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Low Oil Pressure at Idle

I have a twin catch can setup with a check valve, as suggested by Sh0velman. Maybe I will tweak my set up and see if that helps. I plan on

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Old 07-17-2015, 11:51 PM   #16 (permalink)
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I have a twin catch can setup with a check valve, as suggested by Sh0velman. Maybe I will tweak my set up and see if that helps.

I plan on doing some maintenance this week when my shipment arrives, oil change / oil pressure sender replace / turbo air filter replacements.
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Old 07-25-2015, 11:58 AM   #17 (permalink)
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Update - Changed out the sending units when I did an oil change yesterday, didn't fix anything.

I have a feeling the cause is the check valve in the OCCs. I thought the heat was just a coincidence, the day after install is when the temperature sky rocketed.

With the check valves removed, wouldn't it pressurize the cans when I am in boost and essentially make them useless?

Ideas?
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Old 07-27-2015, 06:06 PM   #18 (permalink)
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Hey, I replied to your Facebook message too, but I'll post here for posterity's sake.

There's absolutely no way that oil pressure is being affected by anything related to your catch cans. Even if they were plugged closed you'd have the same oil pressure, air is compressible, oil isn't, and a a pump like an oil pump thrives on back pressure.


Does the gauge show pressure at start up that falls off after warm up? Are your "under load" pressures identical to what they were before?


It sounds to me like a conductor has gone high-impedance on the sensor circuit, causing an offset that drops to zero or near zero once you get the normal pressure drop as the oil thins out. Was ANY modification done to ANY wire related to the sensor or to anything else in the same harness?


Is it possible that you jiggled something loose or perhaps inadvertently got a harness somewhere where it got heat damaged? The insulation on the OEM wiring isn't particularly high temperature, exhaust parts or gasses will melt and burn it in short order.


This is on the assumption that you are piggybacking the OEM sender for your external gauge. If you have TWO senders on completely different circuits both agreeing that you have low pressure, it's hard to argue that there isn't a real issue.


If your external sender is on a sandwich plate, it's going to be on the part of the oil circuit that is going into the oil filter, if you have low pressure right there at idle, but normal pressure at speed, I have to think the pressure regulator in the pump is faulty in some way. I believe it's just a spring-type regulator, and if the spring has failed it will be venting most of the flow back into the crankcase, at speed the pump will have the flow to overcome that, at least partially.


My advice in the immediate sense is to not go above 4K RPM unless absolutely necessary, I'm going to check the FSM and find an oil circuit diagram. I'll post what I find.
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Old 07-27-2015, 07:48 PM   #19 (permalink)
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Quote:
Originally Posted by Sh0velMan View Post
Hey, I replied to your Facebook message too, but I'll post here for posterity's sake.

There's absolutely no way that oil pressure is being affected by anything related to your catch cans. Even if they were plugged closed you'd have the same oil pressure, air is compressible, oil isn't, and a a pump like an oil pump thrives on back pressure.


Does the gauge show pressure at start up that falls off after warm up? Are your "under load" pressures identical to what they were before?


It sounds to me like a conductor has gone high-impedance on the sensor circuit, causing an offset that drops to zero or near zero once you get the normal pressure drop as the oil thins out. Was ANY modification done to ANY wire related to the sensor or to anything else in the same harness?


Is it possible that you jiggled something loose or perhaps inadvertently got a harness somewhere where it got heat damaged? The insulation on the OEM wiring isn't particularly high temperature, exhaust parts or gasses will melt and burn it in short order.


This is on the assumption that you are piggybacking the OEM sender for your external gauge. If you have TWO senders on completely different circuits both agreeing that you have low pressure, it's hard to argue that there isn't a real issue.


If your external sender is on a sandwich plate, it's going to be on the part of the oil circuit that is going into the oil filter, if you have low pressure right there at idle, but normal pressure at speed, I have to think the pressure regulator in the pump is faulty in some way. I believe it's just a spring-type regulator, and if the spring has failed it will be venting most of the flow back into the crankcase, at speed the pump will have the flow to overcome that, at least partially.


My advice in the immediate sense is to not go above 4K RPM unless absolutely necessary, I'm going to check the FSM and find an oil circuit diagram. I'll post what I find.

The pressure at start up seems normal and then it tapers off after a few minutes of running, under load pressure seems very similar if not the same as before.

The aftermarket sensor is located off the GTM adapter when I have my oil temp sensor, the OEM wires and the aftermarket ones are in the same heat proof shield that GTM used when they did my initial install last year. So I believe they piggy pack off each other, but I did not remove the heat shield to double check.

I thought I was careful in the catch can install, none of the wires should of been knicked or knocked loose, when I had it on the lift Friday everything seemed ordinary.

I'm thinking what you said in the FB messages could be correct, maybe the oil pump is gummed up. I'm going to drop it off at the local dealership tomorrow and get the head techs opinion. He has worked on my car before the catch cans and knows the ins and outs of my set up.

Thanks again everybody, I can't say how thankful I am for the help and knowledge.

I just want my Z normal again, I hate not driving her!

Ill
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Old 08-14-2015, 01:52 AM   #20 (permalink)
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Quote:
Originally Posted by Ill View Post
The aftermarket sensor is located off the GTM adapter when I have my oil temp sensor, the OEM wires and the aftermarket ones are in the same heat proof shield that GTM used when they did my initial install last year. So I believe they piggy pack off each other, but I did not remove the heat shield to double check

Ill
Your prosport oil pressure gauge has its own sensor. The GTM oil block has both turbo feed lines,the factory sensor and I believe the sensor for your prosport gauge. The heat proof shield around the wires might just be some split loom.

I don't think anyone has asked you yet but what viscosity oil are you using during the summer?
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Old 08-21-2015, 10:53 AM   #21 (permalink)
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Update

Received a call from the tech yesterday when I was at work. I don't remember the specifics but one of the gaskets blew out in my upper oil pan and there was a crack in the bolt for the oil pump. Waiting for parts to come in and then they will reassemble everything and it should be good to go, no major damage was seen anywhere else.

I'm going to go after work to chat with the tech and get more information and the diagrams showing the damaged parts.

It's going to be pricey to fix, but it could've been worse.
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Old 08-25-2015, 12:59 AM   #22 (permalink)
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Fyi VHR engines don't have oil pan gaskets. Its all "Nissan bond" and I would highly recommend reusing the same stuff to re seal it. The oil pump bolts to the engine block hopefully that's not what's cracked.
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Old 05-21-2016, 04:31 PM   #23 (permalink)
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Did you figure out what the culprit was. Was it the gasket and oil pump bolt after all?
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