2014 Audi A4 low oil pressure and rough idle
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- čas přidán 20. 08. 2020
- Let me know if you have a different theory or testing method that will prove of disproove my theory.
Question: Does excessive vacuum in the crankcase reduce oil pressure.
Research or supporting argument:
1. Oil pump creates a low pressure area(suction) in the pickup tube as the engine spins causing oil to be pushed up the tube by because the pressure in the crankcase is higher than the pressure in the tube(sucking the oil out of the pan)
2. The crankcase pressure will apply even forces(within reason) to all areas of the crankcase.
3. the oil pressure sensor or switch including our test equipment is a relative pressure comparing ambient air pressure to the oil pressure in the oil galley.
4. Other characteristics of the engine, variances and environmental conditions will make exact comparisons difficult.
Hypothesis: Oil pressure inside an engine remains the same under vacuum conditions even if the gauge reading indicate low oil pressure.
Experiment: measure oil pressure on fully warmed up engine at idle and compare results to same engine with lower than atmospheric pressure condition (Vacuum) applied to the crankcase. Easy for us since the fault on this engine is reducing the crankcase pressure below atmospheric pressure(vacuum in the crankcase) We will compare the oil pressure to the pressure in the crankcase and see if the change in oil pressure is the same as the change in crankcase pressure.
Results: The pressure did change about the same as the pressure applied to the crankcase. Without a more controlled environment we cannot gain more accurate results(bonus footage at the end has the closest measurement between crankcase pressure and oil pressure)
My thoughts: auto manufacturers would have to have a crankcase pressure sensor installed and use an oil pressure sensor instead of the switch commonly used in order to accurately display oil pressure conditions to the operator. This is too expensive for the results since crankcase pressure is normally +/-1psi and only exceeds those value when a fault is present.
Next question: would high crankcase pressure increase oil pressure reading relative to atmosphere.
Another question: If a pump including its inlet and outlet was situated in a complete vacuum(absolute pressure 0psi) would the pump be able to pump? Without the ability to create a pressure differential how can it draw fluid into itself. If this is true can we have an efficiency loss in the vehicle tested with vacuum in the crankcase because the pump may be creating a lower pressure differential? - Auta a dopravní prostředky
I have to say CZcams is a hell of a thing. I absolutely LOVE problem solving videos like this. Most people will find this boring, but the rabbit holes that you have to go down to focus on on the cause of the problem is fascinating
I can confirm your theory is correct, while I'm not a mechanic I do have some mechanical experience as I do everything myself on every car I've ever owned (except for things like wheel bearings and things that require specialized tools). Last week I had the dreaded 'Low Oil Pressure, Switch Engine Off Immediately' on my A5 2.0T, that is a scary warning, so I shut it off right away but I still had to get home (I was maybe a half mile from home), so I limped it home, shut the car off each time the warning would sound (which only came on at idle when stopped at a light) so that was my first clue (strangely it didn't throw a code, or at least the CEL didn't come on). Once home I let the engine run for a couple minutes while I looked around under the hood, I noticed when I went to open the Oil cap there was so much vacuum suction in the crank case I thought I was going to break something if I yanked it off, so I didn't, also I noticed there was no extra rattling or worrying sounds coming from the engine as it ran, so those were 2 other clues. I saw your video here shortly after (that evening or the next morning) and deduced from those 3 clues that maybe, just maybe it's the PCV diaphragm is torn, so I ordered a replacement off Amazon incase I broke it while checking it. So I tried to open it without breaking the PCV cap but of course it broke, and to my pleasant surprise the diaphragm had a small (half inch) tear in it. So I ordered replacement 'low oil pressure and high oil pressure switches from Audi incase it was that, but low and behold the $20 replacement PCV cap and diaphragm arrived, so I switched it out and problem solved, that was it. I didn't want to say that was it right away so I waited a week and tested it by daily driving, put about 400KMs since and nothing, now warning, no funny sounds from the engine bay, nothing, so I think it's safe to say that yes your theory worked (in my case at least), thank you for the video, keep it up!
Thanks for writing up you experience with this same issue. Ever since the B5 passat and A4 with the 1.8t had the dreaded oil light while driving down the road we get a little nervous when it happens to any vehicle. The 1.8 would sludge up the sump and actually starve the engine of oil but from my experience the 2.0 suffers from excessive vacuum more often than actual low oil pressure.
Now don’t get me wrong the 2.0 has its share of oil pump issues and oil pressure control valve issue but the pcv system is checked first from now on.
Thank again for sharing.
I am going to try the same. My car has the same issue. I have an Audi A4 B8 2.0T. Would it be wise to buy the whole PVC valve plus the whose that comes with it? Thanks
@@JoseStudios it's just the PCV valve cover that develops a little tear in the thin liner inside, once that happens it creates crazy vacuum inside the engine, the PCV valve cover is only maybe $20, but it's an easy test to see if that's your issue, try opening the oil fill cap while the engine is running and if it has a lot of resistance and is hard to open then that's your problem.
Thanks for the sneak preview via the chat. I follow your theory, but only because of your explanation and knowledge of how that "system" works. Showing the results on the scope was cool.
It made since in my head and was trying to find the best way to explain it. I hope with the scope captures and the description I typed up I was able to explain it fully.
@@ThePracticalMechanic is it enough to change the valve or better the full unit ?✌️
Great video Chad! I remember you talking about this but didnt realize that the video got posted! This was a great lesson!
Very interesting theory. Never thought about that before this. Very well explained and the testing process was intriguing. Very scientific 🤓🤓
I had these exact same symptoms with a rough idle at low RPM, with a low oil pressure warning. This is a common problem with Toyota Corollas, Matrix, or Vibes about 5 or 6 years old. Either the PCV well simply wear out, or the PCV hose will crack, creating a vacuum leak. So at idle the low oil light will start flashing. But goes away once you're above 1500 RPM.
That little episode taught me to change my PCV and hose at least once a year.
Very informative. Great explanation. Thank you 👍
I also read the description and i am inline with your comments that why the manufacturers put switches instead of sensors!!
I love this guy!!!!! He saved me so much money!!! Like he said change the PVC!!!!!!! (((Low oil pressure switch off engine))) I will say it again change the PVC!!!
Awesome!! Glad it fixed the issue. I’ve since seen many VWs and Audis come in that already had the oil pressure switch replaced or the oil control solenoid replaced and the light still comes on. Quick crankcase vacuum test to find out if I need a crankcase regulator and done.
Thanks for watching and commenting your results.
My man! Shall have been an engineer! Or technical support! To make money become an expert on something like! Only Bentley, Porsche, Audi, Vw! They all use similar tools and owners pay good money when you know this much! And remember never cheap out on parts on these cars! You are pure brains! This part was updated several time for this same reason
Awesome video! Very interesting and good find
Thanks for the informative video.
Just wondering on oil pressure switches in Skoda superb, there are two, as you also mentioned. F22, F378 where the later one is mounted on top(brown) and F22 is blue below that. I am wondering they are just a NO contacts and when i checked with DMM. really needs to push a bit hard to get contacts closed. I am not sure and ithink this design could have flaws as a little lower range of pressure can make the switches to deactivate. Again I am not sure about this digital information to dashboard. My oil pressure is showing low intermittently and no mechanic so far understood the issue here. Engine seems ok, No noise. I think your video makes sense. Please advise me if i have to check the vaccum.
Brilliant discussion, I think you're right, the reference should be relative to crankcase pressure. We use oil pressure to estimate the delivery of oil volume. Kinda like using voltage to infer total current or power delivery, different things. If one could measure volume of oil pumped it might be a more accurate, but then again to interpret readings one would need a table to cancel the effect of higher pump rpm. These pumps are volume driven so absolute pressure of the liquid shouldn't matter much, especially when the outlet is subject to the same pressure effects inside the engine.
I’m going to have to build a test tank with built in pressure and flow sensors to completely prove or disprove my theory but I think the flow will remain close to the same. At higher levels of vacuum we may see a decreased flow because the pump won’t be able to create as much of a pressure differential and will be unable to draw in the oil from the sump.
@@ThePracticalMechanic sorry to tag but I’m new to this stuff. I attached a catch can and a breather filter on my 2.0t and was gonna try doing the dip stick vacuum test. Wondering what I should look for numbers wise and any tips on what to do while. I had an issue during winter month before the breather were oil came out of the cap. So now I am just curious to know how everything’s working now. Appreciate any help.
@@koncretesurfer5295 the best way to test the crankcase vacuum is with a millibar pressure sensor but a regular vacuum gauge can be used for a quick test. I like to see less than 1in/hg when measuring at the dipstick. If using a mbar sensor you will likely get a reading of 30-50mbar.
@@ThePracticalMechanic dip stick didn’t move at all. I instead inserted it into the manifold were I have it plugged from installing the catch can. Does this seem right? When I did so it read on the green around 50. Seems correct but weird nothing happened with the dip stick. I assume because of the catch can. Appreciate any input as I am still learning and I enjoy knowing more.
Hi, nice and informative video. Thanks for the knowledge with us. Whether this will be applicable for diesel vehicle also?
Thank you for making this video
Thanks a lot man 😀😀😀 you are star ....... I've changed the oil pump and both pressure sensors but the problem persisted when the engine was at optimum temperature 🌡️...... I've just replaced the pcv and booom problem solved 🙏😀😀
Can someone help, I have a 2.0 Tfsi A5, it came up with the oil pressure to low message on the dash and it now idles rough and when the car is coasting it builds up revs by it self, have had engine oil and oil filter changed mechanic now thinks replacing the switch will resolve the issue
Same issue with 2013 A4 and only 99km on engine. Replaced switch and PCV and no change. Audi mechanic foreman suspected something more going on with end bearings so inspect screen in oil pan for metal shavings or cut open filter and inspect.
i have a rough idling vw cc 2.0tsi ccta engine. Low oil pressure light flashes when hot and mechanic has verified low oil pressure.. Would it be worth it to replace the pressure control valve to see if it helps? im misfiring above 1/2 throttle and replacing coils myself soon and pcv if anyone thinks it would raise oil pressure.
That's a lit video bro!!
I wish many can understand how sometimes simple it is to diagnose low oil pressure light. Oil pressure switch (Brown)and sender(Blue) hardly cease. The only problem are in the oil filter housing and PVC, as funny as it may sound, I fixed many A4 1.8 or 2.0 B8.5 and B9. Unfortunately I am in South Africa, I drove 1052 km and it never flashed.. The problems are seals or PVC diaphragm . Even oil pump for those models hardly fail.
Wow thank you my brother🙏🏾
Where are you located, my car has this problem but the mechanic said it’s the two switches, changed them but the problem is still there
@@dumisanimgqoboka6934 Otherwise it is very scaring when it indicates that you should switch the engine.. Do not drive more than 100 miles
@@phlubi1223 very scary, I never drive except 5 min to the shop & back. I want to try check PVC diaphragm & seals cause it does show some leaks
@@dumisanimgqoboka6934 Buy Oil Filter Cap it comes with a seal on the pointer and buy a new oil filter it also come with a seal. You might as well do oil change. Then buy an engine oil cap. Buy both Oil filter and engine oil cap at Audi Dealership whereas oil filter and engine get them at Goldwagen. I prefer 5W 40 Helix Ultra, it's not recycled but natural hence the price. Thereafter switch on the engine then clear the fault codes prior and after..
and what is the problem with diesel? with oil pressure?
Thank you Chad. Good job. Pressure is a result of the amount of flow and the resistance to that flow. Yes, vacuum inside the crankcase (on top of the oil) causes the oil pump to draw less oil in and results in less oil flow out. So it reduces the volume of flow. Less flow results in less pressure. Same effect would occur in fuel tanks. If the empty space above the fuel was allowed to be drawn into a lower pressure (vacuum). It would result in less fuel flow and lower pressure.
Have a blessed and safe week to you and your family.
The vacuum at the inlet of the pump are the same as the vacuum at the outlet, so it does Notting to the pressure as Chad said, but it does infect the oil pressure gauge comparing to atmospheric pressure. The vacuum valve controlling the vacuum are faulty. New vacuum valve, vil fix the high rev, and give a correct reading of the oil pressure.
on the fence with this one...i think it is flow , literally pulling on the oil causing low oil pressure and not difference in pressures from the sensor but would love to find that out for sure. If that vacuum is able to pull on crank seals , imagine how easy it would be to pull on liquid. A vacuum cleaner test in a bowl of oil should be a good lab test.....ha ha see if it spills faster while you have the vacuum in the bowl. Why is it harder to pull the OIl Cap off ????????Oil pump is having the same problem.....
Awesome. Thanks
great analysis, well change oil, PCV. problem solved.
Quick one, I know this thread is old but I am having this issue whereby the “reduce oil pressure switch oil shows as a fault
Code and it asking me to top up oil, by showing the oil can, now I had the oil pump changed, but still low oil info still shows. My pcv os mot sucking air from the outside though it tiny side hole into the crankcase but I notice that I have high suction when I open the oil cap cover when the engine is idle, and when I open the oil cap, the engine begin to surge or have rough idle but when I close it, it won’t exhibit rough idle but I have high suction, please tell me do I still need to change the diagram of the pcv
Any update if change of the PCV valve solved the issue with to much vacum in the crankhouse?.
Johan Falkman yes. Replaced the crankcase pressure control valve and everything went back to normal.
@@ThePracticalMechanic where is that located? Thanks
@@ThePracticalMechanic sorry, figure it out. Thanks!
Does anyone know if someone has a detailed training video on using the pico. Im not good with reading and applying certain directions. I can use the scope but thats where it ends for me. I dont know what or how all those other functions work. Basically i just get a signal and thats it. Im not new to scopes but im not old ether if that makes sense. I would like to get better.
Although it’s not picoscope exclusive I just started a labscope training series. We are starting with some common tests and waveform acquisition. I will be doing some pico oriented videos in the future. Are you looking for information on custom probes and math channels like what I used in this video?
@@ThePracticalMechanic yes exactly math channel and any other extras it does. I just have a hard time following and understand directions when im not knowledgeable on the topic at hand. For example it will say something crazy like, "switch the flux capacitor to 15 degrees and dual processor to B" then all the sudden im lost. I have to stop look up flux capacitor then daul processor see what thats all about before i go on.
@ThePracticalMechanic but ill keep my notifications on because i really want to up my diag scope game. After watch WELLS youtube channel on evaps systems for bwm and Chrysler it blew me alway. I learned so much. Ive always been a type of person that wants to know how it works the whole system. I was never satisfied just knowing this switch controls that. I want to know how and why. I love doing diag work because im constantly learning. As soon as i think i have a system licked they come out with something new.
I'm going live tonight to discuss the weekly waveforms and I'm including some basic picoscope match channel information. It will be available afterwards if you miss the livestream
Great vid....where did you get the specs for pressure btw?...Thanks
I don’t remember on this one but I use Prodemand, alldata and identifix daily.
The switch also has the pressure stamped on the side that the switch opens/closes.
hi i need your help if you can pls i have audi a1 2011 ofter 10 min drive message coming stop switch off engine oil pressure too low. soo far i have changed oil pressure switch twice same issue changed oil pump new still same. changed oil level sensor still same, changed pipe sucks oil fresh serviced please if you can help only lights come on after 10 to 15 min drive
Did you ever get a fix on this? Having the same issue on vw t
Awaiting a response from a professional....
One is for the oil pressure and the next is for the switchover of the two stage oil pump!
I have an Audi A5 2011 I have this problem my car is actually misfiring & rough idle & the low oil pressure light keeps coming on . I got full tune . New timing chain kit new high pressure fuel pump sensor new connectors my car is still rough running & Mis firing . Could it be my pistons going bad or what should I do I been spending tons of money
It could be all sorts of things but in the video I show what testing I did for the low oil pressure light issue. Your issues sound different than my issues but the problem may be the same. You may want to have someone check the crankcase regulator.
I have the same car with low oil pressure. It happens in different situation than mentioned, tl;dr it only comes after the oil is hot (like in the video), but only in D (idle), if I put the car to N/P after the light comes up then it disappears after a second or two. Could it be still the PCV?
I'm having this very same issue, oil pressure low only after the engine is up to operating temp and only in drive. What was the issue with yours?
@@ChrisKellyPrime How long have you had yours and have you tried the pcv solution
@@FelixObuya I've replaced the PCV, but no luck there. I took it to a VAG specialist and he thinks it's the balance shaft. I'm currently having the engine swapped.
@ChrisKellyPrime hey i would love to hear from you...did you ever find the problem or find out what was causing it???? I'm still having this problem after a engine swap and a rebuild engine that was swapped still low oil pressure😢😢😢
@@coryjackson6034 My solution was to sell the car.
Did the low oil pressure appear on idle or on revs? Got one low oil pressure light on hard pulls and havent started the car since :D
This was at idle.
I have the same problem.... but don't have a vacuum leak.... 10psi at idle hot..
So what is the fix/problem?
For this vehicle we replaced the crankcase pressure regulator. The excessive vacuum in the crankcase was causing a false low oil pressure reading from the sensor.
I changed it but didn’t fix my problem
This mad i have a golf r driving me mental hope this is my issue
So what was it after all?
The crankcase vacuum regulation assembly was applying too much vacuum to the crankcase causing a false oil light.
@@ThePracticalMechanic jeśli bym przeniósł przewód zasilający odmę przed filtr powietrza? Zainstalowany przewód byłby skierowany w kierunku przeciwnym do zasysania. Podciśnienie byłoby mniejsze bo wlot powietrza w pasie przednim jest szeroki. Opary że skrzyni korbowej także były odprowadzone. Myślę że w takim rozwiązaniu membranę w odmie należałoby usunąć.
Pcv valve.. Replace to updated unit
This should be a good one... What is it with German cars and low oil pressure 🤣
You soke
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