a frustrating dilema............

[VAGMAN1]

following on from my earlier post re. power-loss problems which I thought I had sorted, but are not........

just to recap, on my TDI 110 I'm experiencing random power loss when driving between 60-80mph and between 2500/3000 rpm - you just suddenly feel the turbo die and the car goes in to obvious limp mode but no dash warning lights are triggered. I've had a diagnostic done (not by a VAG dealer) and it showed a code referring to 'turbo overboost' - they said the most likely cause was a sticky boost pressure solenoid valve (otherwise known as an N75). Replaced this and also checked the VNT mechanism on the turbo - you could easily by hand so no problems there. After all this the problem is still there..........

so my options are replace more parts which I think it could be, and it really could be any number of things OR pay £70 for the Audi dealer to run a diagnostic program which cycles the turbo system and should point to the fault.

It's been suggested it could be the EGR solenoid valve which is only £35, but then what if it isn't this either?!

 

[madvw]

sounds to me like taking it to the dealer it could be £70 well spent then.

out of interest, as your in norfolk, have you tried Clive Atthowe in norwich?

I've never tried him personally (did that sound bad?), but others on here have, and he's a bosch specialist....

 

[Ess_Three]

[ QUOTE ]

just to recap, on my TDI 110 I'm experiencing random power loss when driving between 60-80mph and between 2500/3000 rpm - you just suddenly feel the turbo die and the car goes in to obvious limp mode but no dash warning lights are triggered.http://www.audi-sport.net/ubbthreads/addpost.php


[/ QUOTE ]

My old man has exactly the same problem with his 130PD...
Is the 110 a variable turbine vane turbo like the PDs? If so, could be the same problem...if not..lgnore all of the waffle below!!


[ QUOTE ]

I've had a diagnostic done (not by a VAG dealer) and it showed a code referring to 'turbo overboost' - they said the most likely cause was a sticky boost pressure solenoid valve (otherwise known as an N75).


[/ QUOTE ]

Same code on my old man's...
But it's nothing to do with an N75 on his...


[ QUOTE ]

Replaced this and also checked the VNT mechanism on the turbo - you could easily by hand so no problems there. After all this the problem is still there..........


[/ QUOTE ]


Bingo!
That's the issue on his.
You can move the turbine variable vanes by hand when cold...but when hot, they stick, cause overboost and it hits limp mode.


[ QUOTE ]

so my options are replace more parts which I think it could be, and it really could be any number of things OR pay £70 for the Audi dealer to run a diagnostic program which cycles the turbo system and should point to the fault.


[/ QUOTE ]

It's up to you...but according to my VW MasterTech mate, this is a reasonably common problem on these TDIs...and it's almost always the variable vanes on the turbo.

I'd be tempted to point them in that direction...and get them to prove you wrong...or not, as the case is likely to be.


[ QUOTE ]

It's been suggested it could be the EGR solenoid valve which is only £35, but then what if it isn't this either?!

[/ QUOTE ]

Causing overboost?
I can't see it...the turbo is most likely.

 

[VAGMAN1]

interesting post Ess_Three, and I see your logic

it is a variable vane turbo on the 110 TDI engine

in which case I assume the problem is caused by soot build-up and a turbo strip down is what's needed.......?