A number of VQ40DE owners have installed the XTP plenum spacer for performance gains, but there is another huge benefit to this mod. Those that have tried have found that replacing spark plugs on the stock VQ40DE can be a bit of a challenge. With a little patience and a good assortment of universals and extensions, it can be done; it takes me about 45-minutes to do a set of plugs now having done it a couple of times. Since the last time I did it on my 06 Pathy, I have installed the XTP spacer and what a difference it makes when it comes to replacing the #1 and #3 coil packs and spark plugs! Even with my fat hands and chubby fingers, I can now reach under the upper plenum and get to the coil bolts and can get the #1 coil pack out without having to disassemble it! It still takes some creative extension and universal assembly, but not nearly as much as trying to do it without the plenum spacer. So, here are some picks of this project:
There are a number of choices for spark plugs. 2005-2006 used NGK Laser Platinum 6240. In 2007-2012, Nissan switched to the NGK Laser Iridium 93759. Both of these plugs are 105,000 mile interval plugs (the Laser Iridiums will actually last 120,000 miles, easily). Either will work in any year of the VQ40DE without any change in performance nor gas mileage. The Laser Platinums are less expensive. Some opt for the NGK Iridium IX 4469, which will also work just fine and cost even less than the Laser Platinums, but they are also only rated for around 60,000 miles. They are also a single tip, Iridium plug compared to the double-tipped Laser Iridium and Laser Platinum plugs. About two years ago, Nissan introduced their Ruthenium HX plugs. They are their "latest and greatest" plug, being marketed by NGK as "the highest performance and life expectancy of any aftermarket spark plug line." They are priced just shy of the cost of the Laser Platinum plugs (about $8/each at Rockauto). For the VQ40DE, the NGK Ruthenium HX part number is 96355. I also replaced two coil packs; I got genuine Hitachi (made in Japan) coils for $35 from Rockauto. Hitachi makes some of the OE coil packs for Nissan, along with Hanshin and Denso.
I use my Milwaukee 3/8" cordless ratchet for jobs like this! It's great for loosening bolts and spark plugs and running the plugs down once I finger-start them, however, I use my Snap-On 3/8" torque wrench to put the final tightening on the plugs at 18-20 lb-ft. If using new NGK plugs, do NOT use a lubricant on them, like anti-seize, as Nissan instructs not to. The plug is plated and lubing the threads could affect the torque on them. I use a 10MM 1/4" drive universal socket and extension to get the coil bolts out.
Yes! I can get my fat hands in there! Thanks, XTP plenum spacer!
If you disconnect the harness clip from the bracket, you can move the harness out of the way on the right bank and get to #5 coil a little easier.
Getting the harness connector off of the #1 coil pack can be a bit painstaking, but doable:
In this case, it's spark plug socket, short extension with electrical tape to lock them together, universal, long locking extension. When installing, if it comes apart, long, needle noise pliers can pull out the extension and socket.
The #1 coil pack can even fit through the opening in the upper plenum with a little maneuvering now with the XTP plenum spacer:
The left bank is easy to access. The #6 coil/plug in the back requires a little bit of thinking to get through the between the coolant and A/C line.
Yes, some Nissan techs actually do use torque wrenches!