Well after discovering from experience with my 4th Gen nothing but NGK plugs work with them, I decided to pull out the Denso Iridium plugs that the previous owner of my 5.5th gen had installed, because at anything under 2,200RPM with any gear except first and under light gas pedal pressure I would get a severe miss, especially cruising on the highway in 5th or 6th gear. With thanks to "KiLLeR2002SE"'s write up as a guide to removing the intake manifold I decided to thow in a set of the the original spec NGK PFR5G-11 Laser Platinums. Now I think the cause of all this was there is a cheaper NGK Platinum ( more of a mass marker generic hence the price difference and less Platinum coverage on the electrode) available for about a third of the price so I asked the guy to show me each to see if there was a physical difference and sure enough the original spec one's threads are much longer which positions the plug almost 1/2" deeper into the cylinder. Once I pulled out the Denso's they were also shorter! Put in the NGK's and the miss is gone! soooo smooth now. Installing them myself and saving the cost of the install helped me off set the extra cost of the orignal spec plugs and being the PIA it is to install the rear three plugs I thought Plats were way to go. Just thought I'd share this info.

 

Bro I wonder if this is the cause of my mis:
http://forums.maxima.org/showthread.php?t=453113
I have Denso Platinums in the Back, and Bosch Platinums in the front that I just put in last night to see if it was maybe a bad plug
My misfire is in CYL #6

 

could you measure the Denso Iridium for me please

 

Good info, thanks for the heads up.

 

Sure I'll try to post later today as I'm at work

 

Ok I just went over to Advance Auto, and put one of the Denso Platinum Plugs I pulled out next to the NGK PFR 5G-11 Laser Platinum, and they were the same size...
So thats not the reason why my car is misfiring so much.........

 

Did you check the depth from the lock washer at the base of the plug where the thread starts to the tip? Not the overall length.Thats where the difference in length was compared to the Generic NGK plats and my old Denso Iridiums, I didn't compare to Denso plats.

 

yes I did, I also checked if the actual tip came out further, and it didn't.
oh well....

 

Here's the pic to prove it:
The Denso (model IK16) measures 7/8" from the lock washer on the thread to the tip of the electrode where as the NGK is 1 1/4". Obviously there is a difference where the plugs sits in the cylinder.

 

That was definately not the plug they pulled out for me, the one that I saw was 7/8"
and it was the NGK laser platinum that was around $11 and he said it was the NGK PFR5G-11 on the phone before I went there

 

That is because someone simply installed the WRONG plugs in that car. The part number PLFR5A-11 has the L in it for a reason, it means the plugs are the Long style (26mm).
And I feel sorry for anyone who put's VQ35 plugs in their VQ30 (goodbye pistons).



There is no difference where the plug sits in the cylinder, the electrode sits in the same place for each engine. The difference is that the VQ35 has thicker water jackets and needs the longer plugs to reach through the head.

 

Ok so once again I am back at the same spot with my VQ30 engine: #6 cyl misfire and it's not the spark plug

 

Coil pack? Corroded coil plug?

edit: Nevermind, I found your other thread.