Does anyone know how to access, inspect and change the
spark plugs in our G35s? This would be a great addition to
our DIY forum. A full explanation with pics would be great!

2003 TwBlue 5AT Sedan, sunroof,
Graphite Leather, splashguards, HKS exhaust,
14 wire Grounding kit, 350Z duct, Stillen CAI
Underbody rear diffusers, Drilled alum pedals

 

It is pretty easy, just remove the ignition coils and the plugs are beneath them

Infiniti Wrench

 

LOL Where are the ignition coils? Got pics?

2004.5 Coupe/5AT/Ivory/Everything but chin spoiler/Z Tube-Popcharger/Crawford V5 Plenum on the way

 

Look along the valve cover area, you will see them. Sorry man, i dont have any pictures. The coils dont look like your typical auto coil. You will see the top of them, they are kinda square looking

Infiniti Wrench

 

How do you remove the ignition coils? Do you just pull
upward on them? We need a pictorial on how to do this!
I guess it is easier to do than the transverse mounted
Maxima V6? The rear plugs on the Maxima must be "dealer
only"!

2003 TwBlue 5AT Sedan, sunroof,
Graphite Leather, splashguards, HKS exhaust,
14 wire Grounding kit, 350Z duct, Stillen CAI
Underbody rear diffusers, Drilled alum pedals

 

There are three coils on each side, two small screws hold the coils down, remove the screws and pull out, the plugs are down in the hole...

Infiniti Gearhead

 

we really need a DIY post for this topic.

I just changed my plugs to NGK Iridiums. Here's the procedure and tool list.

TOOLS:

6 NGK LFR6AIX-11 Iridium IX Sparkplugs (these are 1 heat range cooler than stock)
3/8" Rachet
3/8" long extension (at least ten inches)
10mm socket
16mm "deep" socket (or "sparkplug socket")
Magnetic pick up tool
3-prong grabber (optional, you'll need it if you don't have a "sparkplug socket")
Pliers

Most people would have these tools in their garage. The long extension is a must. The magnetic and pronged "pickup tools" make this much easier.


PROCEDURE:

1) DISCONNECT THE NEGATIVE BATTERY TERMINAL!
2) Remove the engine cover. it is 2 10mm nuts and 2 10mm bolts
3) Remove the intake tube. This should require the removal of (1) 10mm bolt and 2 hose clamps. Don't forget to disconnect the rubber breather tube; use pliers to loosen the clamp. Tne pull the rubber tube away from the intake pipe.
4) Let's start on the driver's side first.
5) There are 3 coils on each head. They are held in place with a single 10mm bolt. Underneath these coils are the sparkplugs.
6) to gain better access to the coils, you'll need to remove 3 10mm bolts which hold down an electrical harness just above the coils. All the bolts are easy to get to. You may have to push a couple hoses out of the way to get the back bolt though. Be care ful not to drop the bolts!!! The magnetic pick-up tool can be very helpful here!
7) After you have removed the bolts for the electrical harness, Disconnect the plugs going to the indiviual coils. There are 3 plugs to undo. They are snig, but they come off fairly easily with just your fingers. Remember which plug goes to which coil. That is extremely important!!!!
8) Now you have good access to the coils! Use the 10mm socket to remove the bolt from the coil. Once you have removed the bolt, the coil will pull straight up out of the head. This should be very easy to pullout.
9) You should be able to see the sparkplug in the hole. It is pretty far down there.
10) Use the 16mm socket with the extension to remove the plug. If you aren't using a sparkplug socket, you'll need to use a 3-prong, spring loaded pick-up tool. This tool makes plucking the plug out the head very easy. I'm sure you can come up with some other sort of tool to do the job, but that is what I used.
11) Replace the sparkplug with your new plug! Make sure not to crossthread or overtorque the plugs! Aluminum heads are easy to strip out!
12) relplace the coil, its bolt and plug it back in to the harness.
13) Repeat steps 8-11 for the other 2 cylinders!
14) Now, you have completed the driver's side of the engine. Don't forget to bolt the wiring harness back into position with its 3 10mm bolts.
15) You can also replace the intake tube at this time.
16) On to the passenger's side of the engine.
17) This side is slightly harder....only because some of the bolts are difficult to reach by hand.
18) I started by removing 2 10mm bolts which retain the wiring harness. I only removed the 2 bolts closest to the front and middle of the head. The rear bolt is not necessary to remove.
19) You will need to remove the rubber breather tune that runs from the valve cover to the intake manifold. Use the pliers to loosen the clamps; then, slide the tube off of the engine.
20) Now, you should be able to disconnect the electrical plugs from the coils. This is the same as on the driver's side.
21) The coil removal and plugs change is the same as described above. The only difference is that the back (toward firewall) coil bolt is difficult to get to with your fingers. Use the magnetic tool to remove and replace this bolt.
22) After repeating the procedure for all the cylinders, you should be done. Make sure to check that all the electrical connectors are snug and "clicked" tight.
23) Very important, you shouldn't have any extra bolts laying around!!!!
24) put the engine cover back on. Secure it with its 4 fasteners
25) reconnect the negative battery terminal.
26) YOU ARE DONE!!!!!

I think I remembered all the steps. This took me about an hour, going at a leisurely pace. Additionally, I was figuring it out as I went. With some motivation, you could probably do it in 1/2 an hour.

Have fun,

Andrew

 

what kind of results will going a step cooler or upgrading to these plugs show?

 

not sure......I just hate platinum plugs. THey last a long time....that is why the manufatcurers use them. They like to say that you can run on these plugs for 100,000 miles. The problem is that platinum plugs are one of the lowest performing plugs available.

In my 550RWHP Cobra, I used $1.00 autolite 764s Great permormance, but they need to be changed every so often.

These iridium plugs use a very fine wire to achieve a more concentrated arc.

I haven't driven the car yet, only idled it and revved it. It is idling lower now. 1 line lower on the tach (not sure how many rpms that is) and smooth.

I went with 1 heat range cooler because it is so damn hot in florida during the summer months. Having cooler plugs may not do anything for me now, but What The Hell! This engine seems to lose alot of power in the heat. I wonder if the engine computer is pulling timing due to "knock." BTW, is there a knock sensor on these cars? Finally, the cooler plugs will also be beneficial if I decide to add some liquid supercharging!"

 

The only reason to go with a colder plug is because your engine is creating significantly hotter cylinder-head or combustion chamber temperatures compared to stock. Extensive engine mods like forced induction or heavy NA engine work with high compression ratios will generate that added heat. So colder plugs are needed in those situations in order to draw away the added heat and regulate the temperature of the spark plugs firing tip. So don't think that just by adding colder plugs to a stock or mildly moded car will produce improvements. In fact if your plugs are too "cold" you will end up fouling your plugs in a much shorter period of time because the plugs aren't hot enough to burn off the carbon deposits.

Here's a pretty good article on spark plugs.

Click Here

 

u can also gap them a little bit more then what they're suppose to be

 

The way Infiniti says to change plugs...

REMOVAL
1. Remove engine cover with power tool. Refer to EM-18, "INTAKE MANIFOLD COLLECTOR" .
2. Remove ignition coil. Refer to EM-35, "IGNITION COIL" .
3. Remove spark plug using spark plug wrench (commercial service
tool).

 

wow, that's a whole lot easier than the huge, in-depth, step-by-step description that was listed above. thanks infiniti for all of your hard work to make it easy to undersand... that sounds so simple. only a 'power tool' and plug wrench... it's no wonder i'm going to stay with infiniti for my next car... it's great examples like those.
just like the window tint made a creaking noise in my door because the 'extremely tight tolerances that the cars are built with'... right... no rattles....
sorry. thanks jim for the laugh. i can always count on infiniti.
(i better watch the infiniti bashing on this website)

 

On page 50 of the Summer Issue of Sport Z Magazine is an article entitled "Adding Spark to the VQ" which covers how to change the VQ's spark plugs.

 

i just spoke to my mechanic today about changing the plugs. he said that it wont make any difference unless the car is running hot, or in hot temperatures. if your going FI then its a must b/c of the extra heat, but if your running mostly bolt ons, not gonna make a difference. he actually said it may even run worse...