Rufus007

No probs all good. I've seen several threads talking about the VTC covers, but I haven't seen any where they said "i've gone ahead and replaced them, and it worked". The only thing I've seen definitively fixing the problem was the elusive software update. Just for curiosity I dropped into Nissan today, about $900 each for the covers, or about $650 each delivered from the US. Faaark either way. I've got three different recordings on the oil & water temps when I first noticed the stutter after cold start: Water 82, Oil 49 Water 83, Oil 53 Water 81, Oil 47 So it appears the the VTC is probably kicking in at around the 80 degrees coolant temp. Ideally it would be dependent on the oil temp, at a guess over about 55-60 degrees to be safe. So this is maybe what the software update changes, but only a guess by me - no sure answer on this one. I'm still thinking about this 3mm to 4mm thermostat hole drilling business to slow down the coolant warm up rate, and give the oil a chance to warm up a bit more before the coolant hits 80 degrees when the VTC kicks in. Just delaying by a couple of minutes would work I think (I don't want excessively long warm up times). Bought a thermostat gasket while I was there for $6.60 so I can think it over during the week, maybe do it on the weekend. PS, second day on the 5w30 and the stutter happened. Felt no difference with engine characteristics etc.

@colin.ssc - before I go ahead messing around with the thermostat, I've tried one last thing on this otherwise lazy Sunday. Today I filled her up with some castrol edge 5w30 (the viscosity as per service manual, so far I have only used 40 weight oils). Will report back in a few weeks on this

Bluetooth ObdII from jaycar for $70 works well. I use that and ndsIII on my 07 v36. I have tried eBay adapters that don't work.

Ok I've just logged and graphed coolant vs oil warm up times at idle only. The graph does show how fast the coolant really does warm up in this car. My next step is to figure out at what coolant temp the VCT stutter starts and stops happening - this might take me a little while, obviously I need to drive around for a bit until I get some data. X axis is time in seconds, Y axis red = coolant temp, blue = oil temp After 2 mins of idle, coolant is about 53 celcius, after 3 mins about 60 celcius. Oil temp lags way behind...

Good info thanks, that's why I'm asking for thoughts like this before I do anything. I'll monitor coolant temp with my obdII and see if mine has a similar warmup pattern to yours

Okay I've got another little experiment to try first before I get out the drill. Can anyone else try this - turn the heater up to full blast as soon as engine is started even if this causes undesired side effects, eg sweating. This might help slow coolant warm up times. I'll report back but have been riding to work lately as weather is good

Lol, so your opinion is 'just do it'

Not sure if its the colder weather lately, or what, but mine has started to do this stutter occasionally again lately - maybe 1 in 4 cold starts. So I started thinking of some solutions for this. I rang a tuning shop in Brisbane who said they don't have any software with the ability to delay the VCT operation. I came up with another idea and want peoples thoughts about this as a possible solution: Drill a small hole in the thermostat to slow down the coolant warmup speed. These cars really do heat up quickly in only a couple of minutes eg I'll leave home, make two turns and the coolant gauge will be at normal operating temp. As the VCT operation is based on coolant temp, this might delay the VCT operation long enough to heat the oil up a bit more. At most I'll be out of pocket one new thermostat and whatever time it takes if this doesn't work. Opinions on this?

Get yourself a copy of the 2007 g35 service manual - its listed in there. The plugs you listed are 2 full steps hotter then OEM - Be careful. I buy lots of things online, one I don't recommend is spark plugs. Received some once knocked up and in bad shape - had to send back.

Factory OEM for vq35hr are Iridium - Denso FXE22HR11. Got mine from Nissan, they were $34 each though. Maintenance schedule on these is 170,000km but I recommend replacing earlier.

Not sure whats updated software wise, but will be pretty hard to get the update in Oz. Still think a good way would be to get your tuner to delay the VCT operations for a few more minutes when engine is cold.

Found an Infinity technical bulletin on this one: http://workshop-manuals.com/infiniti/g35x_sedan_awd/v6-3.5l_(vq35hr)/powertrain_management/prom_programmable_read_only_memory/component_information/technical_service_bulletins/customer_interest/07-045a/apr/09/engine_controls_cold_start_rough_idle/idle_fluctuates/

How old is your car battery (not remotes batteries)? I've had cars do strange shit from an failing battery before. Plus you said it works better when interior lights are off (so less drain).

Seems to be a problem from several manufacturers around 2007 to 2009. I left mine out in the sun for a bit and then 'polished' the sticky off with some bug and tar remover. That does work. Apparently acetone might help also, but be careful. Edit: I should mention to wipe clean with water when finished

I think there was some early vq37vhr affected also

So if the VCT angle sensor is accurate, do you then think the wrong VCT timing is being caused by the VCT actuators? If so maybe that's what the revised VCT actuator covers might address? Judging by the lack of response so far this doesn't seem to be a large issue, and as I mentioned mine was sorted just by changing the engine oil to castrol edge.

I always thought this issue was quite obviously VCT related though, like I initially posted. I also agree about the water temp vs oil temp disparity. I have previously bookmarked something along these lines also: (look at 13th post) http://www.350z-uk.com/topic/64601-my-350z-hates-being-serviced-help/ If not inaccurate VCT control and setting, what do you think is causing the stutter then?

I would think so, have seen several people using NDSIII to monitor the widebands...

I can only recite what I've read elsewhere regarding what people think is this issue. But the community agreed cause is that the VCT sensor isn't overly accurate. At low temperatures especially, the sensor is then setting the cams in the wrong place causing to much overlap at low rpm where overlap is not wanted/needed. And that is where the stutter comes from - low compression due to overlap, not fuel or spark issues. So the overall solution here *might* be to delay the time the VCT's kick in at (giving the engine a chance to warm up a bit more first) - and I think this is what the oem software update does also.

In a forum I read somewhere, there is an oem ECU update that fixes the problem... So it's possible software wise...

Is the stuttering still reduced running edge 0w40? Also does it still only happen in the first couple minutes of warm up? If so just keep using the castrol oil I guess. It used to happen to mine only below 2k rpm, so maybe try to drive just a little over 2k until the engine warms up? You can force the exhaust valve timing to relearn with Nissan consult III software apparently, and there is also an android app called NDSIII that can do this: https://play.google.com/store/apps/details?id=com.nissandatascan.ndatascaniii&hl=en I found the ebay bluetooth OBDII adapters do not work with NDSIII, but I found one OBDII adapter from jaycar works well with NDSIII: http://www.jaycar.com.au/Automotive-%26-Mobile-Security/Car-Alarms,-Protection-%26-Accessories/Tracking-Fleet-Monitoring/READER-OBD2-BLUETOOTH-4-0-ENGINE-CODE/p/PP2145 Final option before replacing VCT covers could be to get a tune to delay the time/temp until the VCT starts operating hope that helps

Just checking in for an update on how she's running now? Ie with new fuel pump etc if you have that installed now.

That must be the German castrol 0w30 is it? Think you can only get 0w40 retail in oz.

Awesome. Just for forum records, what oil did they use?

Glad to hear the oil helped somewhat. In the 350z forum I linked, there is some mention that fitting revised CVT covers worked. Depends how much it bothers you I guess.