Turbo issues?

[mattievrs]

Ive just got myself a vRS and have a question! The car goes fine but occasionally the turbo doesnt seem to work! If the engine is switched off and restarted it is fine again but it just lacks any punch from the turbo occasionally in all gears as though the turbo isnt working.Any ideas?

Thanks

[Wardy]

Is it below a certain amount of revs?

[mattievrs]

No mate it just seems to have no boost in any gear at any revs until the engine is turned off and then restarted.

[Jabbasport]

Sounds like an over or underboost issue, the ecu will then revert the VNT to wide open which creates very little boost.

Kev

[mattievrs]

How would i solve this issue? Sorry it's my first turbo car!

[Wardy]

My first step would be a diagnostic check with VCDS (VAG-COM) to determine whether any faults have been recorded relating to this issue. This will then hopefully narrow down to list of possible causes (and solutions).

So a good independant garage or helpful local member with the right equipment would be my next port of call

Steve

[mattievrs]

right guys its been to the garage today and they used vagcom on it and it has no stored faults at all! :(

ve had a look around the engine bay and the only thing im not sure about is i can hear a quiet hissing from around the turbo piping area somewhere(obviously with the engine running!)Is this normal?

Also is there a way of cleaning the induction and turbo using some kind of carb cleaner?

[K4HN]

hi sounds like a boost leek, check all the pipes from the intercooler to the turbo and also check the small ribber pipes, theres also a metal pipe behind the egr that can often leek but the hissing is normally loud

[devonutopia]

Hi Matt - I am up your way visiting relations on weekend of 1st May so would be happy to take a look. It does sound like a boost leak to me, and for this reason I am gobsmacked there are no fault codes stored. Usually with a boost leak, you losing boost through a weepy connection means the boost sensor does not see the requested boost and the limp mode you are dropping in to usually brings up a fault in the engine section along the lines of "Thrust sensor: Negative deviation" as in the boost seen is deviating negatively from what it is requesting.

I have vagcom and know the typical classic areas boost leaks occur, so if you can wait 2 weeks, I will be glad to take a look. I will be staying either in Kibworth or near Houghton on the Hill.

[mattievrs]

Hi Matt - I am up your way visiting relations on weekend of 1st May so would be happy to take a look. It does sound like a boost leak to me, and for this reason I am gobsmacked there are no fault codes stored. Usually with a boost leak, you losing boost through a weepy connection means the boost sensor does not see the requested boost and the limp mode you are dropping in to usually brings up a fault in the engine section along the lines of "Thrust sensor: Negative deviation" as in the boost seen is deviating negatively from what it is requesting.

I have vagcom and know the typical classic areas boost leaks occur, so if you can wait 2 weeks, I will be glad to take a look. I will be staying either in Kibworth or near Houghton on the Hill.

Hey cheers for the reply! Im sure its a boost leak now as the turbo seem to do a lot of whistling as soon as the throttle is used whether its booting it or gently resting my foot on it and teasing the revs! Im going to have a look on sunday but if i dont get anywhere then i will 100% take you up on the offer of meeting you so you can have a look for me.There will be some beer tokens in it for you! Ill keep you informed and pm you if i dont get anywhere!

[Jabbasport]

Either that, or as a second option pop it over our way and i'll take a look for you..

Pop in if you're this way Jason

Kev

[devonutopia]

Either that, or as a second option pop it over our way and i'll take a look for you..

Pop in if you're this way Jason

Kev

Not sure I am going that far east, and you lot won't be open for the May Day bank holiday weekend will you? I am at Mallory Park on the saturday anyway.

[mattievrs]

Not sure I am going that far east, and you lot won't be open for the May Day bank holiday weekend will you? I am at Mallory Park on the saturday anyway.

hmmmm i live about 15 mins from mallory! I might come down either way!

[devonutopia]

Its PPC (practical performance car) In The Park on the saturday.

[jacko2111]

Just wondering, did you ever sort this out, as I am experiencing something similiar with mine (05 plate VRs). Lost all boost on the way home last night, couldn't even hear the turbo. Then later getting 'some' boost with an extra whistle as though it's leaking boost somewhere!! Are the wastegates known to stick on these???

Cheers all

Rich

[Gouldy]

I know exactly what it is and it wont show up on any VAG com or diagnostics machine either.

Its your MAF sensor, change it and you will be amazed. £57 exchange on a bosch item from GSF or euro car parts. its nothing to do with your turbo matey

[jacko2111]

I know exactly what it is and it wont show up on any VAG com or diagnostics machine either.

Its your MAF sensor, change it and you will be amazed. £57 exchange on a bosch item from GSF or euro car parts. its nothing to do with your turbo matey

Brilliant, any idea what the extra whistle I can hear is though? It just doesn't sound like the usual turbo whistle, hence the reason I assumed it might be a leaky boost pipe somewhere!

Cheers

[jacko2111]

Just tried running it without the MAf sensor plugged in, and it ran even worse! Is it still likely to be this, or would it run the same if the MAF sensor was buggered??

Cheers

ps, Also, mean't to say, it now comes on boost at about 2500rpm instead of earlier, and if you try to hold the revs at a constant 2500rpm in neutral, they fluctuate a bit!!

Edited 18 May, 2010 by jacko2111

[allytech]

Sounds more like a sticking vnt issue than anything else

[Gouldy]

does it make a whooshing noise under acceleration?

if so could be a boost leak. also try checking all you hoses for damage and incase one had popped off somewhere

[jacko2111]

Yep, makes a whooshing noise as opposed to the usual turbo whistle, and seems to come on boost later(about 2500rpm) and not as impressively!!! Have got the front end off and check all the pipes to and from the intercooler, haven't managed to get to the one from the turbo yet!!! Have put a pipe on the diaphram thingt that activates the VNT and I can feel it move, doesn't seem to move alot though, perhaps 1cm! Had to tell from feel alone!

Also, if it is the VNT, what's the answer, new turbo, or can I take it off and clean it? Sorry to sound thick, all this turbo malarky is new to me! :(

Edited 18 May, 2010 by jacko2111

[mattievrs]

mines sorted now mate.Ive had the fault codes read then cleared and have replaced all the boost seals and put a carton of diesel cleaner in a full tank and it hasnt gone into limp since.3 weeks now and counting.

[sniper29a]

HI guys,

I have got exactly same problem now. My first turbo car. I used to have Subaru Impreza non-turbo ) I have got recently Fabia 1.9TDi 2001 (6Y). There was broken airbox so I have replaced box. Unfortunatelly, it is different airbox (bought from scrapyard) so I have got possibly airbox from VRS (biger inlet pipe). I have machined an adapter to fit original and used both MAF sensors. VRS MAF sensor is rubbish and original as well ) I wonder whether is both sensors faulty. My car run well for 1000miles. Then I changed airbox and MAF. Car became very lazy. I have checked all pipes leading into turbo and intercooler. All is ok. Vacuum pipes are ok now as well. Pneumatic valve works too. Even tried to open airbox and emulate initial cracked airbox ) Result same, lazy car.

No fault reported by VCDS. Everything seems ok except car is running not very well.

I have done boost presure test via VCDS. I have found out that boost presure with pneumatic valve on is too high. Since I did not find repair manual for Fabia. I assume that OCtavia 74kW 1.9TDI engine is same or similar. There suppose to be boost pressure 80-250mbar. I have 1030mbar. Shaft on turbo is moving. Test drive, 3rd gear and max load is ok. There is correct boost in range of 1850-2200mbar. It is just lazy from very beginning so there is something wrong I suppose.

BTW that whoosh noise is alternator belt ) I was wondering about that as well. I thought it is some air leak. This noise comes from left-front-top side of car. If you check that noise from the bottom of car, nothing. If you check from the left back side, nothing. I have dismantled almost half of engine bay ) No pipe leak, either intercooler pipes/hoses nor vacuum pipe leading to vacuum reservoar (rubber pipe comes underneath of plastic intercooler hose).

My question is:

is it caused by modified airbox? ( I assume that ECU is able to cope with higher airflow throught the inlet manifold. Theoretically it may be even better with modified inlet manifold. Once I finish this bloody boost problem. There will be a project of conical filter with adapter for MAF sensor and exhaust gases back-pipe ) Does anyone tried this already? I haven't find anything like that. Everybody just put in Seat PD160 inlet pipe

should it be MAF sensor as someone has already written?

is it faulty turbo? (tried to move the boost control shaft by hand. it is quite hard. you have to push it really hard against some spring or so. I am not sure how hard suppose shaft to move. Since there is not big vacuum pressure. I guess it has to move really easy.)

any help appreciated.

for guys with similar problems. I can provide step-by-step guide for testing boost pressure in case you don't have such a info and got VAG-COM/VCDS

Regards

sniper29a

Edited 18 May, 2010 by sniper29a

[sniper29a]

mines sorted now mate.Ive had the fault codes read then cleared and have replaced all the boost seals and put a carton of diesel cleaner in a full tank and it hasnt gone into limp since.3 weeks now and counting.

what diesel cleaner did you use, please?

[jacko2111]

mines sorted now mate.Ive had the fault codes read then cleared and have replaced all the boost seals and put a carton of diesel cleaner in a full tank and it hasnt gone into limp since.3 weeks now and counting.

Cheers, will try to get to GSF at dinner and see if I can get some seals and get them changed, couldn't feel any leaks though yesterday, although I haven't yet got right underneath it to the pipe from the Turbo to the intercooler!

thanks for the update though.

Rich