Xonatron

You should still change your oil to clean out the dirt.

Derek Dee

iTrader: (19)

Yes you are right. I should.....

redz85

I got my z in the fall last year and had it down for the winter and I found out that its burning anlittle more than 1qt every 3000 miles and the mileage is 67000 on the car and I tried to talk to my nissan dealer and they basically told me that since the car wasn't bought with a extended warranty im on my own

Bigsyke

Ok, this may be a stupid theory for the rest of us stuck with extreme oil burners, but I had an idea..

I've been scouring nearly all OC related threads for a year or so, and It seems that the revup OC is from the rings during deceleration [Not the PCV valve]. A clogged PCV valve worsens the problem because of increased vacuum (or less of a vacuum leak exposed to the combustion chamber). It certainly seems for me (now 1qt every 200-500 miles), that I'm even igniting the oil during deceleration, audible by extremely loud pops/pinging inside the engine. The sound is similar to rocks hitting the firewall. This is more extreme after a hard WOT pull and letting off. Analysis determines it is not an exhaust leak or backfire. Plugs are ashed up relatively quickly.

The theoretical fix would be a valve/regulator that opens at a specific vacuum. Idle, the valve remains closed at -21 inHg, but the valve will open at -22+ inHg, or whatever set on the regulator. Could this technically prevent or lessen the oil being sucked into the combustion chamber. I would be concerned about a massive vac leak on deceleration, but all fuel is cut anyway above 1500 rpms, therefor vacuum would lessen below that. I couldn't see the ECM adjusting for that on deceleration; although I will need to freshen up on the FSM fuel controls.

I have tried just about anything minus a rebuild. I cannot afford to keep buying $60 sets of plugs every couple thousand miles and dumping $8-16 of 0W40 in everyday. Any suggestions are welcomed.

akuma69

I just use a thicker oil. Solves most of the issues.

Xonatron

Bigsyke, I would love to help you out, but this is beyond me. Interested in what you find out. Curious what your engine would look like next to another 2006 without the oil burn.

Wu-Watt

iTrader: (24)

I think it's old news. Try to do as many cooling mods as you can and check the oil often.
My car has been ok, and I track it.

Bigsyke

Almost 1k miles since the last oil change, and no visible loss of oil. I cleaned the tailpipes on my last OCI and they are still relatively clean.

I stopped engine braking, or made sure I didn't engine brake/coast in gear above 2500 rpms. This is less than ideal, and definitely not safe, but at least I'm not going to be pre-igniting, fouling plugs or o2 sensors.

Still doesn't change the fact that burning that much oil will cause damage, and foul plugs and o2 sensors much quicker.

Edit: I started eTuning recently. Consumption has slowed even more. My AFR was running in the high 15's.

Tony1M

My wife and I are looking for a nice 350Z. In case I should run across an '05 or '06 with a rev-up engine, other than monitoring oil consumption over a period of miles (which, let's face it, is a difficult thing for a potential buyer to do), is there any test of the exhaust that can determine if a particular engine is burning an abnormal amount of oil?

Thanks.

Bigsyke

Update: Came to find the VQ's PCV system is faulty. Probably has no effect on revup OC, but I have gone through various setups and testing to come to this conclusion.

It took a great deal of pressure to open the PCV valve while blowing through the intake PCV hose. I then made a custom PCV orifice while retaining some slight restriction, and blew 3 qts of oil out the tailpipe in about two miles. I have a rather large baffled catch can. It drank oil like a straw was in the sump. The ID of the lines are way too small.

The #1 cylinder's plug was always excessively ashy compared to the ashiness of the rest of the plugs. It would make sense the PCV system is draining into cylinder 1, also throwing the AFR's off and indirectly worsening the situation by affecting plugs and O2 sensors on bank 1 (passenger side).

Properly bypassed the PCV system again by venting from all 4 VC ports, but data-logged this time. AFR's were much more consistent between banks on closed loop. Bank 1 was about ~0.5 leaner vs 1.0-1.5 leaner than bank 2.

I don't really burn after a fresh oil change, but as the OCI goes on, I start burning more and more and notice a large blast of smoke when hitting the gas. Running Mobil1 0w40, and added about 6 qt's my last OCI. So far no consumption yet while driving hard with bypassed PCV valves, although I'm sure it will start once VI wear out and the flash point reduces from fuel contaminates.

I would suggest bypassing the PCV regardless. It's pure garbage.

FYI, I'm a huge TBN/TAN nut, so I advocate a proper PCV system. This specific engines PCV is a joke. The only good thing about it is evening out the AFR between cylinders, but cylinder 1 happens to get nothing but oil so it's counter-productive. Rip it out.

pfregeolle

iTrader: (15)

Wouldn't mind seeing some photos of how you went about your bypass.

Bigsyke

I'll possibly snap some later today.

- Drilled out PCV valve, reinstalled and ran hose down away from exhaust. (capped plenum port).
- Cut middle PCV bypass in half, rotated each hose to point down.
- Intake PCV hose has a ghetto breather on it for now. Capped intake tube with a 5/8th cap IIRC.

pfregeolle

iTrader: (15)

Cool, thanks man!

Armitage

iTrader: (15)

I'm at 141k and my OC is getting bad, gotta be burning a qt every 750 miles. I've done things like an oil catch can, oil cooler, etc. but it seems to continue to get worse. Reading back only a little bit, it seems like a fix was never really found, I see talk of the PCV, rings, engine braking, etc.

Honestly I'm thinking what I might do is buy a spare motor over the winter, have it built, and swap it in. After 10 years and 141k miles, this is the ONLY thing about this car I've had an issue with.

BakaN20

iTrader: (26)

So would this work for changing out the pcv valve:
http://projectimport.com/store/350z-...-breather-kit/

As for venting to atmosphere the pcv and the driver side, will there be any issues? I read somewhere about vacuum being needed somewhere, but too many threads.

Bigsyke

That won't work.

You do need the 3/8'ths vacuum cap, but this is still leaving the drivers inlet side connected. Also, even with both the PCV valve drilled and vented, and the drivers inlet hose vented (intake tube capped), the orifice sizes are too small to properly vent.

You must also either snip the balance hose connecting both valve covers, or install 1/2'in breathers on both.

To vent using breathers, you need;

1x 3/8ths breather
1x 3/8ths vacuum cap
2x 1/2 breathers
1x 5/8th breather
1x 5/8ths vacuum cap.

I just have hoses running downward.

Ricky Calvillo

I own a 04 350z and the gauges of oil and volts needle is not working, nor is the trip computer where it indicates the speed, DTE, MPG, etc. But they light up tho just not reading anything, I checked each and every fuse inside the vehicle, from the two fuse boxes up from by the battery, to the ones down below by the clutch, and I checked it using an electrical tester. I even removed the center console and checked the connection behind the gauges but everything seems to be fine, I unplugged, cleaned and plugged back in, but I have no where else to go, it's just weird how the needles and trip computer don't work but it lights up.

Ricky Calvillo

I own a 04 350z and the gauges of oil and volts needle is not working, nor is the trip computer where it indicates the speed, DTE, MPG, etc. But they light up tho just not reading anything, I checked each and every fuse inside the vehicle, from the two fuse boxes up from by the battery, to the ones down below by the clutch, and I checked it using an electrical tester. I even removed the center console and checked the connection behind the gauges but everything seems to be fine, I unplugged, cleaned and plugged back in, but I have no where else to go, it's just weird how the needles and trip computer don't work but it lights up.

Zed Wyatt

So to my understanding after reading through all this is that 10 years later there is no fix?

e30cabrio

iTrader: (30)

The fix is simple. No 06 6 speed Z.