Hey guys, i own a 2007 G35x & i started up the car today getting ready to head to work, i let the car warm up then all of a sudden boom vibrations began & rpm was up & down all around, i go to the exhaust and it clearly sounds like a misfire i also took it on a drive around the block & it clearly sounds like a misfire, okay cool. The thing that's puzzling me is there is no codes no check engine light so i'm as a loss of what's causing the misfire. Has anyone experienced anything like this before? Appreciate everyone & their time.

 

Start the engine and check the coils by disconnecting #1 and see if the engine RPMs change, if not, then reconnect it and go to the next one until you find the bad one. ECM tries to compensate until it can't and then throws a CEL..

 

So i'm getting a strong fuel smell inside the cabin, still no codes or CEL being thrown, haven't been able to get to cylinder 3 or 4 because they're tucked behind the throttle body's, but when i disconnected 1, 2, 5, 6 the car started shaking even more. i put fuel cleaner in the tank and the car started smoothing out for a few seconds but then went back to sputtering leading me to think it's either my injectors or fuel pump. i managed to pop in a spare OEM fuel pump i had lying around & started the car and it stabled out but began sputtering again. i now have all coils and plugs removed and i noticed cylinder 4 plug is darker then the rest and there was some oil in cylinder 3 & 1 not a lot but some. at a lost of what's going on because when i rev the car slowly it smoothens out, im starting to think i have clogged injectors or some fuel issue

 

Fuel smell is unburned fuel most likely due to no spark in one or two cylinders. When you disconnect the coil pack plug, the engine should shake, if it doesn't then that coil pack is bad. I can get to all coil packs with a flat blade screwdriver. Don't start swapping out fuel pumps or fuel injectors like i did, big mistake! No spark, no fuel burn. If you have access to a decent scan tool like xToolD7, Thinkscan, Autel then you can probably see a pending code in the ECM. I had that when one of my coils packs went bad half way and made spark but not enough spark under load.
Here, this is what i use in my VQ35HR without any issues: You can also see my thread about my 07 Long cranking times and hot restart issues.

 

Copy that i'll try again tomorrow, gonna get 6 fresh new plugs and 3
coils since plug 5 broke coming out and see if it fixes the issue. If not i'll just have to do the dreaded compression test and see if my engine is toast lol

 

I'm using DENSO 3442 Iridium Long Life plugs and i don't drive slow. I don't have any issues since i've fixed it and i hit triple digits daily. MPGs suck on these cars, thanks to the 5 spd trans with crap gear ratios. I have VLSD 3.55 and i'm still at 3200 rpms at 80 on 27" tires. Get new coils and plugs, just make sure the coils packs have transistors between the coil spring and the boot. Pull the boot off to check. Many Nissan engines use the same coils BUT without the transistors since they don't rev to 7800 RPMs..

 

RESOLVED!!!!: Me being me i'm boosting this car eventually so i replaced all 6 spark plugs with NGK Laser iridium's 1406 DILKAR7B11 & got 6 brand new Hitachi IGC0003's like you had suggested and the car is functioning better than before it started misfiring, i'm assuming either cylinder 4 or 3 coil took a **** & that's what was causing the misfiring, weird how it didn't throw a light tho. But yeah the car is actually getting almost 18mpg now instead of the 13.8-14.5 i was getting before. Thanks for the help!!!!

 

I'm glad you're getting 18 mpg! I'm only getting 12-13 on 93 octane but that's how I drive around town I guess..
The VQ35HR engine is very picky about plugs, coils and sensors. If your cam/crank sensor(s) start to fail, ONLY use Denso or you'll be very, very sorry.