RobPhoboS

I've spent days looking at threads on this forum, as well as others with similar misfire problems, youtube vids etc but now I thought it's time to ask !!!

So my car has been idling like this for some years now (2004 DE 6MT 115k), I had it remapped the same time when I put on the plenum spacer, test pipes and exhaust.
This was done by a very highly reputable 350z garage here in the UK, there are only a handful.
They did warm me that occasionally the o2 codes would come up, even though the test pipes have the spacer built into them.
No problem, when they do come up I just quickly clear them with Torque Pro. This tends to only happen during colder days when it's idled for a few mins before setting off, very random when it happens but that seems to be the catalyst for it.

There isn't any hesitation when accelerating, feels pretty good and is at 300bhp on a couple of dynos.

Anyway, I didn't really think about the idle sound until recently at my first track day and I got a P0300 error code appear.
It happened on my sighting laps, going very slow.

Now what I'd like to point out is that this p0300 has never occurred before, part of me wonders if I needed oil topping up a touch more (as the week before I changed all fluids and probably should have added a bit more oil to the engine).

I was at a loss but as the car was idling my friend said it did sound a bit like a coil pack not giving enough for the spark perhaps.

This is how it sounds:

Which sounds very similar to this guy:
https://my350z.com/forum/maintenance...on-inside.html


I'll get another clip with the occasional pop it does.

This is the list of things I've done so far.

New spark plugs (images posted here )
Cleaned injectors + new lower o-rings
New cam sensors - although going to test them as getting hard warm start now.
Checked for air leaks.
Contact cleaner on all of the harnesses that I could see as well as the maf and throttle body (didn't touch flappy).
Accelerator pedal release position, throttle valve closed position, idle air volume learning.

Tested coil pack resistnace
These are the Ohm readings I got set to 2k (not sure if that setting is ok):
New coil = 158

Cylinder 1: 164
Cylinder 2: 152
Cylinder 3: 153
Cylinder 4: 153
Cylinder 5: 147
Cylinder 6: 164

I'm thinking of buying a tool like this to check the spark from the coil pack:
I have 2 new coil packs, so I will go through changing one at a time to see if that cleans up the idle too.

This is what came out of the injectors:


The other things I can think of, crank sensor, knock sensor (+harness).
Or maybe the MAF sensor isn't doing it's job properly.
Any help would be much, much appreciated.

RobPhoboS

Here is the coil pack spark test:

http://www.youtube.com/watch?v=7fZhWTCUsS4

Note - on Cylinder 2, it looks like there isn't a spark for a while but I'm sure I saw it with my eyes, just not on camera. Easy enough to try again though.

i8acobra

iTrader: (6)

When you pulled the plugs out, did any of them have oil on the insulator (the white ceramic part above the threads)? Spark plug hole seals in the valve cover going bad and filling the plug tube with oil is a common problem. The fix is to replace the valve cover (seals are built in).

RobPhoboS

No oil that far down, just about half way on the threads.
I already used the R&D kit a couple of years ago and drilled out the old seals/grommets, replaced them etc.
It's just the top of the tube that needs sealing now, which I'll do soon.

These are the old plugs:
They all roughly look the same except for cylinder 1:

RobPhoboS

Actually one thing I'm going to do as a just-in-case, is to put the spare new one and good older working one onto 2 and 4.

RobPhoboS

I swapped Cylinder 2 for a new one, and Cylinder 4 for the spare old one...no change hah.

So I managed to get onto a 'track day' at an airfield on Saturday, it was sleet and snow for my first time on track - take 2 -
But it was really good, and most importantly no issues !

So now I'm wondering if the fuel I used just before the previous track day was a bit dodgy. I always use the same stuff for the last 4 years (98 Shell V-power) but sometimes if their fuel tank is low or just been replenished it could stir up some crap perhaps ?

I'll still run it up to the original garage that tuned it to see what they think regarding the mapping.