17705 - Pressure Drop between Turbo and Throttle Valve

[karlbar2k]

If I had any cash I would be doing FMIC off Ebay

[Hacre]

Apologies for bumping an old thread but this came up on my search and seems relevant.

Difference with mine is the fault light seems to take a while to come back on after being cleared, for example I had it cleared well before Christmas, covered about 70 miles or so no problems. Did a run on the motorway yesterday and it's come on again.

It was tested with a hand held reader at a local garage since I've had nothing but problems with my local Skoda dealership, I forget the code but it said Turbo boost pressure drop, check DV!

Is it still a case of checking hoses/cleaning the throttle body, or should I try and get my hands on vag-com and a cable and do some road tests? Everything I'm reading here suggests the stock DV is a bit crap?

Edited 28 December, 2011 by Hacre

[chicken_eyebrow]

It can be all sorts of things, I'd say if it only comes back after 70 miles then it's probably more likely to be a split in a pipe that is opening only once it's warm (or you are using a certain amount of boost), rather than things like the throttle body or N75/DV which are either faulty or not faulty. If you can, try and make a note of what you were doing when the code came up, had you been accelerating under boost?

I'd look to resolve the 17705 in order of expense so

1. Check all vac hoses and boost hoses (free)

2. Check, clean and realign throttle body (less than a tenner)

3. Check and start replacing valves N249, N75, DV etc. (free if you can borrow some off another member, if not then ££s)

If there's another member near you who doesn't mind their Octy being out of action for an afternoon it would be a half hours job to swap the DV's (or N75) then try it in yours.

[Hacre]

It can be all sorts of things, I'd say if it only comes back after 70 miles then it's probably more likely to be a split in a pipe that is opening only once it's warm (or you are using a certain amount of boost), rather than things like the throttle body or N75/DV which are either faulty or not faulty. If you can, try and make a note of what you were doing when the code came up, had you been accelerating under boost?

I'd look to resolve the 17705 in order of expense so

1. Check all vac hoses and boost hoses (free)

2. Check, clean and realign throttle body (less than a tenner)

3. Check and start replacing valves N249, N75, DV etc. (free if you can borrow some off another member, if not then ££s)

If there's another member near you who doesn't mind their Octy being out of action for an afternoon it would be a half hours job to swap the DV's (or N75) then try it in yours.

Thank you for this.

One question...how do I get to these components to check them? My Haynes manual is bizarrely unhelpful, for the petrol turbo it just tells me how to remove it, but not where it is or where any of the hoses are.

[chicken_eyebrow]

Thank you for this.

One question...how do I get to these components to check them? My Haynes manual is bizarrely unhelpful, for the petrol turbo it just tells me how to remove it, but not where it is or where any of the hoses are.

For the large pressurised turbo hoses follow the pipework from your turbo at the back of the engine, down the side to the intercooler behind the bumper then up to the throttle body, check every one of those hoses is on correctly and not split.

The smaller vac hoses for the turbo control system are mainly either on the airbox side of the engine (lift off the larger engine cover to get to them) or they're underneath the inlet manifold (remove the smaller engine cover and the plate that's screwed to the manifold to get to those)

N249 is under the plate mentioned above

N75 is plugged into the inlet pipework between the MAF and the turbo

DV is also in the inlet pipework before the turbo

The diagrams on RobClubleys site are really useful for figuring out where the pipes and valves are: www.pimpmyskoda.co.uk

[OU51]

There's a lot of useful info here that should help a bit at least... http://www.pimpmyskoda.co.uk/Engine.htm#N249_System_Removal

edit: Opps, a bit slow!

Edited 8 January, 2012 by OU51

[karlbar2k]

One of the things you should really consider is a pressure or smoke test, preferably from someone that know the 1.8T as there are a multitude of places that could leak (boost and/or vacuum). I made my own from a tyre valve and a bean tin I am a bit of a pikey though.