Also check this for pictures:
http://www.nwpengineering.com/VQ35DE...structions.pdf
http://www.nissanhelp.com/diy/maxima...eplacement.htm

I have not seen any posts regarding the spark plug debate so I will start it off.

In my old car (Saturn SL1) I replaced the spark plugs with the Bosch Plat 4's. I noticed a rather significant improvement in the power I was able to get. I know that the 04's use a double tipped plat. plug. I was wondering if anyone has replaced the plugs with other plugs, and if so has anyone tried the Bosch Plat 4's?

I was once told by a friend who worked on cars regularly that it is not a good idea to stray away from OEM plugs. It only causes more damage in the end. I was hoping to get your thoughts, and or any facts that may exist out there.

I also have the service manual and I find the instructions rather strange to change out the plugs. Do you really have to go through draining the coolant and the removing the MAF?! BTW I have not really looked under the hood yet to confirm these instructions, thought I would ask first. It may be easier for me to look under the hood

I Cannot Upload the PDF for everyone to see the actual pages.
Here is what the manual has printed:

REMOVAL
1. Remove the engine cover, using power tool.
2. Drain engine coolant. Refer to MA-14, "DRAINING ENGINE COOLANT" . *
3. Disconnect the mass air flow sensor electrical connector and remove the air cleaner assembly and air
intake tubes. Refer to EM-15, "Removal and Installation" .
4. Remove the intake manifold collector, gasket, and electric throttle control actuator. Refer to EM-17,
"Removal and Installation" .
5. Remove the six ignition coils.
CAUTION:
Do not shock it.
6. Remove the six spark plugs using a suitable tool.
● If replacing the spark plugs use the correct spark plug for
maximum performance. Refer to MA-18, "Changing Spark
Plugs (Platinum - Tipped Type)"

 

I didn't think you had to drain coolant.

 

If you look under the hood there is no sight of the spark plugs. I was showing a friend my motor a few weeks ago. He asked where are the plugs ? I had no idea and we couldn't find/see them ? I know they're under there somewhere ??

So the instructions may not be so strange, but removing the MAF and coolant part does seem odd. Sorry no advice on the plug type.

Bob

 

NGK PLFR5A-11

You do not ned to drain the coolant. The reason that is listed is because you have to remove the intake manifold which has a small coolant line running through the throttle body. You can simply disconnect those small lines and cap them off without any problems.

 

SR20DEN,
Thanks for the info. I figured that there would some lines running along that area that would leak if not taken care of properly. Does nissan normally use NGK's on their cars. I guess the only way to find out what plugs are in my car would be to take it apart and find out empirically.

As far as the coolant...I am guessing to use a hose clamp to prevent any leakage, right?

Also, I know that no one has gone 100k miles in a year, but when the time comes to change the plugs it sounds like there is a lot to take apart. Has anyone experimented yet?

Thanks again for the info SR20DEN

 

Just my 2 cents, by the time I have to change the spark plugs on this car.......I might not even be the owner any more. For a 2004 vehicle, the spark plugs, unless you are having a misfire, should not even be an issue. +4 Platinum tips do not have the best reputation either. NGK is a nice plug in my opinion.

 

Bosch does not make plugs for the VQ35 anyway so it is a non issue. Other than NGK the only other plug manufacturer making plugs for this engine that I know of is Denso.

The platinum plugs should be changed at about 40k miles for optimum conditions and no more than 60k for any conditions.


There are several paragraphs on this site that talk about changing the plugs but you just have to find them. It really isn't difficult to do. What I always do, and advise everyone else to do, is remove the upper manifold as one piece. Don't waste your time removing the throttle body or separating the elbow from the plenum.

 

i was planning on changing the spark plug to NGK IRIDIUM # LFR5AIX-11, is it going to make it any better? coz i installed ngk iridium to my other car honda accord '92 and it does make a lot diff in the power and fuel efficiency, but since my maxima is '05 and my honda is damn old im not too sure if i should change it or not.....HELP ANYONE? ANY SUGGESTIONS WILL B GREATLY APPRECIATED

 

I was going to change my plugs and when I saw all the items that had to removed, I changed my mind. I will wait for the 100,000 check-up

 

The problem is getting to rear 3 plugs here's a few "Do It Yourself" for the VQ3.5
http://home.nc.rr.com/acbradley/2002a.htm
http://www.greghome.com/Greg's%20Garage/2002MaxSE/SparkPlugReplacement.htm

 

I'd do 60k, 80-100k tends to have melted/rounded grounds

MSD recently released a box that does but you won't really notice a difference.

It would be a waste of time and money but meh

 

50k-60k is more realistic for a plug change. It only takes me about 35 mins to do a set. It's not difficult to do.

 

First of all how are you doing?

It doesn't take 35 min. on a 6th gen. Its going to take them 2 hours just to swap out my manifold cover.

The 3 plugs in the rear are hard to get out. There is a whole like of stuff to remove to get to the rear plugs.

 

holy crap guys... first off if you are an owner of a 6th gen max and haven't looked under the covers in your engine bay, I encourage you to do so.... look and learn.... appreciate and understand..... I have read this whole page and was really disappointed in the fact that some of you don't know exactly what it is your car is holding under the hood.... the possibilities are endless with this engine.... this is the new and very much improved nissan signature motor we have..... as far as spark plugs are concerned.... you aren't going to see them like you would in a honda because they have "plugs" we have "coilpacks".... they are the squarish looking things that go ontop of the sparkplug.... and you can upgrade them to get more spark.... very costly..... and yes you can get an MSD ignition system for this car but it is in my opinion pointless..... and as far as switching out your plugs..... you don't need to until your 100,000 mile mark.... <----this is what Nissan suggests...... I say do it at your 40,000 and change to NGK iridiums like I did..... they help out but not all that much.... at least not noticable..... the idea of iridium plugs is for the life not the spark.... they maintain their spark like any other platinumn plug but last forever..... I mean you will probably never have to change them again..... that's why they cost nearly 10-20 dollars a plug and you have to get 6 of them..... you can go on ebay and get a set of 6 for about 60 dollars..... extremely worth it.... but like I tell everyone shop around..... any questions about our engine pm me and I will answer to the best I can..... or call your nissan service department..... as far as replacing them it will take at least 1 hour for the mechanically inclined and up to 3 hours for the engine bay newbies..... good luck...... ohh and look under the damned hood....

 

Ok, 40 mins on a A34 because of the EGR.

 

I think they realized how easy they made it for 4th and 5th gens and decided to 'improve' the design. I started reading the write up and the first thing on there was to drain the coolant. I thought I clicked on the wrong write-up! Taking that upper part of the intake looks a little easier than doing the same job on a 4th gen. A little coolant drips out, but not a big deal.

I'd still do it myself if I do end up getting a 3.5.

 

So today I had the idea to change my spark plugs. I have done it twice on my 2000 SE Maxima which I traded in for my current car. I thought it was going to be a simple task, as long as my back was strong for the rear 3 plugs. WOW! I did the front 3 in a jiffy. However, after following 2 "How to's" for spark plugs, I was unable to remove the rear 3. Either my patience was thin, my hands are too big or it's a pain to remove, a HUGE PAIN. I was unable to remove the manifold, the 2 rear screws holding that thing in place were impossible to get to. I will now have to take it to the dealership to remove and replace my 3 rear plugs. I have the plugs. I hope I am not paying much for labor. However, this whole thing was frustrating. The rear plugs are now more difficult to remove. Those communists at the plant are hoping to help mechanics by making small tasks almost impossible. Anyway, I'll get off my soap box. Have a good weekend.

 

What this thread lacks is any good scientific reason to change the plugs "before their time" -- as defined by Nissan.

In the olden days of leaded gasoline and even in the early days of un-leaded gasoline -- the gasoline all had fairly high levels of sulfur content, the plugs were erroded by the lead and the sulfur. They needed to be replaced frequently (like 40 K miles or less).

Today gasoline is not only lead-free, but also ultra low sulfur. So spark plug life is substantially increased. Go with the Nissan recommended replacement schedule and save money (and your time if you do the work yourself). Your plugs will probably still be good when it comes time to follow the Nissan replacement schedule.

Thanks for the tips on doing the replacement -- when the time comes for me to do it.

 

I just checked with a shop in my area and its 12 dollars per plug and 2.5 hrs labor for a grand total of $308.80. I am glad that I changed the plugs when I polished the manifold.

 

Thanks this was very useful.

 

I know this thread was started in 2004, but....you can get a set of 6 NGK Iridium IX plugs for $40 now on eBay.

 

1. any aftermarket platinum or better plug will perform just fine, it does not have to be iridium, it does not have to be ngk, it does not matter.
2. yes, DO change your plugs every 80K no matter what they are made from and no matter what the manual tells you. Because you don't want to f..k with seized plug in the engine block or broken insulator, trust me on this. Also do not forget to apply anti-seize compound before dropping them in, some plugs already come with it, some do not.

 

Im at 80K, would you guys wait for 100K or what? engine runs #1....

 

No comments for # 1.
Completely agree with # 2.

 

just wanted to throw in that i changed the plugs in my brother's 04. the write up on here was great but it took us a few hours to get the job done.

he has 114k on his car and the plugs were ok.

 

I (and Nissan) agree. You don't need to change the plugs early. See my earlier post on this thread (#18) for the reasons why this is NOT needed. It is science, not hear-say -- and a waste of money and resources to change them early.

 

I didnt see any evidence based report to change them before 100k miles... only "i think you should"

 

Change your plugs every 100k. It's that simple.

 

NKG Platinum! Extra 5 HP!

 

Actually I prefer NKG Iridiums even better than platinum!

 

Do iridiums really give any benefit over platis or it's just hype (else than lasting longer)

 

May not be to you but for the dyno, it sure does.

 

show me graphs

 

Did you find any seized plug? I am at 117k (over due) and I will be changing them shortly with ngk platinum.

 

no seized plugs but physically getting to the plugs/coilpacks was a daunting challenge.

 

appreciate the links to the writeup on removing the manifold. Doesn't look like a quick job but still manageable for the do-it-yourself person

 

How? Once you have the collector off the plugs are right in front of you.

 

the front three bank are easy bc they are looking at you. the rear three are much more work bc you have to remove the im

 

100,000 mile mark.... <----this is what Nissan suggests

I will disagree with Nissan as I was told the same thing from the dealership when I took the car there...Had my mechanic take a look at mine around 88K miles...he said they are toast and should be changed. He said I will get better gas mileage too if I do. Hmm I'm getting 17 MPG now city. Now pay him $200 or do it myself? That is question now

After owning this car, what Nissan says you should really doublecheck seems they are about fixing and charging you $$$$$

 

the 100k mark is assuming you got a good engine and free from internal oil leaks.
it's very easy to change plugs. it's just time consuming if you have to remove everything on top to gain access to it. disconnect battery, pull coil 1, unscrew plug, put antiseize in new plug thread, screw it in with a torque wrench (do avoid stripping the head) or tighten it until resistance is felt, put little grease in the boot, install coil, repeat steps to other plugs, connect battery, and start it up.