicular.

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If it was running fine prior, I'm bugged if it could be the timing off. Guess stranger things have happened.
A dirty MAF can cause lots of bad stuff.
 

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Have you ever cleaned the EGR passages in the intake manifold? I am assuming that the 2012 J35 has an EGR system similar to the earlier years. The passages get full of soot, and can trigger misfire codes.
 

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Discussion Starter · #20 ·
I'll try to address all the comments:
  • Valve clearances have never been checked
  • EGR passages haven't been cleaned but I thought the EGR was only on the front bank and my issues seem to be focused on the rear bank
  • Timing belts can jump. It happens often on manual shift cars when the engine is overrevved. Subaru motors have an extra belt guide that is only on the motors for manual cars for just the reason. In any case, it would run fine one second and then not the second after it jumped.

Most importantly I'm having a heck of a time seeing everything and getting alignment using the inspection holes on the cover, BUT I do believe the timing belt jumped. With the rear cam mark seemingly lined up, the front cam mark is a tooth or two before the mark, and the marks on the crank pulley are all after the pointer. I'm going to pull the covers off and inspect further later today.
 
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