1994 Q45 spark plug change

[artandscience]

I changed out my plugs this past weekend. I expected it to be much more difficult given that the "book" calls for it to take four hours. My local dealership charges over $500 in labour so I thought I would do it myself.

I started on the left-hand bank (passenger side) first because I thought itwould be more difficult (given the limited working room for the rear-most cylinder -- #8 I believe). I noted that the last Infiniti mechanic hadn't put in the bottom rear-most allen head screw to secure the plastic shroud. Probably because of space constraints.

I photographed everything with a digital camera before proceeding and took a couple of photos along the way (available if anyone wants them).

The key I found, other than having an articulated ratchet head, mini torque wrench and lots of extensions, is to be patient (as always!) and when you remove the coils, just remove the two bolts holding the coils to the block (there are actually four you _can_ remove, but you only need to remove the two that secure the coil mount to the actual block).

Left hand side took about two hours (moving at a slow pace) and the right-hand side took maybe three. Probably because I lost a socket in the nether regions of the motor and took 1/2 hr to look for it.

I would say be careful removing the electrical connections. On a ten-year old car they get a bit fragile (some plastic was already fractured).

Clean the area underneath the shrouds before removing the spark plugs. Apply anti-seize to the spark plug threads before reinserting and start them by hand to avoid stripping the hole. Also, only use a reasonable amount offorce securing the coil bolts, remember that you are putting a steel bolt into an aluminum block -- use caution.

I used a mini torque-wrench to torque all the spark plugs down to a littleover the minimum. I would recommend it unless you do this frequently. Partly because its aluminum you're torquing into, partly because they have a compressible gasket on the plugs.

I used PFRG-11 plugs I believe, same as I took out of it.

The idle cleared right up and now I can no longer feel the car at idle - something I was missing for the last 5-7000 miles. I think they really mean that you should replace plugs at 50k, not the 60k I did.

Total cost: 8 plugs x $10/plug (approx), one Snap-on 8mm socket ($8) lost.

I would do it again. One of the easier "complex" jobs I've had on a car.

I cleaned my throttle body a couple of weeks ago. If I hadn't this would have been an idle time to do it while doing the plugs.

This is not really more difficult than putting a new set of brake pads and discs on your car. If you've done that, and you're cautious with a wrench (that aluminum thing again), you can do this.

cheers, Stefan

[elwesso]

Good writeup... Please email me the pictures and ill add them to my writeup on Q45.org, as well as the stuff you wrote there

Too bad you didnt get your plugs from me, i coulda saved you about $30

[DAEDALUS]

Which 2 bolts are you removing to get the coils off? 4 bolts in the coils. 2 go the head, and 2 go to a mounting plate, which itself has 2 bolts into the head. Don't see how you can get away with removing fewer than 4 bolts/coil regardless of where they come from.

Right/left convention is based on driver's point of view. Passenger side is right side. Important to know if you're ever ordering parts.

[elwesso]

Dae on the 94 there are only 2 bolts that hold the whole coil assy down on teh valve cover

One on the top left and bottom right, if memory serves. i only remember having to remove 2 when i did the plugs, and I think jesda's Q might have been the same way!

[DAEDALUS]

Ah, sorry. Bolts on opposing corners. Guess they sharpened their pencils and decided they could live with the extra vibrations. Coil failure still not common on the '94-'95.

[Q451990]

It also gives the techs. an excuse to put my 90 back together that way too. Grrr....

[DAEDALUS]

Makes me wonder if the 3-bolts I've seen on a few Qs are OK--still far better than 2 since it leaves a stable footprint. Wonder if the coils are the same basic design, not reinforced.

[artandscience]

I'll send the pictures off tonight. Do you want unreduced (2-4Mb) images or JPEGs (say, 150k max per).

Let me know.

S

[elwesso]

Resize them to like 1024x768