help :-(

Hey guys. My cars never missed a beat till now. Started it up this morning and oil pressure was off the scale. It's got no power wat so ever and struggles to get to 100 kmh. ??

It's only done 140,000k and I always service it on time.

I'm lost lol

 

checked all the coilpacks to make sure all cylinders are firing?

 

It would be extremely unlikely the oil pressure would increase dramatically unless you have filled the engine with gear oil.
Time to get out the electrical schematic diagram & the multimeter.
The oil pressure gauge indicating very high oil pressure may relate to an electrical fault.
Whatever is causing the gauge to malfunction could also be causing your driveability issues.

 

Sorry Rob whats your reasoning behind the indicated high oil pressure and doing a leakdown test? not being funny just dont understand. IMHO Ian you have two problems!.
Do you have any top end rattling, ie, hydraulic lifters will rattle if they get no oil
Are you running on all cylinders?
Any smoke from exhaust?

 

Possibly just the earth straps not being attached properly, would mess with the gauge reading (it earths through the block) and cause funny voltage to the ignition system. It's always nice when it's actually one of the simple things so worth checking.

 

I let it warm up again and is running around 5 on the gauge. I'm not sure. Initially was running at 8. It fluctuates with throttle. Not sure....

 

Oil Presure Basics.....

An oil pressure gauge will read higher pressure when the engine is cold & first started, than what it will when the engine reaches operating temperature.
Why? Because the oil becomes thinner as it gets hotter & the pressure will drop.
It is not unusual to see fluctuations in oil pressure as the throttle is increased or decreased.
Why? Because the oil pump speed varies with engine RPM as it is gear driven.
As an example, with the engine at operating temperature, at idle the oil pressure should be around 11 psi & at 3000 RPM, it should be between 51 & 65 psi.

The thing to be concerned about with oil pressure is if it is LOW!
If oil pressure is suspect, a quality gauge should be connected to the engine via a capillary line.

 

is that what oil pressure is supposed to be

I have cold start up oil pressure at 110psi

warm at idle 35-40psi

it revs like a tacho from 35 -100psi psi with the accelerator .


.

 

The quoted figures.......

.....were obtained from the 1994 Nissan Factory Service Manual - Lubrication & Cooling System Section.
It does state the figures are approximate.
There is no mention of cold start pressure.

The '91, '92, '93, '95 & '96 FSM's also state the same pressures.
The additional pressure you are seeing could be related to the pressure relief valve.

 

Are you able to get some video Ian, post to YouTube or something?

Obviously if its making horrendous noises it would be a serious oiling issue. But what you are explaining seems to be a 'point in time' failure rather than a gradually progressing fault.

Are you using a stock oil pressure gauge, or aftermarket? When was your last oil change, what grade oil?
When was your past upgrade / inspection of coil packs, PTU, TPS?

I've had an issue where the coil pack failed, and overfuelled a cylinder. You don't really notice this at high speed. This overheats the cat convertor, chokes it up and you physically cannot gain/maintain speed. Possible scenario?

 

I would tend to believe that the two are not related.

I have replaced the oil pressure sending unit on my TT almost yearly since I have had it. They are incredibly unreliable, pretty much junk.

Oil pressure won't affect anything unless it is non existent and the lifters wont pump up enough to open the valves.

Have you run codes? It is probably something simple like a clogged fuel filter or a failing PTU, but running codes is where to start.

 

Have exactly the same oil pressure figures as you on the engine that I have just rebuilt and installed on my track car. Best oil pressure numbers I have seen on any of my VGs. When I had knocked out all the conrod and main bearings I still had 16/17psi at idle after a 10 lap race, I know what it says is minimum in manual but I would be very worried at 11psi.

 

PM me with your phone number and I will drop over and see if I can help work it out - there's too many variables here to comment with not enough information (a video is always best in these circumstances) however I have a diagnostic computer and would check the obvious as well as the codes to start with.

Too much pressure is not a problem generally but lack of power is a sign of something is not right

JC

 

Iv noticed my thermofans are running excessively. The control circuit is fed from the CTS. It's also running abit rich. Perhaps the CTS is on its way out. Not sure how to pull up error codes with the 300zx. Ill read the tech section. Cheers

 

ummm......getting confusing now as it sounds like a faulty thermostat (but that doesn't explain the oil pressure) or an electrical problem (seems most likely-given all the various issues) - possibly a ground/ earth issue?

The oil pressure and problems might be due to mechanical issues in the block as rob260 suggested based on the evolving problems - it might be time to get to the basics by turning the motor over by hand and feeling for pressure on the crank/ valves/ oil pump / water pump etc (sparkies out) but hard to say for sure (its just that you appear to have numerous problems going on) as it still may be electrical given oil pressure works on electrical signal

Error codes are bought up on the ECU via flashes or via ECU talk usb cable / Bluetooth adapter and a laptop computer with diagnostic software