Been getting engine misfires here and there off of Cylinder 02 in the last 6 months. So 3 weeks ago I had an oil leak and was instructed to order a new valve cover, valve cover gasket, and spark plug seals. I went and purchased the aluminum valve cover that everyone here suggests, ditched the gaskets and got the OEM Nissan gasket and spark plug seals instead. Asked 2 different mechanics if I needed to order anything else and they said no.... spark plugs are 20km old and ignition coils are 30km old and I did replace those for preventative reasons at 170K - 185K km range. Now the mechanics are saying I should replace the plugs and coils again because "even when they clean the coils on the outside, there could still be oil" inside them. I asked weeks ago if I needed anything else (nothing has changed since then) so Im surprised they are just asking me to replace everything again. After doing more research, I found out I have never replaced the Direct Ignition Coil Boot Kit (6 of them) and that this could also be causing engine misfires. Should I go ahead and order the new Direct Ignition Coil Boot Kit? Or should I also order the plugs and coils as well........

 

You are around 120K miles correct? Is there a code thrown as normally a misfire will trigger one of the P30x codes. Many here have reported upside from just replacing the coil packs they thought were working fine.

 

Yes P0302 has been going on a while now, which is why I changed all 6 plugs 30k ago and all 6 coils 15k ago.... but the code still comes back. Now i've changed all gaskets in March 2025 but recently oil leaked again which is why I am replacing valve cover + valve cover gaskets and spark plug seals again. I am just wondering if I need to replace the "Direct Ignition Coil Boot Kits" or if it's the same thing as an ignition coil / already replaced???

Here's the post from my original issue https://www.myg37.com/forums/engine-...verywhere.html

 

When you bought the new col packs 15K miles ago
ex: https://www.z1motorsports.com/z1-pro...e-p-21716.html

They should have come with the coil boot kits
ex: https://www.sixityauto.com/6-pcs-ngk...052000620.html

New gaskets, new spark plug tube seals, new coil packs with boot kits, newer plugs.

Not sure why there is still a misfire on cylinder 2 unless the oil leak through the plug seal fouled the #2 spark plug. Have you taken it out to check the condition?

 

Yup that is what I thought, new coils should automatically mean new coil boot kits.... boot kits should not be worn out, but if they touched oil can they be cleaned or do they need to be replaced??
They just replaced my valve cover, valve cover gasket, and spark plug seals and told me P0302 is misfiring again. Well, the oil must be coming from somewhere. Or the plug / coil is defective. They should be able to swap the plug / coil with a different cylinder and see if it "misfires" on another cylinder right??
If all fails, could it be bad fuel injectors????
All mileage is posted in KMs, not miles..

 

Moving the coilpack would help you eliminate it as a the culprit. Could try the same with the plug as well.

I have not seen injectors fail, but anything is possible.

 

Personally, I would change all 6 ignition coils. Hitachi builds the Coil Packs for Nissan, so I would see if your mechanic can source Hitachi (Rock Auto carries under "Premium") or just bite the bullet and go OEM (2.5x the cost).

I've seen alot of folks on here and Reddit complain about the low cost coil packs you see online for TGTBT prices, so I'd avoid.

Didn't recommend Z1 CPs because your mechanic will not warranty. I was thinking about upgraded to those when mine start to go out (will DIY).

 

Hello,

2010 G37 Sedan - 194921 miles

I have recently changed my spark plugs - Denso FXE24HR11 - all six @ 194698 miles. Driver side cylinder 4 had oil in the well so I had to replaced the valve cover gasket. Have not change the passenger side valve gasket yet but am looking to. There was no oil in the oil well on cylinder 1,3,5 but the valve cover does have some oil.

So today I was on my way to replacing my wheel bearing & the car had start to vibrate at idle when nearby the shop.. thank goodness. While at the shop in replacing the wheel bearing, the code was misfire on cylinder 5. Told the shop of my recent repair, so they did a ignition coil replacement. I was able to drive home fine & the wheel bearing issue is fixed

I am a little skeptical on the part that the shop uses.. I prefer Infiniti parts but I see a lot of Autozone parts that would get delivered to the shop. I am looking to order an ignition coil (from Z1 or dealership) in the event there is an issue w/ the replacement from the shop. The shop does warrant it for 1 year but..

My question is how far can I drive with the vibration at idle that I had experienced. The Service Engine Soon light came on 1 time but did not stay.. maybe since I was near the shop so did not drive very far.. Also, is it recommended to change all 6 ignition coil as a maintenance or it should be replaced on as a needed basis. I am asking to prepare myself if the vibration happens again. Thanks

 

Cool. Thanks for the input.

Z1 Motorsports has the 6 for $400 (shipping, tax, etc) . RockAuto has the HITACHI IGC0078 - 6 for $380 (shipping, tax, etc)
- 18 months warranty for Z1 - 12 months/12,000 miles for Rockauto

hmmm... which to get..which to get...

 

I plan on using the Z1 units when I finally change mine out.