It's Tune Up Time!

[SuperDave456]

Well folks, it looks like it is that time.

2004 Nissan Xterra. 78,000 miles. Naturally aspirated V6.
I just had the timing belt, coolant pump, tensioner and all those bits that I didn't want to mess with replaced by my tech.

It runs well, this is the first major service that it has had.

My tech said something to the effect that the spark plug wires are going. I took a look and they are. Seems that sometime in the past they got to close to each other and they have burned themselves in a couple places. They have been straightened out and no codes have been thrown, but still. It has been over 8 years, and I feel that it is time to replace things.

From what I am reading elsewhere online.
It looks like this car came with Denso/NGK double Platinum's. Capable of 100,000 miles (at least the ones I have in other cars seem to go at least 100,000 before other things like wires start to go).

Should I go with Iridium's? Or just stick with the Plats?

I know about the funky 6th cylinder plug that requires a universal joint and 2 extensions on your ratchet to get to. Any other tricks that yall know about on this one?

Thanks again!

 

[SteveSRT8]

I have nothing platform specific for you, but I am amazed that you have not thrown a misfire code!

Be very cautious about deviating from the spec plug. Many vehicles do not tolerate experimentation well.

 

[SuperDave456]

I'm kind of shocked myself, no pun intended.

My wife drives this a couple times a week, it sees maybe 5,000 miles a year, and I pop the hood and check the oil once a month or so and fill the windshield washer fluid.

I hadn't thought about the age of the wires. Just the mileage. So I didn't think much of it.

I might just have to pull one of the plugs to see what is in there now. I'm finding conflicting information online.

 

[michaelluscher]

If memory serves me correctly, most '96 Nissans and up spec'd NGK Double Platnium plugs, DO NOT GAP THEM, THERE OK OUT OF BOX, So key lesson is NGK ONLY on [censored] engines of any brand IME, Double Platnium or better. Thats probably whats in there now.

 

[GC4lunch]

Originally Posted By: SuperDave456
Well folks, it looks like it is that time.
...
From what I am reading elsewhere online.
It looks like this car came with Denso/NGK double Platinum's. Capable of 100,000 miles (at least the ones I have in other cars seem to go at least 100,000 before other things like wires start to go).

Should I go with Iridium's? Or just stick with the Plats?

NGK has a FAQ that addresses that question directly:
Originally Posted By: NGK
Q: How much of a performance improvement can I expect from changing plugs?

A: A common misconception is that changing spark plugs will result in a large power increase. In most cases, removing even seriously worn out spark plugs will only result in very modest power gains, typically about 1-2% of total engine output. This could be even less for computer-controlled vehicles, primarily because most newer vehicles have more powerful ignition systems and the vehicle's computer can make adjustments so that vehicle operation seems smoother and more seamless.

Many people think that simply supplying more spark to the firing tip can and will combust more fuel. What they don't understand is that most newer cars' engines are so efficient that they are already burning all of the available fuel. Simply adding more spark voltage can't burn more fuel because there is no more fuel to burn.

When a stock or near-stock engine is given a fresh set of spark plugs, peak efficiency is restored. The power gains that come from this restored state of tune are usually minimal. Any company that tells you that their spark plug will provide significant gains in power in a stock or near-stock engine is making blanket statements that may not be supportable.

Here is the URL for the above quotation.

In terms of longevity, remember that every spark has two ends, one at the center electrode, and one at the ground. Some iridium plugs have iridium center electrodes, but merely nickel grounds; they will have shorter lives than iridium/iridium, iridium/platinum, or platinum/platinum plugs. If you got 78,000 good miles on that vehicle and engine with double platinums, there is no reason to think you would get any less from double platinum replacements.

 

[mechtech2]

Worn plugs with wider gaps can actually work BETTER.
[Up to a point]
Really worn will show a decrease.

 

[artificialist]

Originally Posted By: michaelluscher
If memory serves me correctly, most '96 Nissans and up spec'd NGK Double Platnium plugs, DO NOT GAP THEM, THERE OK OUT OF BOX, So key lesson is NGK ONLY on [censored] engines of any brand IME, Double Platnium or better. Thats probably whats in there now.


Some Japanese cars also have a Denso plug that is a correct match.

But don't use anything other than NGK or Denso in any Japanese car. You can't always get the engines to run right with other brands of spark plug.

 

[229]

I would replace with factory plugs and change the wires. This era of Nissans are having problems with premature failure of the ignition coils. No need in helping their demise.

 

[artificialist]

Originally Posted By: 229
I would replace with factory plugs and change the wires. This era of Nissans are having problems with premature failure of the ignition coils. No need in helping their demise.

That, plus I would replace the distributor cap and distributor rotor.

 

[GMBoy]

I've used Autolite's (either plats or XP Iridiums) in everything from Domestic to Japanese and NEVER had any issues or comebacks.

I have, however, had issues with Bosch Plats in 2 different vehicles so I never used them anymore.

 

[SuperDave456]

Yep, I need to do the wires here soon. Those are pretty close to giving up the ghost and going from a "should" into a "need".

The plugs aren't "Bad" yet. So I'm researching as to what I should do.

Double Platinum's are what I have seen in 2 Nissan documents regarding my engine and vehicle.

I don't expect performance increases with just new plugs. I'd just like to get another 8+ years or another 80+ thousand miles out of this.
And the Cap and Rotor are a given. Those are a cinch if I am doing the wires already.

 

[The Critic]

I've found that the Denso Long Life Iridiums last longer, and work better than the NGK Double Platinums on the Nissan VQ35 applications.

Denso SK16PR-L11 is the plug you want.

 

[yonyon]

I would recommend that while doing a tune-up on this truck you clean off the shutter wheel for the distributor pickup using compressed air. If you're replacing the rotor it's just two screws away. These tend to get dusty over time and when enough accumulates you end up with a misfire.