Vacuum pipe fixes, also "NEW Question" Can you damage MAP by cleaning the sensor itself?

[Sylvester]

Hi all, I've been having this issue for a month, code reader showed:

17950/P1542/005442 - Angle Sensor 1 for Throttle Actuator (G187): Implausible Signal

For 2-3 weeks that code went away, and it's been replaced with: 17566/P1158 - Manifold Pressure Sensor (G71): Implausible Signal, sproadic.

I've done my research, (https://www.a2oc.net/community/inde...ix-manifold-pressure-sensor-fault.7756/page-2) and found few older posts saying, that usually it's not the sensor, but crack/hole on the vacuum pipe, due rubbing on other parts.
I've looked around the G71 sensor and found a tiny crack caused my 2nd dipstick. Fixed that. Few days later EML and same 17566 code came back. Yesterday back from work, EPC, EML came on, which normal after some drive, but suddenly all the other start up lights came up as well, with the huge red (!) on the dashboard display. Car started okay today and after 15m drive, "only" EPC and EML came on.
Today I've removed a few bits, so I can get to the breather pipe for better look.
With some effort, eventually both end of the top-hose came off. See pics. Found a few surface cracks, nothing major but I'll tape them up, AND to my surprise the hose inside is covered in some goo. Bottom parts feels the same and around the sensor inn the middle too, I cleaned as much as I could reaching down with cotton buds. It should be all dry, I assume.
I'm gonna clean the top-pipe throughout.

Questions: 1-How does the bottom of the full pipe connects, so I can check that too? Red arrow on pic. Feels like a plastic ring on bottom around it, not a "push & pull" like the top-part.
2-What can cause the breather pipe to be full of wet dirt?

Any other useful info would be appreciated, thanks.

 

[Robin_Cox]

Is that coming from the oil separator down the back of the engine? I had to replace that on our AUA - a lot of oil was going into the TB through that route.

The rubber tube that plugs onto the back of the air intake pipe above the throttle body goes down the back of the engine and corresponds to pipe 35 / 36 on this diagram (the A2 version is a different shape to that depicted, and I hope I've not completely confused what you're looking at) connecting onto part 19 (our 52 reg AUA has the square version, not the later rounded version part 19A that I think may be BBY-specific?)

cylinder block with pistons; oil sump Audi A2 (A2) 2003 year Audi EUROPA 103005

cylinder block with pistons<br/>oil sump Audi A2 (A2) 2003 year Audi EUROPA 103005 spare parts

audi.7zap.com

see also -

AUA Oil Separator - clean or just refit?

In the course of trying to get to the bottom of my Long Term Fuel Trim Additive Air System too Lean error I have just removed the oil separator and attached hose that's behind the engine for inspection. Although the hose shows signs of rubbing in two places, it and the oil separator box look...

www.a2oc.net

The other thing is that the error message about implausible manifold pressure sensor, sporadic - signal can also be related to the oil filler cap not sealing completely on top of the crankcase. Is there any oily residue around the filler cap? Replacement with a new part with better seals is not expensive.

 

[Sylvester]

The other thing is that the error message about implausible manifold pressure sensor, sporadic - signal can also be related to the oil filler cap not sealing completely on top of the crankcase. Is there any oily residue around the filler cap? Replacement with a new part with better seals is not expensive.

Hi Robin, yes the oil cap seals good, no residue, but I'm gonna look for a new one, might as well.
I was thinking about the oil separator too, perhaps the oily wet goo is the reason, the breather hose can't generate enough vacuum and that triggers EML lights?
Probably the G71 sensor dirty as well, so I'll give that a good clean.
Yes that's it, on the diagrams I've cleaned up 35.hose and 37.heater pipe, but couldn't remove 36.hose to the oil separator. Looks like, I need to ramp the car to get access to it.
There was no hose-clip around 35. thought, just pull-and-plug.
Thanks a lot.

 

[Robin_Cox]

Hi Robin, yes the oil cap seals good, no residue, but I'm gonna look for a new one, might as well.
I was thinking about the oil separator too, perhaps the oily wet goo is the reason, the breather hose can't generate enough vacuum and that triggers EML lights?

I don't know exactly how it all works, but I do know that our original throttle body was chock full of tar and the EGR valve itself had failed completely, and the big plastic pipe going into the top of the TB was awash with oil, much of which seemed to be coming from rubber pipe up from the oil separator. Replaced TB & EGR with new ones 3 years ago to resolve the shaky idle and error messages, followed by plugs, leads, injectors and coil the following summer. I seem to remember someone commenting that the OS can almost be considered a wear part as if it isn't in good nick it can cause all manner of issues but is easy and relatively cheap to replace from underneath. The car used to emit a puff of blue smoke on startup up until this time last year every few starts; since the separator was replaced at the time of last year's MOT it has never done so since and our emissions were squeaky clean on all counts, and once warmed up the idle is like a sewing machine.

 

[Sylvester]

The car used to emit a puff of blue smoke on startup...

My A2 got the same! I have around 20seconds bluish smoke too, only at start up, nothing visible afte that. I thought one of the piston seal was leaking oil, as that's expensive job, I didn't bother at the moment. I cleaned the TB 2 years ago and changed EGR too. So now I'm gonna get a new oil separator and get the job done, hopefully that will sort it. Thanks Robin.

 

[Sylvester]

So I've changed the oil separator, looked disgusting and just like the MAP sensor (pictures and details here at Monday 7pm. https://www.a2oc.net/community/index.php?threads/today-i.28729/page-517 ) and patched up all the hoses I could just saw.

Also: is that normal, that black box got like an inch dent on top? SEE PIC

Thanks

EDIT: yes all 1.4 petrol has got dent on the top airbox.

 

[Sylvester]

Hi guys, I've watched a few videos, a bit late, on how to clean MAP sensor, and all say only touch with soft rug on the OUTSIDE of the sensor but NOT the sensor itself.

I didn't know that before, so I'd cleaned the INSIDE too, wires and top ball too properly, with dry cotton pads. Does it mean I broke the MAP sensor (like won't be accurate anymore) OR spraying it with "electric contact cleaner" might help fixing it? Thanks