Low oil pressure after WOT

[pogman]

So recently at the track had experienced a loss of throttle after a period of WOT after installing the emtron ecu, recently did some logging to troubleshoot the issue and found the ECU was cutting due to a low oil pressure issue. Going over the log can see that while accelerating at 4k rpm will see 100 PSI of pressure and holding steady at that level until getting off the throttle which then after can see as low as 25 PSI at 3-4k rpm and will recover back to a normal level after that.

 

Wondering if anyone has an idea what could be the cause as it just feels abit strange and i dont feel like it could be a sensor issues just due to it clearly sitting at a good pressure until off throttle, in the attached can see a 3rd and 4th gear pull but can even perform great through 3 and 4 gears of WOT but still once off throttle and getting back on it will see pressure drop.

[wardiz]

where is installed the oil pressure ?

[pogman]

oil pressure sensor sits on the filter block, i believe after the filter but i may be wrong about that.

[Dose Pipe Sutututu]

As in an oil relocation block away from the motor?

This "may" be the cause of the inaccurate oil reading, however that's the same excuse I'm using with my shit box too lol.

On WOT you'll see a good 6 to 7bar of oil pressure and lift off, it drops to under 2 bar tripping the engine protection.

[Duncan]

In those logs are you on a track (ie braking when the oil pressure dips) or on street/dyno etc. You might need baffles in the sump.

Alternatively.....turn the oil pressure protection down to 1.4bar?

[pogman]

4 minutes ago, Dose Pipe Sutututu said:

As in an oil relocation block away from the motor?

This "may" be the cause of the inaccurate oil reading, however that's the same excuse I'm using with my shit box too lol.

On WOT you'll see a good 6 to 7bar of oil pressure and lift off, it drops to under 2 bar tripping the engine protection.

It's plugged into a grex sandwich plate so it's still bolted onto the motor.

 

Interesting im glad I'm not the only one to experience this then ahahah

[pogman]

2 minutes ago, Duncan said:

In those logs are you on a track (ie braking when the oil pressure dips) or on street/dyno etc. You might need baffles in the sump.

Alternatively.....turn the oil pressure protection down to 1.4bar?

In those logs I'm on the street but I did have to brake pretty hard, I had tried it where I also didn't get on the brakes too much after and still experienced the same issue. The sump has "some" baffles but I'd say it's fair to say not enough.

 

I would agree with you and just turn down the oil pressure protection at least for now, but was interested to hear some opinions as I couldn't find any info on the problem.

[Duncan]

Yeah well I was thinking...there is nothing that happens when you get off the throttle that should cause low oil pressure, its not like clearances suddenly change or and the relief spring would close and in any case the sensor is on the feed side....so more likely there was no oil available to pick up

which means all the basic oil control stuff to:

1. keep oil out of the head (restrictors)

2. get it back out of the head when it gets there (external breathers/oil return, drilling out the block and head oil returns)

3. have more oil in the sump to pick up - larger capacity sump

4. have more oil near the pick up - baffles

[Duncan]

speaking of the relief spring and noting this is one of those stupid times where I understand imperial (psi) but the graph is in metric (kpa), it looks like the oil pressure is a little low at full noise too, isn't the relief spring 120psi/830kpa?

[pogman]

7 minutes ago, Duncan said:

Yeah well I was thinking...there is nothing that happens when you get off the throttle that should cause low oil pressure, its not like clearances suddenly change or and the relief spring would close and in any case the sensor is on the feed side....so more likely there was no oil available to pick up

which means all the basic oil control stuff to:

1. keep oil out of the head (restrictors)

2. get it back out of the head when it gets there (external breathers/oil return, drilling out the block and head oil returns)

3. have more oil in the sump to pick up - larger capacity sump

4. have more oil near the pick up - baffles

It certainly does make sense that there is just no oil to pick up, but I can go 3 or 4 gears of WOT and have no oil pressure issues too (I have no logs of this unfortunately) and I have a fair amount of oiling mods to try and help only thing I'm missing is a rear head drain which is potentially the most helpful. 

[pogman]

8 minutes ago, Duncan said:

speaking of the relief spring and noting this is one of those stupid times where I understand imperial (psi) but the graph is in metric (kpa), it looks like the oil pressure is a little low at full noise too, isn't the relief spring 120psi/830kpa?

I also understand psi but apparently most things make more sense in kpa oil pressure being one of a few exceptions so im trying to learn ahahahah, I have no idea of the relief spring pressure tbh I thought 110 which is the absolute peak it hits was about right, I was thinking of removing the relief and making sure it is in good condition, I would just replace it but couldn't find a replacement for an n1 pump too easily but I could just be blind.

[Dose Pipe Sutututu]

1 hour ago, pogman said:

plugged into a grex sandwich plate so it's still bolted onto the motor.

Well that rules out the relocation theory, however with no load, you're still getting 1.5bar of oil pressure.

Can you present that data in a scatter graph over longer period? Would really highly the anomalies.

Wish Haltech could do that.

[MBS206]

Can you log battery voltage, and TPS, and put all four of those into a single image (even as split graphs)?

 

The oil pressure drops aren't following RPM as such.

I'm intrigued if you may have a ground loop between different sensors.

With the engine not running, log your sensors and for example cycle the throttle pedal. See if any sensor values flutter or move about. This won't be a perfect test either as the ECU won't be cycling all of its actuators like it would be while running.

What EMTRON do you have? Do you have a link to the wiring guide for that ECU?

[MBS206]

You are also getting pressure dips on gear shifts.

They're just not dipping as far, but they're dipping quite below the amount of oil pressure you should be seeing, for how much RPM drops.

 

It quite little could be the oil pressure relief valve is starting to stick open a little/is slow to close.

[Duncan]

1 hour ago, pogman said:

I also understand psi but apparently most things make more sense in kpa oil pressure being one of a few exceptions so im trying to learn ahahahah, I have no idea of the relief spring pressure tbh I thought 110 which is the absolute peak it hits was about right, I was thinking of removing the relief and making sure it is in good condition, I would just replace it but couldn't find a replacement for an n1 pump too easily but I could just be blind.

Yeah so N1 and any other larger than factory pump are pretty famous for pumping the sump dry...obviously we don't often get to spend 20 or 30 seconds at high rpm/full noise on the road so I'd still be suspicious that is what is happening here.

[GTSBoy]

Log voltage. I'm suspecting the alternator.

Or even maybe a bad earth somewhere.

ie, seeing as it is rev dependent, I am thinking it is alternator dependent.

[Kinkstaah]

Get more oil pressure sensors. I have 3 purely because trust no-one.

It would be worth checking (if not already) if it happens on every shift. Like boring, 2-3 shifts at 60kph making 10kw with no obvious G-force on a shift with mega power. Does it still drop? Does it drop less?

What if you shift at 5000rpm or what have you with no load?

[MBS206]

2 hours ago, GTSBoy said:

Log voltage. I'm suspecting the alternator.

Or even maybe a bad earth somewhere.

ie, seeing as it is rev dependent, I am thinking it is alternator dependent.

It doesn't seem to follow revs. Oddly it seems to follow TPS a little bit from what I can see, but with some delay a bit.

IE end of the graph, when he lets off throttle fully, pressure drops a lot, then slowly builds back up, but rpm is on a nice cruisey drop off.

I do agree though, it seems very electrically.

[pogman]

10 hours ago, Dose Pipe Sutututu said:

Well that rules out the relocation theory, however with no load, you're still getting 1.5bar of oil pressure.

Can you present that data in a scatter graph over longer period? Would really highly the anomalies.

Wish Haltech could do that.

im surpirsed a halaltech doesnt show that. this scatter is from a 45 second long log

[Dose Pipe Sutututu]

3 minutes ago, pogman said:

im surpirsed a halaltech doesnt show that. this scatter is from a 45 second long log

Definitely looks like an outlier, perhaps there may be some electrical issues like others have pointed out earlier.

My pressure drop I can replicate over and over again, which I'm blaming the relocation block for, however yours is mounted right up the block.