Spark Plug Replacement

New Topics Forums General Discussion 2004 – 2009 Nissan Quest Spark Plug Replacement

This topic contains 5 replies, has 5 voices, and was last updated by  prgonzalez 5 months, 1 week ago.

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  • #6705

    Oldman
    Participant

    Finally decided to change the spark plugs after more than 148K miles. The old plugs point were definitely worn out. The new ones had longer tips. If you’re brave enough to try it on your own, here’s the breakdown of what I had to do:

    1. Remove engine cover
    2. Remove air box all the way to throttle body
    3. Remove throttle body for room to reach the blasted bolt on the back of the plenum that hangs a coolant hose. Plus it’s good to clean the throttle body. I could hardly see space between the butterfly valve and the body b/c of oil build up
    4. Remove coolant lines from the throttle body and plug the water coming out with a rubber plug (from any auto parts store). If it’s too hard to reach the clamps, just unclamp the other end of the hose.
    5. Unhook the vacuum lines as in the following 3 pics:
    solenoid

    vacuum tank

    plenum lines

    6. Remove the EGR solenoid and temperature sensor connector and bracket:

    EGR

    7. Remove EGR tube from both ends (sorry, only have a pic of the upper connection to the intake manifold)

    EGR Tube

    8. At this point I ended up unbolting the two halves of the manifold. Remove the bottom two bolts before removing the top two. Everyone on youtube says the bottom two bolts (specifically the passenger side one) was impossible to remove. It turned out it wasn’t too bad for me. I have skinny hands and was able to reach down with a straight box wrench and turned it loose with two fingers. The four bolts are 12 mm. The bottom bolt on the driver’s side is tricky to remove. I had to use an S-shaped box wrench from harbor freight (12mm) in order not to hit the top of the coil and damage it. There is very little wiggle room there.

    9. Remove the two bolts that anchor the plenum below the throttle body. Theyre 12 mm.

    10. Loosen the manifold bolts (3 bolts and 2 nuts on the side). Theyre all 12 mm. You can make room between the two halves now by pushing the back half in a bit and lifting the front half toward the front of the car. Set the big half aside out of the way.

    11. Now you need to unhook the wire harnesses (the green connectors in the pic below). Squeeze the plugs and pull straight up. Then pull the harness side up from the bracket using a big pick (I use the harbor freight pick set abt 6 inches long). Amazingly they pulled out with no major issue.

    wire harnesses

    12. You can see two hoses on the back of the plenum. Unclamp and pull them out. There is one bolt (12mm) on the back that hangs a coolant hose. Take that off too. Now you can remove the back plenum completely and have all the space you need to remove the coil packs. I use the PLFR5A11 OEM plugs. Those are not cheap, over 50 bux for six.

    13. After the plugs are replaced you want to plug everything back on the back plenum. I decided to uninstall the bracket for the green wire harness because I don’t think it will cause any issue from vibration. Makes it easy to remove the back plenum next time. See this pic of the back of the plenum:

    plenum back

    14. When the back plenum connections are all back to the way they’re supposed to be you can put the front half back on. Tighten bolts and nuts to 14 lb.

    15. Continue reinstalling the little things: clean throttle body (5mm allen wrench), throttle body coolant lines, EGR tube. EGR temp sensor. Vacumm solenoid, tank, and lines.

    16. Reinstall air filter ducts and box and tighten the connections and you’re done. Takes about 6 hours for the first time. Next time it will probably take about 3 to 4 hours.

    #7111

    jlkwiththree
    Participant

    Did this one myself a few months back. Took weeks for my hands to heal from all the little scrapes and lacerations. I wonder how many Nissan engineers got fired (or should have been) for the idiotic design of this intake set up.

    #12071

    Bookmdano
    Participant

    I need to replace my spark plugs on my 04 Quest and I am not looking forward to this job. Is it also wise to replace the coil packs on the back of the engine while you have the access? Are the after market coil packs a good idea? My vehicle has 135,00 miles on original plugs and coils.

    Thanks in advance for any info.

    Danny

    #12081

    prgonzalez
    Participant

    Spark plugs are recommended to be replaced around 100,000 miles. My experience with after market coils is not good.

    What you can do is to look for the original coil brand and model in the internet. If you can afford replacing the packs hard to reach in the back, then go for it. Keep the originals for emergencies. If the originals last this long, a fresh set should give you another 135,000 easily.

    #12121

    Canada-Q2005
    Participant

    I am at 100K miles and recently pulled the front row plugs to gap them. They were at the specified gap and did not show any signs of decay. So I put them back and decided to give it another 30K and re-test. Those platinum plugs from NGK are amazing.

    #12161

    prgonzalez
    Participant

    The recommendation for replacing the spark plugs is not a gap issue. The platinum material will not wear as the old spark plugs from 30 years ago.

    The replacement is necessary because the porcelain gets contaminated with the combustion residues and this contamination reduces the efficiency and performance of operation of the spark plug. This contamination will affect the combustion quality leading to misfiring. The recommended interval of 105K miles is to keep your NISSAN operating at top condition.

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