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Discussion Starter #1 (Edited)
Hey guys,

Have a 2006 Armada with 155k on it. Pulled a plug to check them a couple weeks ago and noticed that whoever had the truck before me didn't have the stock NGK iridium plug PLFR5A-11. They were also looking pretty bad so I decided to get some PLFR5A-11 and installed them last week. While I was doing it one of my coils came apart when pulling it, I believe they are meant to come apart and was able to get it back together. So new plugs and put coils back on, on my drive home the first stop light I hit I noticed that the engine was skipping a cylinder not consistently but enough to notice it. Ran perfectly fine when moving throughout the entire power-band except when I would stop at a light and was in that 500 rpm idle range. Every once in a while it would miss and you could see the tach drop to 400 for a second. I figured it was probably the coil that came apart, decided just to buy a new coil and install. Unfortunately this hasn't solved my problem.

Fast forward to this week, problem is still happening only at idle and in gear. Finally threw a code this morning and got the P0300 multiple misfire code. Any ideas?
 

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Where did you get the plugs from?
Just as a friendly FYI, the PLFR5A11 are Platinum plugs, not Iridium. (PLFR5A11 are the correct plugs though for '06)

Did you blow the tubes out with compressed air before you pulled the plugs to get any possible debris out of them before installing the new plugs?

Also, what brand coil pack did you go with?
 

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I would think that coil would be fine from O'reilly.

Again, did you blow out your tubes before removing the old plugs? There's probably not debris in them, but it is good practice to do it.

As for the plugs "platinum" is right in the name. I don't know if the "IR" is supposed to denote Iridium. I am actually in the process of changing mine right now. As ironic as it may be, I'm pulling out PLFR5A11's. There's no "IR" on them, just "R", but they are 8 years old. I am putting in DILFR5A11's, which are Iridium.

I saw Staple's comment above about possibly having coils switched... I can tell you that it would be near impossible to do that as the way the wires are bundled in the harness, you can really only go to the tube they are supposed to go to.

Your PLFR5A11's should be gapped at .044. I would pull a couple of the easier ones to get to and double-check the gap. Platinums and Iridiums are pre-grapped from the factory, but worth checking since you are getting DTC.

And then over on this thread we were just discussing fake/knock-off plugs...

 

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Discussion Starter #6
Don't mean to offend but did you maybe mix up the coils on two cylinders? If not, I'd test the coils and plug together - instructions here - start on page 326
No offense taken at all, I'm here for help and am not a self proclaimed know it all. I very well could have switch coils on 2 of the cylinders, when I pulled them I did it 4 at a time from left side the right side. They're all the same coils though right? Guess I don't really see how switching the coils around would cause a misfire? Figured I may have damaged the one coil when it came apart, so I replaced that coil with a brand new one.

Appreciate the info on testing the coils and plug together, honestly looks like I may be in over my head:oops:
 

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Discussion Starter #7
I would think that coil would be fine from O'reilly.

Again, did you blow out your tubes before removing the old plugs? There's probably not debris in them, but it is good practice to do it.

As for the plugs "platinum" is right in the name. I don't know if the "IR" is supposed to denote Iridium. I am actually in the process of changing mine right now. As ironic as it may be, I'm pulling out PLFR5A11's. There's no "IR" on them, just "R", but they are 8 years old. I am putting in DILFR5A11's, which are Iridium.

I saw Staple's comment above about possibly having coils switched... I can tell you that it would be near impossible to do that as the way the wires are bundled, you can really only go to the tube they are supposed to go to.

Your PLFR5A11's should be gapped at .044. I would pull a couple of the easier ones to get to and double-check the gap. Platinums and Iridiums are pre-grapped from the factory, but worth checking since you are getting DTC.

And then over on this thread we were just discussing fake/knock-off plugs...

I did not blow out the tubes, probably should have.

I'm guessing you should not put the DILFR5A11's in a 2006? Honestly thinking about buying 8 new plugs and putting them in vs checking each one in the coil. If that solves it I simply send the other plugs back to seller on Amazon. Will check gap tomorrow evening, gotta fix my damn washing machine tonight!

I see what you're talking about with the coils not easily being switched now, however I'm not ruling it out.

Interesting thread about the knock-off's. Definitely going to pull a couple tomorrow and compare them to the picture of the fake. Something about the outside of the box just seemed off to me...
 

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Don't go buying new plugs yet. There's a few basic things to check yet. I'm putting a picture together for you... give me a few minutes and I will post that after this.

But anyway, from NGK's site, here are your options for the '06. You can click the pic to fullsize it.
48325


So for the basics... again, check the gap on one or two of those.

But also, did you happen to remove any hoses so you had room to work, or possibly loosened them accidentally? There are 4 hoses (PCV and vacuum) (so obviously 8 ends to check) and I marked those ends on this pic.

Just make sure you didn't happen to pull any of these loose. You can click the pic to fullsize it.

48326
 

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I wouldn't buy new stuff just yet. You were messing with the cylinders and now you have a cylinder code - probably something simple. Another bad coil, loose coil, bad plug, loose connection, maybe a wire broke, harness wasn't plugged in all the way, etc.

What I meant by switch coils was maybe you put the #2 coil on the #4 spark plug. That is something simple that could happen doing the work you did. Either you did or didn't, easy to check.

As far as testing the coils and plugs it is no harder than what you just did. To sum up the manual -

- Pull the fuel pump fuse, start it and let it stall out. Crank a couple times to make sure. This just allows you to crank the engine in the next steps without actually starting the truck, otherwise you be starting and stopping it a bunch - and running it with a plug out.

- Pull a coil and a spark plug out. While still out, put the plug back in the coil and hold that unit (with a tool) with the tip of the plug 1/2" from a grounded piece of metal under the hood.

- Have someone crank the engine and see if you get a good spark.

That's it. Put the fuel pump fuse back in after you've done all 8.

What that does is check each coil/plug combo to see if it works. If one set is bad then you are down to the coil or the plug. You may also be able to test the resistance of the coils but I don't know those specs.

If they are all good then either you have an intermittent problem there (which is why intermittent / hard to reproduce problems are so hard to fix) or the problem is elsewhere - I'd look at fuel supply next.

Good luck
 

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- Pull the fuel pump fuse,
That's in your IPDM - 7th fuse (15amp) from the left...

48327


Oh and for the next time you buy new plugs, a great place to get them online is Rockauto.
 

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Definitely going to pull a couple tomorrow and compare them to the picture of the fake. Something about the outside of the box just seemed off to me...
You could also take one to your local auto parts store and compare it to one of theirs.

But since you mentioned you feel there is something off about the box, I took some pics for you to compare if you still have the boxes. If you still have them, let me know and I'll post the pics.

I've been doing some further reading on the fakes. I would try to validate that the ones you have are indeed authentic or fake. I think you could even call NGK tech support and cross reference the batch numbers stamped into the metal where the drive socket engages the plug.

Customer Service
1-877-473-6767, prompt #1
hours: 8:30am – 5:00pm
Monday-Friday EST

Technical Support
1-877-473-6767, prompt #2
hours: 8:30am – 7:00pm
Monday-Friday EST

So I am still not saying you have fakes as P0300 can be other things, but some of the posts I've come across seem similar to what you describe:

ugh..same happened to me. Bought 8 Nissan NGK spark plugs on ebay for $60 shipped..I have the 5.6L and now it's misfiring at idle. Barely using the suv til I can install new genuine ones. I ordered 8 new spark plugs from courtesy Nissan for $140..the counterfeit really look like the original ones I pulled from the engine though. One thing that caught my attention was the gap was all over the place: from 0.020 to 0.040. The OEM ones I pulled from the engine were all 0.035 to 0.038.

And...

got my replacement from Courtesy Nissan and installed them tonight. All 8 of them had the exact same gap 0.037 ish which is about the gap that was on the oem ones I removed with 120K on them.

The counterfeits I pulled had various gaps: 3 were 0.020, 3 were 0.025 and 2 were 0.030 ish. I also noticed the lower electrode had a wider base on the counterfeits as well as a different font on the side.

SUV seems to idle better at about 750 rpm vs 500 rpm with counterfeits. I was getting lots of misfires at 500 rpm.
I haven't felt misfires at idle so far in my test drive tonight. time will tell.
 

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NGK, Denso, Bosch... pretty much any manufacturer that has a fine tipped electrode on the spark plug (platinum, iridium, etc.) are manufactured pre-gapped already. You can easily damage the electrode by trying to gap these plugs.
 

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Discussion Starter #13
You could also take one to your local auto parts store and compare it to one of theirs.

But since you mentioned you feel there is something off about the box, I took some pics for you to compare if you still have the boxes. If you still have them, let me know and I'll post the pics.

I've been doing some further reading on the fakes. I would try to validate that the ones you have are indeed authentic or fake. I think you could even call NGK tech support and cross reference the batch numbers stamped into the metal where the drive socket engages the plug.

Customer Service
1-877-473-6767, prompt #1
hours: 8:30am – 5:00pm
Monday-Friday EST

Technical Support
1-877-473-6767, prompt #2
hours: 8:30am – 7:00pm
Monday-Friday EST

So I am still not saying you have fakes as P0300 can be other things, but some of the posts I've come across seem similar to what you describe:

ugh..same happened to me. Bought 8 Nissan NGK spark plugs on ebay for $60 shipped..I have the 5.6L and now it's misfiring at idle. Barely using the suv til I can install new genuine ones. I ordered 8 new spark plugs from courtesy Nissan for $140..the counterfeit really look like the original ones I pulled from the engine though. One thing that caught my attention was the gap was all over the place: from 0.020 to 0.040. The OEM ones I pulled from the engine were all 0.035 to 0.038.

And...

got my replacement from Courtesy Nissan and installed them tonight. All 8 of them had the exact same gap 0.037 ish which is about the gap that was on the oem ones I removed with 120K on them.

The counterfeits I pulled had various gaps: 3 were 0.020, 3 were 0.025 and 2 were 0.030 ish. I also noticed the lower electrode had a wider base on the counterfeits as well as a different font on the side.

SUV seems to idle better at about 750 rpm vs 500 rpm with counterfeits. I was getting lots of misfires at 500 rpm.
I haven't felt misfires at idle so far in my test drive tonight. time will tell.
Compared what I received from Amazon to a plug at O'Reilly's this morning before work. There was a noticeable difference. Leaning toward getting some bunk plug at this point. Gonna double check everything tonight after work and likely replace the plugs. Hoping this resolves the issue.

I really appreciate everyone's help on here, what a great community! Hoping to keep this truck for many many more years!
 

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Compared what I received from Amazon to a plug at O'Reilly's this morning before work. There was a noticeable difference. Leaning toward getting some bunk plug at this point. Gonna double check everything tonight after work and likely replace the plugs. Hoping this resolves the issue.

I really appreciate everyone's help on here, what a great community! Hoping to keep this truck for many many more years!
Excellent. Let us know how it turns out. Hopefully it is just those plugs.
Did you compare like-for-like? ie - PLFR5A11 --> PLFR5A11

Sucks you have to get back in there and do them all again. Cylinder 8 on bank 2 ain't no fun. My ribs are still sore from leaning back in there to get it yesterday.

I'd still stick with putting NGK's in there. Just be sure to get them from a reliable source such as an auto parts store or Rockauto.com (best prices) or CourtesyNissan.com or NissanPartsDeal.com, etc

BTW, don't put antisieze on the NGK plug threads. They advise against it as they already have some special coating on them.
 

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Discussion Starter #15
Excellent. Let us know how it turns out. Hopefully it is just those plugs.

Sucks you have to get back in there and do them all again. Cylinder 8 on bank 2 ain't no fun. My ribs are still sore from leaning back in there to get it.

BTW, don't put antisieze on the NGK plug threads. They advise against it as they already have some special coating on them.
Lol I hear ya, my ribs just got done healing up from last week:cry:
 

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Yeah, that is the same one I used, along with 2 other swivel adapters at the same time.
Love the magnetic plug socket.

It also helped to remove the IPDM cover for some more wiggle/viewing room.
 

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Discussion Starter #18
Alright guys, first off I appreciate all the help! Replaced the plugs with one's from O'Reilly's and that did the trick. The one's I bought off Amazon we terribly gaped and I suspect fake NGK's. First off I feel pretty stupid for not checking the gap before I put them in, didn't even need a tool to know these were way off!
48338


As tchjts1 was pointing out, the thread is much different on the left plug bought via Amazon vs. the right plug bought from the auto store. Tips of the plugs are different as well but mostly that gap is just terrible.

Special thanks to tchjts1 for all his help and recommendations on other things to check while I was under the hood. What a great community this is!

Let this be a warning to everyone, don't bother saving the $40 for some bunk plugs off Amazon. It's not worth the extra hassle.

Hoping to get my money back from Amazon after sending these POS's back.
 

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Glad you got it worked out!
Definitely a good lesson.

It was armadaY62 that pointed out the possibility of fakes a few days ago over on this thread, otherwise I was going to probably buy a set of cheap ones myself -

 

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Seems strange to me that you would get fakes sold by NKG on Amazon. I bought these for my 06, also sold by NKG, and they were / have been fine.

Found this on NKG website for those that come here in the future.
 
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