Hey I got an '03 Z and hit 35k and I do all the services on time as recomended and just curiouse when should I change the Spark plugs on my Z?

Is it like a civic where you can never change it? Or should I do it like NOW??

When I do change the plugs should I get Bosch platnium 4's? One prong or three or four prong??

 

you never change it on a civic?

 

Yeah, they are the special 1,000,000,000,000 mile spark plugs. I've heard of civic owners wearing out their cars, then taking the plugs and putting them in their new car. This process can be repeated several times and you can even hand the plugs down to your grandkids (heirloom sparkplugs)

Seriously, I don't mean to be a *****, but this must be in the manual

 

I would say that as long as the spark plugs are working there is no need to replace them. Just verify that they are all working and if so leave well enough alone. You can still replace them if you want but it would be a waste of money and time. Unlike some other things spark plugs usually last a pretty long time.

 

that's amazing. i change the spark plugs on my civic every 30,000 miles. but i don't know how long the Z spark plugs can last, but i think it should be long.

 

Well a lot of cars mfgs. will tell you that you don't have to replace your spark plugs until 100K. However, I replaced my stock Platinum spark plugs with NGK Iradiums about 6 years ago now and what a difference. Them darn things are $6 however. The car ran a lot smoother and I ran slightly better times at the track. I figure $50 for better plugs and smoother idle was worth it alone.

I figure I'll replace my spark plugs with Iradiums in my 350Z now. I just forgot how nice a improvement it was on my Firebird. Now that this has been brought up I'll change them in the next couple of days and see if I notice a improvement. I'll post back here if I get a chance to do this.
Below is the info I found on the NGK site.

NGK IRADIUMS = Iridium IX LFR5AIX-11 gap at .044

The Spark Plug Serious Enthusiasts Rely On

Iridium IX Spark Plugs are the most technologically advanced high performance plugs available. Featuring a 0.6 mm iridium center electrode tip, they offer superior ignitability without sacrificing durability. The tapered ground electrode increases flame kernel expansion, while the superior heat range design is ideally suited to the demands of high performance environments. Specially designed to meet the needs of serious enthusiasts, Iridium IX Spark Plugs offer outstanding acceleration, high fuel efficiency and long life. When you demand the most from your engine, rely on the proven performance of NGK Iridium IX Spark Plugs.

NGK's new Iridium IX is the personification of these qualities and takes premium performance spark plugs to a new level. A level that is expected from the world leader in spark plugs.

The future has never looked so good.

 

Keep in mind mecinoid that a lot of stuff like this is purely mental. You think there should be an improvement and you want there to be an improvement so your mind tends to believe that there actually is one when in reality there is often no difference at all. This applies to many of the more mild mods people do to their cars, like grounding kits for instance. There never has been any hard physical evidence to prove that they actually do anything for the car but yet everyone who installs them swears that it makes a difference.

 

Really, the Firebird did idle much better. They idle a bit rough from the factory with the .500 lift cam etc... So, I figured it wouldn't make a difference. The idle really smoothed out at idle however. I went to the dealership afterwords just to see if it was my car. I started three other cars and they were like I remembered it. I got into mine it was so much smoother I still didn't believe it. Mine still runs very smooth after six years. You don't see any shifter vibration. My emissions at idle are unbelievable. I think it might be burning the fuel more completely even at idle. Maybe just a minor difference in heat range between mfgs. I don't know. But it is nice.

This is what I hope to achieve on the 350Z. I'll try to take a video of the shifter in neutral before and after so you can see and maybe we can measure any difference that we might see. Hope it works as nice as it did on the Firebird.

The draw back on iradiums from what I have heard is you don't want to use them in NOS cars or FI cars. I don't know how much truth there is to this but it is something the motor builders were cautioning on LS1TECH.

 

I know the factory plugs are rated at 100K miles, but I blew a plug NA with a perfect tune at the track at around 51K miles. The grounding strap on cylinder number 5 had bent down eliminating the gap, and melting to the electrode. I had to limp it home on 5 cylinders. For about 1-2 month(s) before, I had felt my cars acceleration die down, it just didnt pull up top as hard as before, and my traps went from 106-107mph to a weaksauce 104, so it wasnt just in my head. I put in a set of NGK Iridium plugs and the car pulled good again. So for you mod'd, hell even stock Z's pull your plugs at 50K miles and look at them, mine looked like they were 10 years old. For $60 you might regain some lost power, and it only take 45 minutes (taking your time) to change the plugs.

 

Not true. Iridiums usually 1 step colder are actually the plug of choice for most FI owners. I know N20 guys are generally fine with Iridium as well, although copper works fine for them and is cheap. Your not supposed to use platinum plugs with N20....

 

What does your maintenance manual recommend?

 

Ah ..... Maybe that was it. I think you are right since most of the LS1's come stock with the platinum. They were all talking Platinum when I was telling them about the Iradiums. Thanks for clearing that up.

 

^^ No problem

BTW David I believe the maintenence manual suggests platinum plugs, as thats what we have stock. They were $108 from a local dealer, I bought much better Iridium plugs for $65 shipped, from www.forgedinternals.com fyi....

 

Update - Bought my Iridium plugs

NGK IRIDIUMS = Iridium IX LFR5AIX-11 gap at .044

They cost 52.xx shipped to my address in California.

I installed them today and it took about 75mins for the complete install.
I took my time and made sure that I didn't shock the coils taking them off the plugs. Those plugs are way down in there. However, they were easier than my Z31 plugs to install. You need a 16mm deep socket and at least one extension. I used two extensions to get up extend the wrench about the valve covers a bit. I also used a 18" nut / bolt grabber with a claw on the end of it. You know the ones you push a button on the end and the claw opens up. That tool allowed me to retract the spark plug and start the new one with the least amount of hassle.

So, now that they are all in I noticed that my car when cold revs up to 1500rpm for the first few minutes stepping down the thottle as it warms up. In the past the thottle would only go up to 1200rpms and would knock down to 900rpm when warmed up. Now it drops all the way down to 850rpm when warm and doesn't have a miss every 20 seconds or so. I like it. All the other Z I have listened to had this little miss from the factory after warm up. The Dealer said it is because of the emissions controls.

I think the fact that the Iridiums have a more intense kernel flame that it is completely burning all the gas at idle now. It revs smoothly all the way to 7000rpms now. Maybe the tachometer is lagging because I didn't get a fuel cut off at 6700rpm like I have in the past. Does this step up after you get over a couple thousand miles on it?

I did a preliminary mileage check on a short trip over to the Bay Area today on hwy 84. I got 32mpg. The most I ever got on that ride in the past was 28.5mpg. There is a lot of twists and hills on that route so I was really amazed. I keep it in 6th at 65mph except where it is 55mph and I left it in 6th when I could during that speed as well. I have to downshift a couple of times to slow for traffic etc.... However, I did take the 25mph turns at 55mph smoothly in 6th. This car handles great !!!

I think it is a fluke that the mileage was so good. I'm take a long trip later in the week and see if I can beat my overall best of 29.9mpg.

The funny thing is the shifter still wobbles a tad at idle, not once you add gas however. That part hasn't changed so I do not notice any SOTP differences in the cockpit. Just the slight miss condition has gone away and the car seems to operate better while warming up.

That's it for now. I think it is worth the $52 to me just to get rid of the annoying miss. I know no one else would care that much but little things like that drive me crazy.

 

Holy crap! 32mpg?!?! Is that even possible? That's 6mpg MORE than advertised.

 

That's downhill behind a semi with a tail wind...

 

Actually. The MSRP states. 17-23 around town and 22-30 on the freeway. 20/26 average.

Now I have the spoiler, splitter, iridium spark plugs, pop charger as mods don't forget.

Yes, that's what the gauge said 32mpg. Don't forget I have the stock 17's aired up to 35psi. Less rolling resistance. However, now I have about 250miles on this tankful now and have been in a lot of stop and go so she is down to 27.5mpg. I had to race around today since it was so nice out. I went up on my track and banged it around a bit. So, this tank doesn't count for my mileage test. That's on a half of a tank of gas. Woo-hoo!

I have to get her on a long stretch of over 100miles or so and I'll update you guys. Yeah, I am impressed too. Broken it in right shift easily, don't speed. Gradually acceleration..... I mean, I am going with the corolla traffic here folks. I think I can break at least the 30mpg and the way she is responding with the new plugs and all she is so much smoother; I really think I have a chance at 32mpg. I'll take a snap of the mileage gauge, fuel gauge and total miles so you can see when I do the test.

Heck, I did do the semi test however, and it could get close to 37mpg on a draft there at 58mph. He, he, he.

Maybe that G35 spoiler is helping with mileage as well as downforce. However, downforce generally means worse mileage. Who knows?

 

okay now iv got a question..... i read on the ngk site that cold plugs are the best if you race, mod, yada yada yada Sooo.. I do drive fast, i have bolt ons like full exhaust, intakes etc... Can i get these plugs and live in a cold state? Do you acually feel any difference right after install?.... you guys seem to be like yoda on this kinda stuff.... leme know, thanks josh

 

mxjosh - JMHO - I would get the standard range plug with your mods.

What I have notice since my install is this:

The car does idle smoother. It idles correctly now at 700rpm instead of 1000rpm like it did stock. Manual says 650-+50. So, the idle rpms are right on now and it doesn't load up like it was from the factory. You could even tell from the factory plugs that it wasn't burning completely. Just a tad of black soot on the plug edges. However, the center ceramic was still cream colored. That is what you want for the center.

Simply put - I no yoda, you don't want to change the heat range on the plug unless the motor isn't burning the mixture correctly. There is a lot of reason why this might happen. Generally, unless you are FI'd, if you are rich or lean you need to adjust something in the fuel maps to make it right not just change the plugs as a first choice.

If you are racing .... I mean at the track full on power all the time a cold plug might be a good idea. However, I would say that a colder than stock plug on the street would cause some fouling during stop and go traffic. You don't want that.

The colder plugs would be good if you NOS or FI to avoid detonation. If you are not getting detonation .... your probably better to stick with stock range.

Newest findings on mileage- My wife and I just came back from a pot holed twisty, speed varying drive to my folks house and back. Last time, with less traffic and even 72mph I received a 29.9mpg run by myself.

I am not sure if it was the plugs, extra weight(wife is only 95lbs), or the varying traffic but, my mileage for the 190mile R/T was only 28.6mpg this time. I did have to stop off the freeway twice..... That could have been just enough to drop the mileage a bit. I also was trying to adjust the speed to see if I could see the climb of mpg on the gauge. That could have screwed it up. However, for now, I honestly have to say the mileage went down from 29.9mpg to 28.6mpg @ an avg speed of 59mph. I was traveling on the freeway at 72mph most of the time. But, apparently there was enough "In Town Driving" to knock that down a bit.

I post again when I can make another long run. Hopefully, in the same conditions as I did when I made the 29.9mpg run. Not in Sunday evening traffic where I have to hit the brakes cause someone doesn't know how to merge, or cuts my off cause he/her want to go 20mph faster than everyone else, etc...

All in all I am happy. I just need a little more time with the plugs in there to see if I can prove any mileage gain or loss.

 

+1 for NGK Iridum plugs