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Tigra Twintop 1.8 AT Z18XE AF17
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Discussion Starter · #1 ·
70.000 miles, helping a friend.

Story is after oil and oil filter change (take a bit grain of salt), this error pops up in the dash after 3500 rpm. Distribution chain found loose, replaced. Oil pressure sensor has been changed twice with genuine. Oil filter changed twice. Filter housing claimed nothing damaged nor missing, haven't seen it myself.

Fault code: P0521 00 engine oil pressure sensor performance current

Cold oil, idle speed, pressure variation from 0.4 to 0.88 bar.

White Light Product Rectangle Azure


Raised engine speed, oil pressure falls on its face as in the picture:




Photograph White Light Rectangle Product


Found that the oil pressure at idle should be above 1 bar.

We took a measurement on another similar car, 2017 and saw this, which seems normal, pressure at idle was about 1.1-1.2 bar hot.

Photograph White Light Rectangle Slope


Oil control valve has been changed, I was against it, of course it did not fix it.
On the good car we noticed the following: when valve is active, pressure drops, so seems to be like a bypass valve.

Does anyone know the oil circuit of this engine and what can cause so low oil pressure and behavior? Engine does not knock.

  • oil pump suction blocked?
  • oil pump air suction but from where?
  • bad oil pump?
  • anything else?
 

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On other engines a poorly made oil filter element has been known to have the same effect.
 

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I'm not familiar with the inside of the filter housing on this engine but i would assume its the same as most other GM engines, the easiest way to explain the common fault is to watch this video, then check the inside of the filter housing,.. its also possible as @Koicarpkeeper states above, that a poorly made filter will also prevent the valve from seating causing low oil pressure,....

 

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Tigra Twintop 1.8 AT Z18XE AF17
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Discussion Starter · #4 ·
Video was seen but the housing is not the same at the bottom cap. It has been checked 3 times and also 3 filters have been changed. While nothing can be excluded, it appears a fault in this area is less likely.

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@TTT What was the "distribution chain" you replaced ?
Do you have the diagnostic for the P0521and P06D-a-b-c-d pressure codes ?
i could pm you them and some specs if you don't have them.
Those engines do suffer with timing chain issues due to a bad design oil fed tensioner,it probably won't be anything to do with your issue and you probably already know this but the tensioners have been modified and they now fit a gasket under the tensioner to reduce oil drain back
 
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Tigra Twintop 1.8 AT Z18XE AF17
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Discussion Starter · #7 ·
Oil pressure has been measured at the dealer, tbh I don't know what they found nor I've been told.
@Valer, I'm helping with the diagnostic on the electrical and control side, distribution chain has not been replaced, but I've seen a video where this was slapping too much to my opinion. I don't have access to diagnostic steps on the fault codes, however, it can't be on the wiring on sensor side. My line of thought is that with a defect sensor, you would expect maybe a linear difference of measured pressure to the real pressure, which is not the case here. Once the oil pressure control valve opens, the pressure actually drops instead of increasing. And does the same with 2-3 oem sensors. If there was an wiring fault, this would behave more erratic, especially with the vibrations of the engine. I believe the measured pressure to be accurate.
I wonder if missing a gasket would be the cause to loose about 0.7 bar?
 

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I doubt it's the gasket as the vast majority running around won't have had one fitted and the issue you have isn't coming up as a common one,the solenoid is working the right way,my offer stands if you do find you want any pdf's


"System Description
The engine oil pressure control solenoid valve is used to control engine oil pressure inside the mechanical engine oil pump. The control module controls the commanded state of the solenoid valve based on the following inputs:
• Engine Speed
• Calculated Engine Oil Temperature
• Engine Oil Pressure
• Engine Run Time
When the solenoid valve is commanded Off, oil pressure is higher.

When the solenoid valve is commanded On, oil pressure is lower."
 

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Tigra Twintop 1.8 AT Z18XE AF17
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Discussion Starter · #9 ·
Thanks all, been informed it's fixed. Oil pump replaced and no more warning messages nor fault codes. That's all I know.
 

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Thanks all, been informed it's fixed. Oil pump replaced and no more warning messages nor fault codes. That's all I know.
70.000 miles, helping a friend.

Story is after oil and oil filter change (take a bit grain of salt), this error pops up in the dash after 3500 rpm. Distribution chain found loose, replaced. Oil pressure sensor has been changed twice with genuine. Oil filter changed twice. Filter housing claimed nothing damaged nor missing, haven't seen it myself.

Fault code: P0521 00 engine oil pressure sensor performance current

Cold oil, idle speed, pressure variation from 0.4 to 0.88 bar.

View attachment 100930

Raised engine speed, oil pressure falls on its face as in the picture:




View attachment 100931

Found that the oil pressure at idle should be above 1 bar.

We took a measurement on another similar car, 2017 and saw this, which seems normal, pressure at idle was about 1.1-1.2 bar hot.

View attachment 100932

Oil control valve has been changed, I was against it, of course it did not fix it.
On the good car we noticed the following: when valve is active, pressure drops, so seems to be like a bypass valve.

Does anyone know the oil circuit of this engine and what can cause so low oil pressure and behavior? Engine does not knock.

  • oil pump suction blocked?
  • oil pump air suction but from where?
  • bad oil pump?
  • anything else?
Make sure the plastic oil filter cover is fully screwed home. I had this on a Suzuki Splash (same as Agila) and after an oil change the low pressure light was on below 1500 rpm. Gave the filter cover half a turn and the light went out. Being plastic, I was over-cautious to not tighten too much.
 

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Tigra Twintop 1.8 AT Z18XE AF17
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Discussion Starter · #11 ·
Had the chance today to see the car and the old oil pump. These cars are designed with failure in mind, they use plastic pieces inside the oil pump, tomorrow I show you picture how this pump fails.
 

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Tigra Twintop 1.8 AT Z18XE AF17
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Discussion Starter · #12 · (Edited)
I haven't realized at the time that my photo was out of focus, I am sorry for it, but details can be seen.

We opened the old pump and we kind of knew that we don't deal with a total failure of the pump, there were no metal particles to be seen in the oil or oil filter. Few bolts out and pump was opened in two. It didn't took long to spot something unusual. What looks like an plastic piece, it's not really plastic but something harder, was sitting in an oil channel, partly blocking it. about 2-3 cm long. There was another one sitting in a flushed area, but hold in place by a tiny metal bar. Awkward to me, seems that all the assembly with the shaft can move clockwise and anticlockwise against a big spring. Thus opening a gap for that plastic piece to move forward into the channel. And its not that the channel is blocked seems to be the main issue, but it kind of partly blocks two passages, which could be something to do with control pressure areas?

I have no understanding how this pump works, but why on earth use these kind of materials in a oil pump? New pump is 700 euro. We took a graph of the oil pressure and to our surprise, we learned that our previous measurements on a "good car" actually shows similar patterns of failure. That car will fail in the same way very soon. I will post a comparison photo asap.
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Automotive tire Motor vehicle Bicycle part Gear Vehicle brake
 

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Tigra Twintop 1.8 AT Z18XE AF17
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Discussion Starter · #13 ·
Herewith a comparison between what we thought was a good car (now not so good anymore) and after oil pump replacement. Pretty obvious that the oil pressure control should be smooth. Look at the new pump how fast it raises the oil pressure at lower rpm than the other car.

Not so good car but still no fault codes:

Photograph White Light Rectangle Slope


After oil pump replacement, look how less ripple noise the signal has:

White Rectangle Light Product Black
 
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