Guys,
I'm really desperate here. I changed the spark plugs on my 2003 G35 and now I hear a knocking noise from the engine. I'm not 100% sure if it is actually engine "knock" but it sounds like it.

The plugs the car has had are:
NGK PLFR5A

The plugs I was replacing them with are:
NGK LFR54GP

These plugs should work fine from what I read on google. I purchased them from Sparkplugs.com

I'm scared to drive the car with this problem to see if it goes away. There is a bit of a vibration when the car idles or when i let off the throttle from lightly revving it. No vibration while revving.

I was worried that my coil packs were hooked up wrong, but I can't find a diagram to ensure this. I'm pretty confident the coil packs were reinstalled correctly.

Any help. please!~

 

Does no one know?

 

"NGK LFR54GP" If you google that nothing comes up, So I dont think anyone can help you.

 

If you hooked up the coil pack incorrectly, you would be scared to lightly rev it. Still check. If I remember correctly, the drivers side bank is easy to make that kind of mistake on. If the plugs are correct for the application (which I didnt verify), I would start by verifying plug gap even though they come pre-gapped.

 

make sure the coil connectors are going to the correct coils for starters. and why didnt you just go with the oem plugs? if you buy anything other than oem, check and set the gaps.

 

I verified the plugs you have are the correct app, others are having trouble finding it in google because you supplied the wrong p/n "NGK LFR54GP"--- replace the 4 with an A------ngk lfr5agp

 

gentlemen,
I just watched this video:
which clearly shows the coil pack plugs and where they go. So now i know that everything is connected correctly. There is still a vibration but I am going to drive the car and see what happens. Maybe something else has gone wrong...

 

Problem solved.
I don't know what we did exactly to fix this but as a last attempt here is what he tried.

We torqued the spark plugs to 18ft.lbs - they were all pretty much there except the number 6 cylinder was a little loose. Not sure if this was the problem or not.

Then, myself and two other guys watch the video I posted to try and confirm the wiring connections for the coil packs.

The long wiring that is kind of in the middle of the looms goes to the Middle cylinder on that bank(cylinder 4).

Car fired right up with no vibration. Idle was high, around 1,000 but I think a little bit of driver will solve that

 

a spark plug was a little loose? Yup, think you found the problem.

 

I don't know if I would agree to that compeltely but it's definitely a big possibility.