DIY: Spark Plugs Change (HUGE Pics)
 

I figured since there wasn't a DIY for spark plug changes, I'd write one. It's not difficult at all, so nobody should have trouble.


level of difficulty:
1.25 out of 5 (5 being hardest)


approximate install time:
less than 45 min (longer if take optional steps)


tools:
ratchet with a long extension
10mm socket
5/8" or 16mm spark plug socket
torque wrench (both inches and feet would help)



Spark Plugs:

*Optional: If you do want to spend a little more time removing the plenum/intake duct to make the job easier, follow the directions as outlined in the Motordyne's installation guide.
http://motordyneengineering.com/manual.pdf

If you don't mind all the crap that's in the way of the spark plugs, then read on from here.

1.) First locate the coil packs. These will have a harness attached to them. Unhooking these harnesses make the job easier. Use the 10mm sockets to unbolt the bolt on the coilpacks. It helps if you have a long extension. Some of the coilpacks are hard to get to, as there are things in the way. These bracket-like things (gold in color) can also be removed with the same 10mm socket, if need be.

Here's an example of what the coilpack looks like.
Attachment 419730

Here's a picture where you can see the harness (gray plastic pieces the coilpack is hooked to).
Attachment 419731

2.) Remove the coil packs - you can just pull them out once the bolt is off.
[no pic]

3.) Insert the spark plug socket (5/8" or 16mm) with a quick release long extension in the hole the coilpack was in. It should be removed with little effort.
Attachment 419732
Attachment 419733

4.) Install the new spark plug and torque it down to 15-21 ft-lb (180-252 in-lb).
[no pic]

5.) Install the coil pack and torque the bolts down to 64-95 in-lb (5.33-7.2 ft-lb).
[no pic]

*If you removed the plenum and the intake duct, then follow the directions as outlined in the Motordyne's guide for re-installation.

What about orienting the spark plug so that it fires towards the exhaust valve is it? What is that procedure called? Adding shims of varying thickness to get it torqued down all facing a certain orientation...

Anyway, my question is where does one get the spark plug shims of varying thickness and how does one orient the spark plug (i.e. which way should it face)?

I think the process is called indexing. BTW, I really don't see a point in that. I'd assume a very very small difference, if at all, from all that work. If you still want to go ahead, then I suggest you look up "spark plug index" or something similar.

What spark plugs do you recommend on a 03 fully stock and what gap?

Thanks

For stock, use PLFR5A - 11. They come pre-gapped, so no need to touch them.

What about a moderatly modded NA car? I could use OEM plugs I'm sure but any performance gains to be had with other plugs? (Mods listed below). Thanks,
Fletch

The differences between different spark plugs are negligible, but I guess theoretically a hotter spark plug would yield that positive difference.

Hotter and Colder plugs:
 

Hotter plugs need to be used if the plugs can not maintain enough heat to burn off residue, as this will cause fouling.

Colder plugs are used if the plugs are not cooling down enough between each burn cycle, this will cause pre-ignition.

Plugs are a balancing act, it is best to stick with the recommendations of the manufacturer and use oem or aftermarket plugs specified for that application unless your car is heavily modded, in which case search these boards and talk to experts about your setup. Otherwise you are more likely to do harm than good.

Chris

I did some research on "indexing" when it came up before. It is not proven that there are any gains to indexing spark plugs, meaning, there is no dyno proof that I was able to find. Secondly, most of the newer plugs are "self indexing" with multiple grounding straps (most higher quality plugs that is, ie platinum etc.) The article I read, the guy did index his plugs, and in order to do so, he had to buy several sets, mark where the grounding strap was on a visible part of the plug, then put the plug in the motor. Only then could he tell if it was properly indexed. If it wasnt, he would pull it out, and try another. Sounds pretty spendy if you ask me, and for a minimal gain, if any.

good write up.

They used to sell indexing shims, so you could shim the plug a little this way and a little that way to get them straight. The thing about it is, back in the day (or if you have a car that still uses back in the day technology) you only had one valve. Most of the time, the valve would be on one side of the head and the plug stuck in some odd angle of the other, so indexing has its roots in some sound reasoning. You did not want your spark firing into a shrouded cylinder wall, especially considering your ignition systems ran on good old fashioned points and condensers systems.

These days the plugs are in the middle of the cylinder and with half of the roof taken by intake valves, the mixture will completely envelop the plug. This is one way cars today develop so much emissions restricted power per liter compared to the cars of yesterday.

Chris

If I remember correctly, I read somewhere that platinum plugs are not recommended, as the platinum plug can fall off into the cylinder. I read that quite some time ago when I bought new spark plugs.

As for spark plug types and gains... I doubt there's hardly any if at all. Just for my own reasons, I had to buy the NGK Iridium plugs. :-\

Nice short write up. It looks like a PITA to do but it's key to just moving the intake, strut bar, wiring, etc (which is not that difficult) out of the way to remove the coils. The job is also a bit easier if the coils are unpluged and removed while removing and replacing the plugs.

this may be a dumb question...

yes the HR engine is different, anyone do plugs on a HR yet? *doubtful*
would i be looking at the same places for the plugs? could i expect the same level of difficulty?

i got another 20k to go before i really have to worry about it though
if it's as easy as this... i cant wait! lol

doing the plugs on my 4th gen fbody..... oh man.... i dont want to go there again

Ok.. Nice DIY which led me to save $225 labor at the stealership.. But no fukin way u did this in 45 min... U must be one fast mofo.. :eekdance: It took me 2hrs..

This DIY should be almost/if not exactly the same as a DIY for changing plugs on a VQ35HR motor.

Hey guys,

quick question...

Last night I replaced my spark plugs and also installed a 5/16 iso spacer. I am trying to figure out where my problem might be. It was getting late and there is a possiblity I missed something but until I look at it today I just want some options :D

After I finished with the plugs and install I start the car and the revs up and then bogged down and stalled the first time. Ok learning curve then I start it again and it idles rough for a little bit and then bogs and stalles again. Really violent shake bog. So then I try the reseting TB and Idle air per the instructions.. Still no good.

I am posting here to see if there is anything the plugs and coilpacks can do to make this happen. I am talking with Tony now also.

I have the coilpacks in the right order: Left side 1,3,5 and right side 2,4,6. I first check this. I bought the pregapped plugs so no gapping was checked. They are all the right plugs.

One other thing is my buddy was taking the coolant hose off the Tb and some leaked out and possibly got onto a sensor on the back of the engine. The green clip in the back. I dried it off. But would that cause anything?

It could be a massive air leak I just don't know until I take it apart again and recheck everything(today)

Thanks a lot for the replys guys :D

Chris

I didn't want to start another thread up. But mods if you want me to I will :D

make sure you payed attention to the little rubber near the oil filler cap. if you dont pay attention and move it out of the way itll go between the spacer and the plennum and make a huge leak. thats what happened to me the first time i did it. symptoms sound fairly familiar. do a smoke test. should tell you where its leaking. most likely air leaking somewhere.

Hey guys thanks for the replies. I found the problem. I didn't pay attention to where the fuel pressure regulator was mounted(on the bottom of the bottom plenum.) I thought it fit between the Bot. plenum and the top with the spacer installed. It looked werid and didn't fit right. SO almost taking the car apart I decide to take it out between and guess what a hughe air leak. Those bolts weren't even tight :o

SO thanks for the help and the great thread on Spark plugs :D Helps a bunch :D

Chris

Every how many miles do I need to change spark plugs? I got 27k miles on my Z and never changed them. My car has a rough iddle and when I turn on the ac the revs go up a lil and get rougher, kinda unstable rev in neutral. WHAT CAN THE PROBLEM BE?

any mods on your car?

I think for stock plugs, you can leave them alone until 100k miles. If you've added some sort of FI to your car, it should be done more often.

hey guys i just installed my new spark plugs i used ngk PLFR5A - 11 plugs. and i didnt move the plenum or intake duct. i just got to the coil packs from the side. anyways when i start the car now i get a rough idle. almost like the cars camming? the plugs are pre gapped? but ima be checking them again to make sure. anyone have any advice on this problem thanks?

reply on plugs
 

i made a mistake when installing the plugs on the intake side i didnt plug the harness together right with the right coil pack.
On the intake side the last two harnesses for the coil pack i had switched.
Make sure that the middle harness goes to the coil pack in the rear and the last last extention goes to the middle
It sounds weird but it is so, that the wires dont get bunched up.....(Nissan made it look clean)

haha yep thats what it was i figured it out yesterday. doh.. hehe thanks anyways man

Now what kind of plugs are good. I've heard alot about NGK Iridium. I went to autozone and they had 2 kinds, the NGK iridium or autolite double platinum. How are the autolite plugs? does anyone know?

Just get copper: NKG LFR5A-11. They don't last as long, but they do conduct a better spark. And they're less expensive.

NGK. :)

Depending on your set up, a colder spark plug may be better. Again depending on your set up, a hotter or the regular (recommended) may be better.

If you're N/A and will drive in all normal conditions, the recommended spark plug is your best bet. NGK seems to be the popular brand and their prices are good. Copper ones do conduct a better spark, but iridium and platinums are also good and will last you a lot longer than copper ones.

i thought jeremy tibbs said copper was better for the juice:dunno:

Yeah, that's what he told me as well.

Copper is better. I was just saying that Iridiums will last longer. I have copper plugs in mine.

Ah, I only read the last post lol. I agree.

Come on, guys. My Z's bottle-fed. Do you really think I wouldn't know that little fact? :) You give me too little credit.

ok i have a question, generally on spark plugs

just yesterday, i was in my car and i turned the key and the car didnt turn on. you can hear it turning, but it never ignited. Is the spark plug the only possible reason for this? Or might something else be the cause of this? If the spark plug is the only possible reason, then im gonna change mine. Thanks alot

anybody tried using the pulstar plasma plugs on their z yet?

The dealer said the stock plugs were good for 100k miles.

So does the coil assembly have to be replaced at certain intervals?

The coils get replaced when they die. Theres no schedule for them.

I wanted to know if anyone has used the e3 sparkplugs? or opinion on them, brother told me to get them because he saw on horsepower tv that it helps car. I have my car with bolts on and I just want ngk iridiums.

ngk iridium is a much better plug, ive never had a problem with them..buddy of mine just put the e3 plugs in his turbo pt cruiser and burned one up within a few months, melted it i guess from what i heard

anyone every figure out the idle thing? the idle is def different now, feels like a misfire but i have no cel yet, so idk. help?

no idea what idle thing u are talking about here..but sounds like u did your own plugs and didnt clip all the clips back together right or mixed them up or just didnt do it correctly, pull and do again correct

changed plugs many a times. did one at a time, no mix ups there. everything is clipped tightly.

and im refering to a rough-ish idle. well not really rough, but it feels like a misfire as stated earlier

idk sounds like what my car did when i changed my plugs and didnt have one of the clips in all the way...clipped it in and problem was solved..

i just finished putting my iradium spark plugs, very easy to do. Not really a pain. You just have to remove some harness brackets to make some room for the coils to come out. Don't get discouraged :)

p.s. took me less than 1.5 hours

took me two days,,, sun got too hot,,, as hard as I tried I had the middle and rear plug on the left bank backwards, I paniced and called my son. he's a bmw tec. wow three mins he had it figured out. Can't beat a man at his own trade. But now I know why he dont wanna do **** on cars when he gets off work..

I just changed mine today car is a 05 at with 48k car had oil on threading and some on the plug.What does this mean?

Its normal, just means you have a leak in valve cover.. You could replace it if you wanted to.. They are 200 bucks a pop though... :icon27:

ok i have an 04 with 53k miles..im in the process of changing my spark plugs and rightnow when i took off the spark plugs from i believe its cylinder #4&#6 which is on the drivers side..the spark plugs were covered in oil..now i know this isnt good but i dont know how bad this can be??? can it just be the seals?

use the search theres a bunch of information on this, the seals cannot just be replaced, you must replace the valve covers i beleive, like i said search it...put new plugs in and deal with it, is that the first time the plugs ever been changed?

most likely you won't gain any hp or anything (i could be wronge)

but indexing is mostly used in engines that have such tight valve clearence and piston pop up that you would turn the plug away from the intake valves so they would not contact the plug when the valves are opening.

just did mine... for no reason really... other than a desire to do it... and per your torque specs...

DAMN!!! 65-90ft.lbs on the bolt that holds the coil pack on??? i dont even torque my wheels to 90... so i went with 65 and still got to sheepish to torque that hard on a 10MM bolt. so i backed off of it... i'll be damned if i'm snapping a bolt.

20ft.lbs was good though, just enough where you can feel the crush washer was flushed out and then tightened properly... good job. :thumbup2: