Low Oil Pressure at Idle

[DSMPT]

I couldn't find any good info on the EVO3 housing.

EVO 3 housing has nothing special, work just the same as others. It's just it's for 7 bolt and has air cooled oil cooler ports.

I wasn't aware this was an issue. It seems to only affect warm idle pressure.

I thought the same way, so I stopped to mention about the pressure relief valve since you mentioned this happens only when the engine is hot. But there is still possibility, so before removing anything I recommend to inspect if the relief valve plunger is sliding smoothly in the OFH.

Does the thermostat have anything to do with this?

Yes and No. It depends on the situation and at where you are seeing the oil pressure.
For instance, if you have the pressure sensor at post oil cooler and if the cooler has a flow issue for some reason, you should see the oil pressure lower after the oil temp gets hot. If you have the pressure sensor at pre cooler, you may see higher pressure at the same moment. This is why sometimes people damage bearings by blocking off the oil cooler ports improperly.

You should check if the pressure relief valve is clean without rust/dirt inside and if the plunger slides smoothly. It's not very common but sometimes the plunger gets rusty and gets stuck. This usually happens when you buy a used OFH and install without cleaning. I assumed this was not the cause because you described that the pressure was good before. Another possibility I was thinking was, I don't know if you ported the OFH by yourself, but maybe it's ported improperly. But this too, if so, you should have the low oil pressure issue always from before.

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[4G63510]

I pulled the pressure relief valve. Nothing seems out of the ordinary. Measurements to a stock 2G unit seem the same.

I did port the EVO3 unit, but I only went wider, not longer. I don't think this would affect idle pressure much, but by going wider it should reduce pressure at all RPMs. I didn't measure it when I ported it (and I don't want to remove it right now), but I doubt I went more than 2mm wide total. More likely it's 1mm or less. You be the judge.

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[We're on Boost]

Well, according to Jafro's measurements it would take about 47 psi of oil pressure to even move the piston at all from where it seats:
13 / 0.272 = 47.8 psi

So the piston isn't going to move off the seat at warm idle.
But what's a little less clear is if you went too far towards the top of the piston with your porting.
It looks to me like the port is closed but just barely, in your last picture. It might depend on how much chamfering you did around the bottom edge of the port, which we can't see.
If it is actually closed in that pic, then it should still be closed at warm idle, so it wouldn't effect warm idle pressure at all.

 

[4G63510]

Well, according to Jafro's measurements it would take about 47 psi of oil pressure to even move the piston at all from where it seats:
13 / 0.272 = 47.8 psi

So the piston isn't going to move off the seat at warm idle.
But what's a little less clear is if you went too far towards the top of the piston with your porting.
It looks to me like the port is closed but just barely, in your last picture. It might depend on how much chamfering you did around the bottom edge of the port, which we can't see.
If it is actually closed in that pic, then it should still be closed at warm idle, so it wouldn't effect warm idle pressure at all.

That was my thinking as well. It would be pretty easy to "shim" the spring and preload it so it takes more pressure to open it. So if the issue is the pressure relief valve, then the preload would increase idle pressure. (low flow pressure) At least that's my understanding. I'll have to look more closely at Jafro's graphs to see how much it might need to be shimmed to make a difference. I don't think access to the spreadsheet is available anymore unless someone has a link.

I just looked at my stock 2G unit, and the plunger is more obscured than this pic of the EVO3 unit. I can't find any pics of it without porting, so I can't confirm how much was taken off. Looking at others' pics, it doesn't seem like I went any further than anyone else.
I'll try a shim to see what happens (because that's an easy mod). If not, I'm thinking I need to pull the pan and check bearing clearances :/

This where I stand now:
I measured both my EVO3 and 2G oil pressure valves and all of the parts. There are small, but measurable differences between them. In some cases almost 1mm. The crush washer itself was .24mm different. I looked back at Jafro's numbers and mine aren't quite the same. This isn't an issue since we are using different measuring devices and under different conditions. I often got a .01mm or more difference on my digital calipers depending on the temperature.

So, I took the longer 2G spring I have (it was nearly .75mm longer) and used its plunger as well. I also added a 1mm shim under the spring to add more initial pressure. A rough measurement said this was ~1.3mm longer than the EVO3 parts.

Cold idle saw about 10-15psi increase. Cruising saw little to no change. I'm still getting readings of zero at warm idle, but they are weird numbers. It seems to jump between 0-12psi. It almost feels like it's electical in nature as I can hear the tone of the idle change. I'm sure idle is moving slightly, but less than 200rpm (likely 50-100rpm).

My next course of action before I pull the pan is to get another pressure sending unit. This has been a suspicion of mine for a while, but a mechanical gauge showed nearly the same numbers at the same RPM so I ignored it. If that doesn't work out, I will swap the OFH to the stock 2G unit just to check things before taking the big leap.

I'm still open to suggestions. I'm doing my best to not think about the worst case scenario of loose bearing clearances. I haven't seen any indication that this is the issue, but all signs kind of point to it. I'll keep this post updated with any progress and I'll try any other suggestions people might have in the meantime.

 

[We're on Boost]

It would be pretty easy to "shim" the spring and preload it so it takes more pressure to open it.

Wait a sec - where did you put this shim? Most people, when they shim this spring, they are talking about putting thicker washers under the bolt head, which reduces the spring force on the piston. Can you show where you put your shim?

Your Speedhut oil pressure gauge - which sensor are you using for that? I see they make or have made their gauge 2 different ways. One way uses the A-124 electronic (3-wire) sensor. The other way uses the A-129 resistive (2-wire) sensor. I wouldn't want one of those resistive types. The one that uses the A-124 would be the way to go. Even the A-124 only costs about half of what the "equivalent" AEM sensor costs, so that might be a question. You could say AEM is overpriced but I don't think it's by that much.

Then there is the problem over time, that when you screw a pressure sensor directly into the OFH and you have balance shafts removed so the engine is a vibration apocalypse, that sensor gets hot and shook and it may or may not last very long. The sensor and it's location might not be your problem at all, but it's stuff to keep in mind. It's why I remote located mine. My brass AEM sensor got weird after a couple thousand miles screwed into the OFH. So I bought an AEM stainless sensor and remote located it.

I think we already talked about which port in the OFH to measure from? The numbers everybody uses are measured from a port before the filter. Unfiltered oil. Measuring after the filter will give you lower numbers. Like your turbo oil, that would be coming from a port after the filter (filtered oil).

I'm still getting readings of zero at warm idle, but they are weird numbers. It seems to jump between 0-12psi. It almost feels like it's electical in nature as I can hear the tone of the idle change. I'm sure idle is moving slightly, but less than 200rpm (likely 50-100rpm).

Is the tone going up and down in sync with the O2 voltage? Is it also going up and down in sync with the oil pressure reading?
I have that a little bit sometimes with my Talon and my BMW (which is completely stock) and I've tried to see it in my Talon's logs (looking to see if rpm is going up and down with O2 voltage) and it's not really jumping right out at me. The rpm variance isn't that obvious even though the tone difference is obvious. Your ear/brain is very sensitive to pitch and other tone factors when the changes are happening close together in real-time. So I'm not surprised when you say the rpm is only moving probably 50-100 rpm because you can hear even smaller than that. If you bring up an Online Tone Generator and flip back and forth between, say, 880 and 890 Hz, you can hear the difference. If you couldn't you'd never be able to tune a guitar or any other instrument without electronic help! Sorry about all that, I've always been an audio nut so I get into that stuff.

 

[DSMPT]

As I mentioned above that I think those are unlikely the direct cause of the low pressure issue in your case. In case if the porting or pressure relief valve was causing this issue, you should have had the issue from the beginning. Maybe you would be able to see a little difference by shimming under the pressure relief port spring (inside plug) with a small washer or replace the crush washer with a thinner one since I see you have a bit thicker crush washer than OEM. But that shouldn't affect the min side oil pressure much if all the pressure relief valve components are clean and working properly.

I am still wondering if you really have zero or almost zero oil pressure at OFH. For whatever reason, if that was true, you should have seen some sign of no pressure while the engine was running. Like hearing ticking sounds coming from the cylinder head. Technically you ran dry. I don't know how long you ran but yes that's bad.

Did you check if the oil was reaching to the rocker arms at cylinder #1 (under oil filler cap) while the issue was occurring? if you really had zero or almost zero oil pressure at OFH, you should have seen the oil was just seeping out from the rocker arm oil jet hole instead of jetting strongly, or no oil coming out from oil jet hole. If you see the rocker arm is jetting oil and if the oil reaches to roller bearing/cam lobe, then actually the oil pressure is decent.

 

[4G63510]

Lots of info to respond to, but here it goes.

I put a shim inside of the pressure relief valve "cap". I was attempting to increase pressure, not reduce it by adding a thicker crush washer. My EVO3 had a 1mm crush washer while the 2G unit had a 1.24mm unit. I stayed with the 1mm unit to keep pressure high.

I have tried both before and after the oil filter for sensor location, but both seemed to give similar readings. My sensor uses a "remote mount" -4AN line. Currently I have the resistor style sensor, since that is what I purchased 10+ years ago. Depending on my next results, I may switch to a more accurate 3 wire unit. I ordered a sending unit from Amazon and it should be comparable to the "genuine" SpeedHut unit.

I do not hear any odd noises like ticking or any signs there is no oil in the head. This is one of the things that is baffling me. If I truly was running zero oil pressure at the OFH, then there would be signs later in the oil's path that it had run out.

The oil pressure reading seems to follow the O2 readings fairly closely. I will take a short video that might help to show what I'm seeing.

I've done nearly everything I can think of to ensure that this car will run well and run for a long time. I'd hate to lose it to something silly. It's been flawless until the last year or so when I started seeing these things pop up. I'm still hoping it's a bad sensor or something easy like that. I've torn the engine apart 3 times to try and chase down and resolve this issue.

 

[4G63510]

Curiouser and curiouser. Before taking the car out to test things again, I went ahead and swapped the oil feed line to the sensor with the one to the turbo. (Opposite of this pic. Ignore the third sensor. That's an oil temp sensor in the outlet to the oil cooler)

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While driving and the car was about up to temperature and suddenly the pressure reading was all over the place. It hit zero during cruise at about 2200RPM. Then it went back up to about 40psi and swung a bit. It finally stablized.

When I got home and let it idle, it wouldn't drop below about 8psi and hung around 10psi+. It didn't fluctuate like it did yesterday. I still feel this is a gauge issue (I hope) but perhaps this location will read more accurately like others have stated. I don't see how it would be a 10psi+ change from the other location or explain why it fluctated so much.

On a side note, please ignore the grime under the car. That is from a previous oil leak that just hasn't been cleaned up yet. The car will get an undercarrage detail (at least for a 50yr old car) when I get this oiling issue sorted.

 

[danl]

This is starting to sound like a sensor/gauge issue. The oiling system is very mechanical. It isn’t intermittent like you are describing. It sounds like the sensor may be failing when it gets hot.

What DSMPT said about looking at the HLA’s through the oil cap is one good way to verify. If you are getting good oiling to there at hot idle you are in good shape.

 

[4G63510]

I installed a new sensor. I'm still not happy with the number I'm seeing at idle, but it never goes below 10psi when warm. I haven't gotten the oil temps up to even read on my gauge (140*), but I'm not seeing any odd numbers either. Cold idle pressure was much higher in the 85psi+ range and cruising pressure was much higher at well over 60psi. I will swap back to the EVO3 spring and plunger to see if that helps the top end at all or makes any negative changes to the warm idle pressure.

I guess I should have stuck with the old hot rodder mantra of "a gauge will show you if there is an issue, but if you don't have a gauge, you don't have an issue".

 

[We're on Boost]

I installed a new sensor. I'm still not happy with the number I'm seeing at idle, but it never goes below 10psi when warm. I haven't gotten the oil temps up to even read on my gauge (140*), but I'm not seeing any odd numbers either.

Seems like you are getting more sensible numbers with the new sensor, which is good.
But if your "when warm" is not even up to 140 deg oil temp, that isn't what I'd call warmed up.
Do you still have the pressure sensor going to that lower port on the OFH like you showed in post #38?
If so then where are you getting the turbo oil from?
Also, what is your warm idle rpm? That would effect what kind of pressure to expect at "idle".

 

[4G63510]

Seems like you are getting more sensible numbers with the new sensor, which is good.
But if your "when warm" is not even up to 140 deg oil temp, that isn't what I'd call warmed up.
Do you still have the pressure sensor going to that lower port on the OFH like you showed in post #38?
If so then where are you getting the turbo oil from?
Also, what is your warm idle rpm? That would effect what kind of pressure to expect at "idle".

My oil temp gauge does not show 140, its lowest reading, when I collected this data. My coolant temps are around 200. My oil temp sensor is located in the port leading out to the oil cooler. My cooler is a larger than OEM unit.
My oil pressure sensor was relocated from the above pic and swapped with the turbo feed. The turbo feed is now the lower line that is both post filter and post oil cooler.
I'll have to get a log to get an exact idle RPM, but it's around 800rpm. I think the factory setting is 750-900 with an oil pressure of 11psi if I remember correctly.

 

[1990TSIAWDTALON]

I get ragged on about this, but I don't trust electrical oil pressure gauges, I run mechanical ones. I tried 2 different electric oil pressure gauges, and they just wouldn't read correct at low pressure, like you are describing (and worried me). They would read close to zero when the mechanical gauge was at 10, 5 ish when it was 15. I went back to a mechanical gauge and I am happy to know what I see is the pressure in the line. I am old school and have always ran mechanical oil pressure gauges (and water temp on domestic motors) but to each there own. I haven't read back through your full thread, but did you try a mechanical gauge with the same results?

 

[4G63510]

I get ragged on about this, but I don't trust electrical oil pressure gauges, I run mechanical ones. I tried 2 different electric oil pressure gauges, and they just wouldn't read correct at low pressure, like you are describing (and worried me). They would read close to zero when the mechanical gauge was at 10, 5 ish when it was 15. I went back to a mechanical gauge and I am happy to know what I see is the pressure in the line. I am old school and have always ran mechanical oil pressure gauges (and water temp on domestic motors) but to each there own. I haven't read back through your full thread, but did you try a mechanical gauge with the same results?

I did try a mechanical gauge at one time, but I got similar readings as the electrical gauge. I was using a cheap gauge, so I didn't trust it nearly as much, but I used it to try and confirm my readings. I may try again at some point, but I'm satisfied with what I'm seeing now. I will likely upgrade to a 3 wire unit as someone suggested to get more accurate readings.

 

[We're on Boost]

I was using a cheap gauge, so I didn't trust it nearly as much, but I used it to try and confirm my readings.

You might be interested in watching the second video in post #60 in this thread from last year:
https://www.dsmtuners.com/threads/r...w-load-open-loop.543706/page-3#post-153891302

He was using a cheap oil pressure gauge with a scale from 0 to 100 psi, to read oil pressure from the port on the head.
Oil pressure at the head is a little lower than in the OFH anyway so it could be really low at warm idle with a low (stock) idle speed.
His gauge was dropping to what looks like 0 at idle. Hard to tell. Check it out at 20 seconds into the 2nd video. Anything below 10 psi on a gauge like this is a pure guess.
If he had had a 0-30 psi gauge instead of a 0-100, it would have been a lot better. But then you would probably overpressure the gauge on a cold start. So it's just overall not a good deal. You need a good gauge. Whether electric or mechanical, it needs to be a good accurate one.

I like the AEM electric gauges but here's the weird problem with them. The gauge kits they sell come with the brass sensor. There might be an option to buy it with the stainless sensor instead, but I don't see it. My oil pressure gauge is the AEM one and I used the brass sensor until it went weird. Then I replaced just the sensor with the stainless AEM sensor and remote mounted it. It works great and I log it as well as using the gauge. Since you are already remote mounting your sensor you might be ok with the brass type sensor. I think mine died because of all the heat and vibration it got being screwed right into the OFH. But the stainless AEM sensors are very good. PSIg type for oil pressure. Not PSIa.

 

[We're on Boost]

While you are in that other thread (crazy knock) scroll down to post #65 and look at that video too.
In that video he takes the oil fill cap off to watch for oil flow inside while running at hot idle, like people are suggesting in this thread.
He got a lot of oil flinging around and that was with the same "zero" oil pressure at the head.

Then look also at post #64 over there. He says "Testing the oil (pressure) gauge with compressed air shows it won't register anything until somewhere between 5 and 10 PSI" (that was the Summit Racing 0-100 psi mechanical gauge). But then of course we don't know how accurate his air pressure gauge is either. Probably not very !

 

[dwb]

Then look also at post #64 over there. He says "Testing the oil (pressure) gauge with compressed air shows it won't register anything until somewhere between 5 and 10 PSI" (that was the Summit Racing 0-100 psi mechanical gauge). But then of course we don't know how accurate his air pressure gauge is either. Probably not very !

I'm the OP on the crazy knock thread. Indeed my compressor regulator gauge wasn't very accurate but I also used another not-so-accurate gauge as a second data point. I also used my mouth to see if I could move the needle on the oil pressure gauge, and I could not (that's probably 2-3psi).

 

[We're on Boost]

I'm the OP on the crazy knock thread. Indeed my compressor regulator gauge wasn't very accurate but I also used another not-so-accurate gauge as a second data point. I also used my mouth to see if I could move the needle on the oil pressure gauge, and I could not (that's probably 2-3psi).

There is a lot of really valuable stuff in that whole thread. You wouldn't believe how long it took me to find it again though. I thought I had it bookmarked with every key word possible but I didn't. I thought it was really recent like 2 months ago but actually it just went for a really long time before ending in September. Well now I have it bookmarked with every keyword imaginable. I hope.
Anyway, good thread!

 

[evil_eagletalon]

Question. When you buy your wix oil filters do you ignore the part # it lists for a old school 4g63? The reason i ask is because on my 1g it called for a p# they didnt stock so in my head i said well a evo 8 shall work and they had that in stock.

 

[We're on Boost]

Question. When you buy your wix oil filters do you ignore the part # it lists for a old school 4g63? The reason i ask is because on my 1g it called for a p# they didnt stock so in my head i said well a evo 8 shall work and they had that in stock.

The oil filters made for the Evo 2003 - 2006 and for the Talon/Eclipse after 1992.5 have smaller gasket OD and ID than the oil filters made for Talon/Eclipse 1990 - 1992.5
Plus they have a smaller internal volume which you already know.
But the Evo filter relief valve opening psi is about the same (around 14psi), and that is important, I mean you don't really want it lower than that.

So for example, English Racing gave my car back to me with the new engine in 2016 with an Evo8 (K&N HP-1004) filter on it.
When I took it off to change oil almost a year later I noticed the gasket had a step right in the middle of it where the filter gasket miss-matched the land area on my 1990 OFH.
I measured across that step in the gasket roughly with a tape measure and here's what I sketched at the time:

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Pretty ugly gasket fit but it worked.

The Wix filter made for the 1990 - 1992.5 is the 51381.
It has proper gasket ID and OD to fit right in the middle of the 1990 gasket land. The relief valve is rated 13 - 19 psi (good). And it's a bigger filter than any of the others. So that's the one I buy. I don't see them in local stores anymore so I buy them from Rock Auto, which does a proper job of packing them (in a decent cardboard box, not a fricking bag), has low price, and has them in stock.

Here is a more accurate measurement I made just now of the ID and OD of the gasket land on a brand new 1990 OFH (MD132912) that I bought last year from Amayama. What I show as 2.25" in my old sketch is actually 2.210" on the OFH:

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I don't know if the 1991 and early 1992 OFHs measure the same here.

​

And now for the filter gasket ID and OD. That is shown in the Wix filter lookup.
Here's for the Evo 8 & 9 filter, the 57092:

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And here's for the 1990 - 1992.5 Talon/Eclipse filter, the 51381:

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[4G63510]

That's good info. I do in fact run the Wix 51381 filter as well. I get them at a local O'Rielly store. I have always used the larger filter, as in my mind, it has more filter surface area. I had no idea about the gasket or the opening pressure. This might be something to look into in the future.

 

[evil_eagletalon]

Good info it was just a thought that came to mind since i used a evo 8 filter.