A2 Tdi Maf Sensor Problems ?

ecoangel said:
Gaff have you checked the air filter?

Mine's now K&N unit - recylcable as well.

Any leaks in the air intake system?

Also have you checked the VTG turbo for stickiness? The vanes get clogged up with soot (like chimneys) if car used on short runs or in eco mode all the time without full throttle useage.

You might have to remove the unit and either get it proffessionally cleaned or buy an exchange unit. Mine clogged up after 85000 miles.
Click to expand...

Air filter is new. Cannot see any leaks, but I am certainly going to check the piping and all of the vacuum lines again.

Last night I found an excellent webaddress with tips on checking EGR valve, N75 pressure control valve, MAP sensor. All todo next weekend.
http://www.tyresmoke.net/ubbthreads/showflat.php/Cat/0/Number/281608/page/0/fpart/1/vc/1
(corrected!)

cheers

GA
 
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ecoangel said:
..//..
Also have you checked the VTG turbo for stickiness? The vanes get clogged up with soot (like chimneys) if car used on short runs or in eco mode all the time without full throttle useage.
Click to expand...

I can drive all day without going above 3000 rpm. In eco mode the motor is ticking over for perhaps 20% of its use. The soot problem is quite a restriction on the eco use of the car?!!

GA
 
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Gaff said:
Air filter is new. Cannot see any leaks, but I am certainly going to check the piping and all of the vacuum lines again.

Last night I found an excellent webaddress with tips on checking EGR valve, N75 pressure control valve, MAP sensor. All todo next weekend.
http://www.tyresmoke.net/ubbthreads/showflat.php/Cat/0/Number/281608/page/0/fpart/1/vc/1
(corrected!)

cheers

GA
Click to expand...

I've had a look at that web page. I'll be interested to see what you find and if you can identify where the relevant parts are N75 valve, VNT mechanism and EGR valve I and others will appreciate it - or even better a photo or 2.
 
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Have you checked the pipes behind the turbo. These are prone to pop out of place. I had similar troubles with mine and fixed it by poping the tubes back in place. :)
 
Foghorn said:
I've had a look at that web page. I'll be interested to see what you find and if you can identify where the relevant parts are N75 valve, VNT mechanism and EGR valve I and others will appreciate it - or even better a photo or 2.
Click to expand...

I can identify the N75 and EGR. See attachment. VNT Mechanism is down the back of the engine, a rod that goes into the turbo.
Happy to update the photo or make a complete labelled engine bay with help!

GA


P.S. Updated the image. The N75 valve was wrongly labelled.
 
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spike said:
Hi Foghorn
Gaff's car is a 1.2 LHD so the pic (very nicely done by the way) is not completely representative of a 1.4 tdi engine bay. Also, variable geometry turbos are only fitted on the 1.2 and 1.4 90bhp engines.
For anyone with a 1.2 or 90tdi who missed the previous link on stripping/cleaning VG turbos (provided by Ecoangel I think), here it is again
http://www.technologie-entwicklung.de/Gasturbines/VNT15-Turbo/vnt15-turbo.html

Cheers Spike
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Thanks for that - I thought the engine looked different - but I have not taken the insulating cover off yet!
 
Found the problem

A pipe running from the charge pressure control valve n75 to the charge pressure control unit (waste gate actuator) had seperated.
Why did it take so long to find ?
The pipe runs off the valve (n75)in green braided pipe but swops over to plastic, the swop is done above the air intake scoop so its impossible to see unless the pipe is dangling, unfortunatly for me the pipe had separeted and was being held there by the insulation around the air intake. Its a bit trickey to take the air intake off but you will need a T20 bit for two screws holding the front of the intake, 10mm long reach socket and extension for 3 bolts holding the back of the intake 2 bolts holding 3 valve assembley the furthest right being n75,17mm spanner to remove wiper so the trim panel under the wiper can be removed so you can get at the T20's however with some pushing it is possible to get at them without removing the trim but you do risk damaging the trim if your not gentle. Once removed you will see the connections .:)
 
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megapup0 said:
A pipe running from the charge pressure control valve n75 to the charge pressure control unit (waste gate actuator) had seperated.
Why did it take so long to find ?
The pipe runs off the valve (n75)in green braided pipe but swops over to plastic, the swop is done above the air intake scoop so its impossible to see unless the pipe is dangling, unfortunatly for me the pipe had separeted and was being held there by the insulation around the air intake. Its a bit trickey to take the air intake off but you will need a T20 bit for two screws holding the front of the intake, 10mm long reach socket and extension for 3 bolts holding the back of the intake 2 bolts holding 3 valve assembley the furthest right being n75,17mm spanner to remove wiper so the trim panel under the wiper can be removed so you can get at the T20's however with some pushing it is possible to get at them without removing the trim but you do risk damaging the trim if your not gentle. Once removed you will see the connections .:)
Click to expand...

Congratulations on finding the problem!

On the LHD version the same tube is easier to follow, it runs almost straight down from the N75 valve to the turbo. I'll check mine a second time just in case!
GA
 
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