DIY Project - Replacing Spark Plugs on a Nissan Pathfinder or Infiniti QX4 with VQ35DE Engine

Well I hope this helps. If anyone has any questions, shoot me a PM or an email at tiage46m3 [at] gmail [dotcom].

pwnin, sticky!

Agreed! This is an awesome writeup....I was waiting for someone to do one so I have something to go off of when I decide to change plugs....way to go dude!!

good job

nice, I'll be tackling plugs/coils/maf/and cleaning throttle body this weekend. Thanks for the write up and pics!

No problem! Glad someone can actually use it.

Dude this is awesome, nice work! Post a link in the "How To:" sticky at the top of the forum.

+1
in for sticky!

Great writeup. Only thing different I would add is if you can't get the screws to remove the TPS on the Throttle Body, don't try too hard 'cause they will strip. I removed the throttle body (the 4 bolts, but left the coolant lines hooked up) so that it would be out of the way for plug access.

Why did you say its not necessary to gap the plugs?

They come pregapped perfectly

Great Writeup--can you do one for the 3.3 now?

Never..since I don't own a 3.3

They should be similar.. not that difficult to do.

Taking pictures of the DIY process was harder than the work itself.

Just did this. Engine was misfiring for 6 miles until we could get to a laptop (I have a USB OBD2 scanner), ignition coil pack #4 wasn't plugged in all the way (was throwing P1320 and the cylinder 4 misfire code, so I knew it had to be a coil). Oops. It didn't help that we had to go to Sears to get a lengthy extension for our ratchet (using 4 smaller ones chained together was not very safe) at 4PM after waiting an hour for a buddy to drive us there. We then spent another 4 hours swapping out the spark plugs; it took us so long I guess because we were having some difficulty getting the throttle body out of the way enough to get to plug #4. We did not use a torque wrench to torque the spark plugs (just hand tight and a bit after that) or the ignition coils. Looking back, I'm not sure why the hell it took so long. Reassembly probably took an hour and a half, though. My old plugs still looked quite serviceable, no carbon or oil build up. They probably could've went for another 50k miles without a hitch, but since I was this far and had the plugs might as well replace 'em. Mileage was 120,997 before changing. Not sure whether spark plugs were previously replaced.

Again, the TB does not need to be removed...

kkamakasi wrote:Again, the TB does not need to be removed...

We were attempting to loctite the power valve screws but we somehow managed to strip one of the bolts, so we gave up on that till I buy a replacement bolt, so the TB would've needed to come off for that too. We just moved the TB out of the way enough to access the plug in the end. And I guess we're dumbasses for not reading the guide more closely to see that removing the TB wasn't required, but like I said, removing the upper intake manifold was required for the PV screws and once we gave up on that we just decided to finish the plugs, and didn't refer to the guide again.

Well I feel really dumb. I just found the maintenance record for spark plugs. They were done by Nissan at 101k. I just replaced 20k old spark plugs that last for 105k. Great, waste of money and time.

Well look at the bright side. Now you won't ever wonder and now you know they
Were done properly. I have six new plugs to go in. Getting ready to check the power valves at the same time. Once this is done I'll have done all I can to keep this ga hog going.

Towncivilian wrote:Well I feel really dumb. I just found the maintenance record for spark plugs. They were done by Nissan at 101k. I just replaced 20k old spark plugs that last for 105k. Great, waste of money and time.

Just put the "old" ones in the boxes the new ones came in, and tuck them away in the garage somewhere. Then when your odometer hits 220k -- and you know it will -- you can just pop them in and run on those plugs until the odo hits 300k.

Densetsu wrote:

Towncivilian wrote:Well I feel really dumb. I just found the maintenance record for spark plugs. They were done by Nissan at 101k. I just replaced 20k old spark plugs that last for 105k. Great, waste of money and time.

Just put the "old" ones in the boxes the new ones came in, and tuck them away in the garage somewhere. Then when your odometer hits 220k -- and you know it will -- you can just pop them in and run on those plugs until the odo hits 300k.

We threw the old ones out.

Just replaced the plugs on my '04. Replaced the first four plugs within 50 mins, but when I was bolting the front passenger coil pack back on, the bolt head sheared right off. The bolt was going in fine and the head was about 1/8" from being seated on the coil pack; but then it started squeaking, and within four cautious quarter-turns with a socket wrench, it snapped right off, flush.

My brother and my dad (both experienced pipefitters) couldn't extract the bolt, so they drilled out the bolt and tapped a new hole for a slightly larger bolt. I'm really glad that I chose to drive out to my parents to do this, and that my brother was out there too, because I'm not skilled in this area at all. The new bolt bolted in just fine. I'm kinda paranoid about it, but realistically there's almost no force pushing the coil up and out, so all should be good.

The whole process took five hours, but other than the broken bolt, all went well. Just typical "why the hell do they stuff all these hoses and brackets and wires in here so tightly" frustration. The plugs were 141,000km / 7 years old, and one plug was significantly worn down more than the other five; hopefully this will solve my hard starts in the cold mornings.

Just did this, and when I was taking the last coil pack out (passenger side, closest to cabin), the top portion popped off the rubber part still in the "hole"!

I used needle nosed pliers to yank it out, re-attached it and no problem.

Good write-up, made me realise I'm missing a couple of screws...

Added to the How-To sticky, great guide!

I was bolting the front passenger coil pack back on, the bolt head sheared right off.

I am scared of breaking the bolt head while removing it. That would be nearly catastrophic. Do you think carefully spraying a bit of WD-40 on the bolt (without getting on coil pack) will help?

Needless to say I am very very disappointed in Nissan's choice of bolt and screw materials.

PB Blaster would work better than WD-40, and has a thinner spray pattern so it'll be easier not to overspray onto the coil pack.

seriously dude.....awesome thank you!

Thanks, I just use your guide to replace the #4 ignition coil which went bad.

Thanks for the write up. Good work. One thing I wanted to comment on is about the black sensor thing which you mentioned. That thing is Idle Air Control and it is pretty expensive (around 300dollars) to be exact. So be careful with that part folks. Good luck. I did mine and it was fun. Thanks again for the write up.

Hi guys! after got everything done as on pictures got problem with a car. While it's cold idling pretty ok but when engine is hot it has backfires especially high frequency when transmission is on driving. Any codes has appeared. What might be a problem is it MAF sensor or coli or idle air control. Any suggestions?. Thanks!!!

Sounds like it could be a malfunctioning engine coolant temperature sensor. What year is your QX4?

I would try to clean the MAF sensor. Use MAF cleaner spray only. The MAF is secured by 2 T20 tamper-resistant screws, so you may need to obtain the appropriate bit. Disconnect the negative battery terminal before removing the MAF sensor wiring harness. Clean the throttle body as well, use throttle body cleaner spray only.