Tricky-Ricky

Is that not the link you first posted? and like I sad after looking at the manual the pressurised oil feed for the VVTI is sealed via rubber "O" rings, and although they are referring to the HR version, I really cant see them reverting to a gasket.

Wheel bearing then.

I ran these on my 350GT

Most engines including turbocharged respond positively to gas conversions, if done properly, just like anything else the bad ones get the bad publicity.

The trouble is average fuel computers lie, the only real way to know for sure is to brim the tank and see how much you have to add next time.

Just out of interest, for those getting 35mpg on a run, do you by any chance own UK spec Zs?

Im trying the reasonable approach with him first see what he says lol Heres another video of the noise, this isnt my car its off youtube but its exactly the same noise Ahh yes! that's conclusive, sounds like the oil was already dangerously low when you first drove it, and the pump started to pick up air as it was being driven and loose oil pressure...so by by bearings,the owner must have know that the oil was low, or it already had problems, check the viscosity of the oil that's in there, I am wondering if its had thicker oil in the mask the problem, bad luck fella, hope you get your money back.

Although to me the video noise is not conclusive, it doesn't sound like a rhythmic knock, but by your description I would say you have problems, as said take it back.

Too high and too low could indicate a problem with the oil pressure relief valve, but low pressure is more of a cause for concern, as it could also indicate worn bearings or pump (unlikely).

Changing oil grades wont make that big a difference, unless you test the true oil pressure with a mechanical Gauge you wont know for sure, you could have a problem with the pressure relief valve.

One thing you will notice is the Z is a torque monster in comparison with the type R.

One thing worth noting Jay is that with the EML already on if another problem occurs you're not going to realize unless you read the code & spot a new error code. You can buy code readers cheap enough from eBay and I believe some of them allow you to also clear the codes. That way you can check it regularly just to make sure it is on just because of the known O2 sensor error or whether something else has occurred. Link: http://www.ebay.co.u...=item2344098d4d I don't have one of these myself but always planned on getting one, it's just other things popped up like supercharging. Take a look on eBay and you might find one even cheaper than the one I linked. Good point! which I forgot, as I used to run ECU data-scan on mine so I was always aware of any new faults.

Only if you keep getting a CEL for the cat O2 monitors, and if your going up rev you can have them turned off. It wont hurt the engine anyway.

The capacitors in the ECU are so small a value they will discharge themselves in less than a minute, as the ECU has its own earth, also the if you disconnect the battery negative, pressing the brake will not earth the system, CELs are stored on a separate flash memory and will be retained until they are erased by diagnostic software or pedal dance.

Extra guages mean extra things to worry about. Very true..... but for me gauges have saved me more than one engine in the past.

Doesn't it at least have a low oil pressure light like most cars?

Just had a quick squint at the DE manual, and it appears that the VVTI oil feed comes through the rear to the front of the timing chain case from the head using spigots and "O" rings and not gaskets, so unless one of these has failed and is venting oil internally to the chain case, or externally from the case to head interface, there is no other place to loose a lot of oil pressure apart from thought the head gasket itself, unless of course there is a serious bearing problem somewhere.

Couldn't be bothered to read the whole thing, but from what I can gather, are they saying a gasket failure is the cause? and if so the only oil feed I can think of that would loose enough pressure to cause a drop like that would be the VVTI oil feed, but will have to have a look at a HR manual to tell for sure, I only have the DE, has anyone got a link to an HR manual download?

The whole leaving the battery disconnected for minutes/hours thing is a myth, simply disconnecting the power is enough.

If you disconnect the battery for a few seconds and reconnect, it will reset short term fuel and knock tables, but AFAIK it will not clear stored error codes, these are retained until cleared with suitable interface/software.

Stock seems to go rather lean in the peak torque areas?

If you mean post mapping AFRs? then no. I would be very interested to see a post up-rev Innovate AFR with the same scale, but I don't think many people use Innovate wide-bands.

As I said on your last two posts on the same problem... where you where also given plenty of things to check, you really could do with taking this to an audio installer to get it sorted as you clearly have no idea.

Did you remove the whole lot or just the spring?

I actually found that fitting BC coil-overs to my Skyline 350GT made quite a big difference, in that they did not over damped like most, but the 350GT is about 100kg more than the Z so I think that's where it came from, Having fitted both coil-overs and ARBs to other cars, and mostly found it too stiff without the benefits it should have, I am now very reluctant to fit both to a road car.