Limp mode - Over boost?

[dangerdan]

So Ive got an issue with my Ibiza Cupra TDI, the other day whilst pulling uphill and onto a motorway (so pulling some) the car went into limp mode. I turned off the car and turned it on again as its done this before and usually its fine again for a while. Anyway this time round it did it again, and this time the engine management light came on. I turned the car on and off again and the car returned to normal but the light remained on my dash.

The next morning the light wasn't there and so I assumed all was ok. Today I took the car and and was giving it some stick, and at 3500 rmp it did the same again and the light has returned.

So two questions, has anyone in the Maidstone area got VCDS and is proficient with it willing to come and have a look at it for me?
And secondly anyone experienced this before, do you have any idea what it may be? My only thoughts atm are its overboosting or not getting enough air flow!?

 

[lil3520]

mine went into limp mode once. my problem was the turbo pipe had come off !!!!!!!!!!!!

 

[dangerdan]

It cant be that as restarting the car makes it reset and run fine until the issue reappears.

Ive plugged into VCDS and got the error code 17965 - Over boost!

So correct me if Im wrong but that's either the vacume pipe, stuck actuators or faulty sensor!?

 

[dangerdan]

So to add to this I've just been out and driven it hard, up to 5000rpm. Logging the turbo requested and received pressures... and not a problem. Drove like a beaut - so I'm thinking its now the sensor as the fault appears to be intermittent. Am I on the right lines?

 

[dazzerd]

So to add to this I've just been out and driven it hard, up to 5000rpm. Logging the turbo requested and received pressures... and not a problem. Drove like a beaut - so I'm thinking its now the sensor as the fault appears to be intermittent. Am I on the right lines?

id of said sticking vanes in the turbo

 

[DavieTDI]

id of said sticking vanes in the turbo

+1
Had same issues and stuck some innotec turbo cleaner on the veins and let that sit for an hour while working the VNT rod every so often. is an easy fix

 

[dangerdan]

Ok, Ill have a look guys, thanks

 

[Dan FR]

VNT is most likely, 95% of TDi's I look at for overboost are caused by the VNT mechanism

They are not always seized and not always problematic, it can be intermittent, so one good log does not prove the mechanism is ok and free.

Drive it gently until warm, then log it the first time you boot it, it'll probably be seized and overboost massively, then it'll free up a bit and seem fine

 

[dangerdan]

Ok thanks, so it'll still need clearing then from what your saying?

 

[Dan FR]

Without seeing the car and logging it, it's impossible to say 100% what the cause is, but most are clogged and partially seized nowadays given they are all 10+ year old and covered 100k plus miles

 

[dangerdan]

Ok thanks. Would you recommend using one of those turbo cleaner adatives (Im not convinced) or I am better off just taking it apart and cleaning it fully myself? (I did that with a Passat!)

 

[Dan FR]

Cleaning it with something you add to the turbo through the manifold/downpipe (such as innotec or the fabled 'Mr Muscle' treatment) will help, but it will only partially clean the ring gear. Not a patch on a full strip down and clean.

Verify that it is the vanes (you can run a VCDS output test to cycle the actuator, or get under the car and move it manually), and if it needs it and you have the means to strip it and clean it, i would definitely recommend it

 

[dangerdan]

Ok thanks for your help.