Spark Plug question

[thescreensavers]

My G35 with the VQ35 engine is mostly stock except for a +2 timing advance

I am going to get new spark plugs now that I hit 60k so that I could check for a common oil pooling issue.

The stock plugs are

Stock heat range:
Platinum - PLFR5A-11

One step colder:
Platinum - PLFR6A-11

In the manual it says

Cold type spark plug is suitable when spark plug knock occurs with standard type spark plug under conditions
such as:
Extended highway driving
Frequent high engine revolution

I do sometimes get some knocking once in a while if I redline it, this started happening after the +2 advance.

I also live in South Florida where its hot most of the time.


Would I benefit from the One step colder plugs or should I keep with the stock stuff?

 

[Bartman39]

What fuel do you use...? A colder plug can help but fuel quality can do alot more... Another tweak is a slightly cooler thermostat which helps keep engine temps cooler which also helps with the knock or more like rattle that you are hearing...

 

[Eli]

I'd go ahead and try the cooler plugs. Just inspect them after like 1,000 miles to see how they're doing.

 

[Viperoni]

I'd go ahead and try the cooler plugs. Just inspect them after like 1,000 miles to see how they're doing.

QFT

Just don't use Bosch's or other shenanigans, NGK only.

 

[thescreensavers]

I'd go ahead and try the cooler plugs. Just inspect them after like 1,000 miles to see how they're doing.

alright, what am I looking for to "Inspect" them?

Thanks for the replies people.

 

[exdeath]

alright, what am I looking for to "Inspect" them?

Thanks for the replies people.

For heat range, looking for a band to be around the middle of the curve on the ground strap.

 

[Vette73]

To cold and the plugs will gum up as they don't get hot enough to clean. To hot and the plug will burn out the head.

But yea try to find a thermostat that is about 5degrees cooler (not to cool and the engine control system will not work correct) and make sure to run prem fuel all the time if not already.

 

[T2urtle]

your car is stock, even w/o the timing advance there are times where your ECU will advance it at +2. You just force it at 2 all the time.

I would run stock plugs. People often mistake simple mods that barely do anything other then the butt dyno as " i now need to adjust for the mod i just did"


if your car is knocking while redlining, MAYBE you shouldn't be redlining. Or how often do you redline to justify getting colder plugs to try to prevent it from knocking.

But its up to you, i'm +2 advance on stock spec plugs with other barely there mods and no issues with knocks. Even when i had to run 89 octane for like 2 days.

 

[zerocool84]

I wouldn't go one step colder at all with just that. Just get new plugs and adjust the gap until you get blow-out then back it up a little bit.

 

[Bartman39]

I wouldn't go one step colder at all with just that. Just get new plugs and adjust the gap until you get blow-out then back it up a little bit.

WTF is "blow-out"...? Thats a new one...?

 

[exdeath]

When the spark isnt strong enough to light under compression/boost either due to too much gap or not enough energy. Usually shows as breakup or sudden flat line or loss of power on a dyno.

Of course you've never heard of it with a diesel

 

[thescreensavers]

your car is stock, even w/o the timing advance there are times where your ECU will advance it at +2. You just force it at 2 all the time.

I would run stock plugs. People often mistake simple mods that barely do anything other then the butt dyno as " i now need to adjust for the mod i just did"


if your car is knocking while redlining, MAYBE you shouldn't be redlining. Or how often do you redline to justify getting colder plugs to try to prevent it from knocking.

But its up to you, i'm +2 advance on stock spec plugs with other barely there mods and no issues with knocks. Even when i had to run 89 octane for like 2 days.

I haven't noticed it in a bit, but even under load it might ping were I feel it hesitates for a split sec. This is right after the timing advance and it seems to not be doing it any more. I always run 91 or 93.

 

[Bartman39]

When the spark isnt strong enough to light under compression/boost either due to too much gap or not enough energy. Usually shows as breakup or sudden flat line or loss of power on a dyno.

Of course you've never heard of it with a diesel

Does that mean I should change the plugs in my diesel...?:biggrin:

Also I`m to guess its just a different term for a missfire...?

One nice thing about a diesel is most of the time just change the fuel filter and it fixes all kinds of issues...:thumbsup:

 

[exdeath]

Its a type of misfire technically I suppose but its called spark blow out when it's this particular problem unique to the plugs themselves and consistent. Generic misfires are usually random, affect a particular cylinder, attributed to shorts, mixture, coils etc.

Spark blow out is a very specific and easily identified issue not usually associated with "standard" misfires.

 

[Eli]

When inspecting them you're looking for carbon fouling; black deposits on the portion of the plug exposed to the combustion chamber.

On the opposite side of things, if the plugs are getting too hot, there will be white deposits. Or the inner ceramic will be glazed. Or the electrodes will melt.

Ideally, your plugs should be a nice tan color with no deposits. That means the heat range you're running is ideal for your driving conditions. If this is the case, then you need to look elsewhere to solve your pinging problems.

Which would probably be advisable anyway.

FWIW, high RPM detonation is the worst kind as it is hard to hear and very violent.

 

[Bartman39]

Spark blow out is a very specific and easily identified issue not usually associated with "standard" misfires.

Just never really heard the term and you would figure with todays very high energy ignition systems and platinum plugs you would`nt have that issue...? But on the other hand with todays watered down weak fuel (pump gas) and running boost of any kind or even just EFI oh and wonder about nitrous if it also causes this...?

Learn something everyday...:thumbsup: BTW very interesting info...

 

[brblx]

just put factory plugs in it. those cars hate aftermarket plugs. if you must tweak heat range, still at least buy some kind of nissan-branded plug with the same tip or an equivalent from their OE.

edit- i guess that's what you're talking about in the OP. if that is a factory PN (doesn't look like a nissan PN, can't remember what brand of plugs they use), then i say go ahead. i don't think it's going to hurt- or that you'll notice any difference.

 

[thescreensavers]

just put factory plugs in it. those cars hate aftermarket plugs. if you must tweak heat range, still at least buy some kind of nissan-branded plug with the same tip or an equivalent from their OE.

edit- i guess that's what you're talking about in the OP. if that is a factory PN (doesn't look like a nissan PN, can't remember what brand of plugs they use), then i say go ahead. i don't think it's going to hurt- or that you'll notice any difference.

Yes, Infiniti comes with NGK stock. These are the part numbers out of the manual.

I am leaning to stock plugs since my motor is stock pretty much, just an inquiry

Thanks for the help guys.