Hi All..

Can anyone shed some light..I have a standard mk1 vrs with 88k, it's not a bad runner etc.. The only issue I have had is a little high oil usage, maybe 1\4 litre a month. I cleaned the TB the other week and found quite a lot of clean oil in there so assume my turbo seals may be a little tired. Anyway, that aside, I just took it to Cornwall for the week which is a trip of 350 miles plus driving around all week, all in all 1000+ miles in 6 days.

Now I noticed a funny issue while out and about, in the morning, car runs perfect, just as it should, turbo boosts up from just before 2000rpm and plenty of power, get to where ever I am going and park up for 2 or 3 hours and then return to the car around lunch, start up, car runs fine but then..no turbo! I can drive the car fine but its well down on power and if I open the window I can't hear the usual turbo whistle or the recirculation valve between gears, there is also the smallest of stutters when changing gear..barely noticable, Switching off and on makes no difference. But then when I park it up and return later again in the evening all is well again?? I only have a basic fault code reader which is clear, the car has only just been serviced by a main dealer and diognostics were clear then too. I drove the car back last night and it performed flawlessly for the whole journey. I know it sounds odd, but I think it may have done this previously on my commute home from work, but as I am usually stuck in traffic it is difficult to tell, it seems to me that when the ambient temperature is high the turbo plays up, then when the day is cooler all is well, is that even possible?

Has anyone else has a similar issue or any advice on things to poke at under the bonnet?

Cheers...

hi m8

strangely mine did the same last nite,but i got no turbo at all,it struggled to get to 70mph lol

ill keep an eye on this thread to see if anyone can shed some light on it

For diesels, causes of this could be a failing MAF or n75 valve. Not sure if this is applicable to the 1.8T though.

Edited 26 June, 201016 yr by mbames

Sounds like you might have fault code 17705 ?????

fault cade 17705 can cause the car to go into limp mode but not put the engine warning light on.

Next time it does it..... try stopping and restarting the engine which should clear the fault code.

Bill.

17705, that thought crossed my mind, I have recently been under the car to fix the secondary air pump issue, while I was there I checked as much as I could, including the pancake connections, I'm reasonably certain I don't have a boost leak, and the absence of fault codes and a clean engine bay etc..Tried the on and off and didn't fix, though it corrects if left for a few hours untill cooler weather it seems. I dont get the engine light on either.

NB, I have been in and out of the car today quite alot and have had no problems, so it is intermitent which could point to something electrical breaking down..Any way of checking the MAF or N75 for certain?

To check the MAF run with it unplugged and if it runs better with the MAF unplugged (it will use preset values) then your MAF is goosed.

N75 no easy way to check best to borrow a known working one and try it

Sounds like you may have a boost leak which is only happening when things are getting hot, perhaps a pipe or hose is expanding and something is becoming loose. I'm suprised you don't get a code and an EML if it's going into limp mode though.

im having a similer thing and a really uneven tickover,somtimes stalling when slowing down so i scanned it,it came up 17705 so i checked around and found a split pipe which i fixed,still has a bad tickover so unplugged the maf which made it tickover fine so im taking it that it needs a maf.also came up with 17535 too rich on bank 1 so im guessing there both caused by faulty maf

im a bit new to all this lot so sorry for questioning it again

Im having same probs. Car will run fine but suddenly lose all boost pressure for a while then it will come back. Ive recently had a remap and was wondering if it has affected something. Looks like it might be the n75 valve or possibly the MAF judging by other peoples suggestions. I was wondering if my DV was a prob as its the only thing i have been messing with. I had put an atmospheric DV on before the remap and was told to put the original back on. Made one hell of a difference when I did! for about a day when the ignition coils failed. Replaced all those and had this boost prob ever since. All pipes are tight to the DV, im thinkin of replacing it with a uprated recirc DV to make sure it isnt faulty. I sometimes feel like the boost is fluctuating, will pull like a train then a few mins later wont feel as quick.

Dont think it goes into a limp home mode, as it pulls ok with no boost, just feels like a normal aspirated car, im thinking its restricting the boost or venting some of it

Edited 6 July, 201015 yr by jomibo

jomibo,

That does sound like limp mode, what it will do is restrict the boost pressure to something like 5 psi so it practically feels like you have no turbo.

When you got the remap did they give you a boost plot or even just a figure of what peak boost it's making? If it is a very high figure then firstly your DV might not have a strong enough spring to hold the boost pressure while it's boosting and secondly it will be putting more stress on hoses, valves etc.

Before you go buying a new N75 and MAF there are cheaper ways to check if they are really the problem. You can swap the N75 for a known working one from anyone near you with a 1.8T car of a similar age, just long enough for you to give it a drive and see if that cures it. Likewise with the MAF you can just unplug it and if the car runs better with the MAF unplugged then the MAF is the problem.

Edited 7 July, 201015 yr by chicken_eyebrow

When I had the remap it didnt do anything because I was running an aftermarket atmospheric DV, only noticed the difference when I put the original back on then it went like a bat outta hell.

Would a standard N75 valve be ok or would I need a better one?

My TDi does the same thing every now and again, so did my wife's L&K TDi, so did the TDi she had before that.

Skoda dealer say the same thing every time... sticky turbo.

Hi all, Thanks for all the responses, thought I'd update..I didn't find any fault codes, the car has not repeated the issue since those exeptionally hot days while on holiday, although from the descriptions I'd say it was in limp mode briefly for whatever reason.. Anyway..One good thing has come out of taking the car on such a long run. I had posted on here a while back on oil usage, after I brought the car it became apparent that I was burning oil, although my dealer said it was in acceptable limits it was using about 1 litre a month! Well not anymore...not a drop since I got back, I had a really clear run out of Cornwall, motorway speeds for pretty much the whole journey for 5 hours, Its must have cleared all the breathers and such like..That is a massive difference by any ones measure, I thought the turbo seals or valve stems, as thats what most of the advice points to, who'd have thought!..