Your oil pressure trace is very concerning. Are those dips down for real? Based on the data trace, I'd say it is, unless you've got a lot of smoothing on that channel. That is, unless you're fine with what looks like <15 psi of pressure at idle. I'd personally bump up my idle before subjecting the engine to that little pressure.
Last edited by Def; 08-01-2017 at 11:29 AM.
10-12psi is typical M5x idle pressure
You guys are hilarious.
Some of those drops are because there is ZERO engine speed.
Also, the oil pressure scale starts at 20 PSI.
The RPM is actually pretty steady at 2:30; 850 RPM.
The issue is oil temp with 20W50 oil, where it's holding 70 PSI at idle, then the valve will cycle open dropping pressure to 50 PSI, spiking briefly to 80 PSI, before settling back to 70 PSI. The pressure relief valve, and this oil pump, simply wasn't designed to operated like this. (Heavy oil)
I started the car at 67 deg F, and at 2:30 it is at 80 deg F. Once the oil gets up to about 160 deg F, oil pressure is very stable. Idle is at 850 RPM, and I have 20 - 22 PSI of oil pressure.
One variable that I've been working with since 2009 on my car, that nobody else on here has, is billet oil squirters. They have no check valve, so in theory, I should be seeing lower oil pressure at idle. The race engine I ran in 2009 had 15 PSI oil pressure when hot. My current engine will see 15 PSI briefly if idle drops to 800 RPM.
This will shock people, but I'm also not running a synthetic oil....as I seem to pull my engine apart before I hit any reasonable oil change intervals. I do have 11 quarts of oil in the system though....so that's another variable that's different from most.
I've been looking at this data for 2 years now, and bouncing stuff off a guy that has tuned a lot of engines at a very high level.
There were things that I was concerned about, because I had a very clear and high resolution signal trace, that I learned to be very normal. Most of the time people are used to seeing averages of a sensor across 10 or more data points, or the sensor's ability to measure change is in seconds vs milliseconds. When you start looking at a sensor trace 100 times a second, versus 1 time a second, you think you're seeing all kinds of problems. Fuel pressure is a good example. Depending on proximity to the fuel rail, it can have a lot of noise in it. Fuel pressure can also be caused to oscillate due to the size and length of vacuum line to the FPR. There are lots of variables that I'm learning about....
One of my current data mysteries is fuel pressure. At 15-16 PSI of manifold pressure, it holds steady at 70 PSI on a static base pressure of 58 PSI. Injector duty cycle doesn't ramp up dramatically, the lambda target holds, and total fuel flow is well below the fuel pump's capability. My theory is that either the FPR or the Fuel pump have maxed out pressure wise, but not on flow capability. I'm contacting Aeromotive to see what they think....
The Aeromotive regulator should be able to do a base pressure of 58 psi, and I don't think there's a limitation for the rising rate, as that's just pressure across the diaphram. I will say that my regulator out of the box had a super leaky pressure port fitting. The regulator spring is right behind the port, so you can't just screw it in more. I think I used some green loctite on the fitting to really seal it up, as it'd slightly bubble with even 3-4 wraps of teflon tape on it. It was 1/16" NPT IIRC.
As for a noisy fuel pressure signal, that is real, and it's not necessarily "normal." You can run a fuel pulsation damper. More and more OEMs are using them on cars. Here's a nice aftermarket solution: http://www.radiumauto.com/Blog/Post/...lse-Dampers-90
The double sides sword of good data. You see all these cool things, but you also see a bunch of things that dont make sense either.
328i Sedan Twin s366's, 6.0LS, TH400, MS3 Ultimate
9.20 at 150 on 22psi
I was involved with a nitrous pro-mod program from 2008 to 2011. It was using a MASSIVE wet single stage with PWM control, and there was a LOT of work being done on the fuel pressure side. What was learned was that you didn't just need "a" damper, you needed one tuned to the resonant frequency of the fuel circuit. There were a few different iterations tried before it was "right". The Radium one I suspect is tuned for the S54 fuel rail and fuel system.
You can see the damper mounted to the end of the fuel rail in the image below with a very high resolution fuel pressure sensor on the bottom. (It was like $500 IIRC?)
You'd want to do an FFT analysis of the fuel pressure trace to see if there was a problem. We found that the issue was in the frequency domain, not in the time domain....
Last edited by PEI330Ci; 08-03-2017 at 09:40 AM.
Why would the Radium damper be tuned for an S54? It's more often used on Japanese imports than anything else...
I don't really agree it needs to be perfectly tuned for a system either, as providing a much more compliant accumulator (which is what it does) is naturally going to smooth out fast pressure responses, regardless of its natural frequency. I would also argue the compliance of the accumulator reservoir is so soft that it is likely VERY FAR from the natural frequency of the fuel injector pulses, even at idle.
My very rigid PTFE hose and hardline fuel system got a huge amount of resonance between the 2-5k RPM range, and above that it was likely getting smoothed somewhat from the sensor response time. The same system with a lot of rubber lines in it was nice and smooth all over. OEMs started using a lot of fuel pulsation dampers when they switched from plain rubber fuel lines to the low permeability type hoses in the early 2000's.
tldr; Natural freq of pulsation damper is likely so far away from excitation freq of system that there is no concern.
I like nitrous and pro mods.
328i Sedan Twin s366's, 6.0LS, TH400, MS3 Ultimate
9.20 at 150 on 22psi
Detailed look at oil pressure:
There's nearly 70,000 samples of oil temp, across 2 driving sessions with I've overlaid to show consistency. I have filtered the values based on temp, which you can see on the legend on the top right. I can overlay lots of files...but you get a sense of the trends from these 2.
From this data, I then populate a slightly modified oil pressure warning system in the M1 ECU:
If the oil pressure exceeds the low or high value limit, the oil pressure alarm triggers. Then, if the alarm is active for a duration of my choosing, I can limit engine RPM to a set value. In this case, I've chosen 2000 RPM, and the alarm triggers the SLM to flash red at me.
Last edited by PEI330Ci; 08-03-2017 at 11:24 AM.
One more for fuel pressure:
Fuel Current = Lift Pump + Main Pump + Injectors (Total current draw of fuel system)
2 log files over-laid.
I'm going to try a lighter weight oil, probably a 5W40 Motul 300V. Will be interesting to see how it shifts the pressure/temp signature....
Just set up the fuel and oil pressure channels to be able to log at 1000 hz.
If anyone reading this has a Motec M1, you won't be able to do this unless you have 2 things:
1.) Logging Level 3
2.) Development License
The default oil logging rate is 10 hz. You can reduce this frequency in M1 Tune, but you can't increase it. To go from 10 hz to 1000 hz sample capability, you have to change in M1 Build both the sensor input logging rate, and the update script under the pressure group.
Fuel pressure is limited to 100 hz logging from Motec, so you have to do the same thing to that channel.
What kind of extra info do you think you'll be able to get by logging oil pressure at 1000 hz vs current rate? And can you put 1000 hz into perspective as far as how fast/slow it is compared to the frequency you are using to log most other sensors?
Do you think your transducers are going to give good information at 1000 Hz? In my experience, you need some pretty fancy stuff to actually get usable/accurate data at that rate.
I can't see any good reason to look at pressures at 1000 Hz at all.
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