Hi guys,

I just bought a O1 RS (old Mk2 Golf dead due to frontal impact :().

The car looks ok and even pulls pretty hard, BUT there is a very strange noise coming from the engine compartment. How it sounds:

1. When standing still, in no gear, if I accelerate over 2000-2500rpm it starts to go "woosh-woosh-woosh-woosh". As I release the gas pedal and the rpms go down the wooshing "slows down" then dissapears.

2. In gear, same, when accelerating over 2000-2500rpm it does it again, albeit it seems to me the sound is louder.

As for the intensity of the sound, it's LOUD, I mean in gear I can hear it pretty loud from the engine compartment with all windows closed.

Other notes: I bought the car from a dealer, but he also gave me some receipts from the previous owner. The car *seems* to have a changed turbo, exhaust, intercooler and other parts (can't read German so well) which, from the receipt, cost 5400 EUR and says there "estimated power 240-260 bhp". Could this sound have something to do with this?

Another note is that I have a receipt from about a year ago where it says the car was brought in with "engine noises". Inspection revealed the turbo rotor shaft was broken, so they took it apart. Unfortunately it doesn't say anything about repairing it, just something about "customer brought in the spare parts". The workhourscost for that receipt is 950 EUR, so looks like they at least took it to pieces. Question is: can it still be broken? I mean, the car pulls, I can hear the turbo sound. Is this possible with a broken rotor shaft?

Thanks a lot for any info and excuse my lack of knowledge, pretty big leap from '84 Golf mk2 TD to Octavia rs

With that power, I'll bet there's a modified dump valve in there! In which case what you're hearing is probably perfectly normal!

In fact, even with a standard engine, if you accelerate through that rev range alongside a wall on your right with the driver's door window open and the radio off, you'll probably hear the turbo spooling up anyway, so I'd say that's normal operation.

As for a "still broken turbo", is the car faster than your old Golf? If so, then the turbo's not that broken!

Finally, if you can scan the receipts you need translated, and link them to here from a photohosting account, I'm sure a German speaker will translate then for you.

Thanks for the answer Ken. I'll read up on what the dump valve means... but, from what i know, shouldn't the sound be like one big "woosh"? What i hear are rapid "woosh-woosh-woosh"-es

The turbo seems ok, and it's quite loud, but it makes the specific turbo sound, this one is different.

Anyway, tonight I'll try to get it diagnosed and maybe I'll find out.

Regarding the Golf , yea, it seems to go much faster.

I'll also try to post the receipts later.

Thanks again

If it's a short repeating whoosh sound rather than a constantly increasing one, could it be that it's still on the Bosch DV and the diaphragm is starting to flutter under the increased boost? I've heard a broken one that, rather than making the 'blowing across a bottle top' hoot sounded more like 'pfh-pfh-pfh-pfh' on the overrun.

Ok, I did the Vag-Com testing. No errors across the board, save for one (quoting from memory):

"Boost pressure valve (N249): Mechanical Failure".

It appeared again after being cleared so it's definitely a problem. Could this be the source of my pain?

Interphase: it is a short repeating woosh indeed. By Bosch DV you mean dump valve? Is this the same as the "boost pressure valve"?

Anyway, I'm pretty glad that there were no other errors reported by Vag-Com and I'll start googling right away for the error code found.

Yup on the first part, although my terminology, is dodgy - it's a recirculating valve rather than a dump valve, but the original one on the octy was made by bosch.

From what I understand the N249 boost pressure valve sits between the intake and the dump/recirc valve, and connects one to the other on demand to allow the valve to vent boost at times (other than on the overrun, as usual) when it's not needed. It may be that your N249 is going leaky or oversensitive and consequently, you're losing boost under load during those accelerating moves. The repetitive whooshing might be a consequence of the N249 switching rapidly.

That's as far as my knowledge goes (and I'm fully prepared to be wrong on any aspect of that! )but I gather a lot of people here have had N249 failures causing all sorts of issues. A search should turn up quite a few cases.

Yup on the first part, although my terminology, is dodgy - it's a recirculating valve rather than a dump valve, but the original one on the octy was made by bosch.

From what I understand the N249 boost pressure valve sits between the intake and the dump/recirc valve, and connects one to the other on demand to allow the valve to vent boost at times (other than on the overrun, as usual) when it's not needed. It may be that your N249 is going leaky or oversensitive and consequently, you're losing boost under load during those accelerating moves. The repetitive whooshing might be a consequence of the N249 switching rapidly.

That's as far as my knowledge goes (and I'm fully prepared to be wrong on any aspect of that! )but I gather a lot of people here have had N249 failures causing all sorts of issues. A search should turn up quite a few cases.

:iagree: That would be my understanding too

Tomorrow I'm going to the mechanic for timing belt change, filters, oil and whatever else.

In the meantime, I found a video on youtube with a guy having the EXACT same problem:

Also, I managed today to take the car out for a spin: it doesn't pull AT ALL after 3000 rpm. Up to there it's so and so (i'd say not so good), I can hear the turbo spool up, but at about 3000 the turbo seems to spool down (i can hear it going down) and the power is gone. Could that diverter valve be responsible for this?

Well his problems seems to have been the vaccum tube from the DV dropping off but leaking DV is also mentioned.

This also points to the fault codes your getting.Take the top vaccum hose off (if its on) and try sucking through the top nipple to see if it holds pressure. Also trace hoses back searching for any problems.

I'll do it first thing tomorrow. But question still stands: if the DV is broken (one way or another), is this the reason for the lack of power after 3000rpm?

Also, hope I haven't shortened the life of my turbo significantly by driving some 10km withe this broken DV :(

Also, I managed today to take the car out for a spin: it doesn't pull AT ALL after 3000 rpm. Up to there it's so and so (i'd say not so good), I can hear the turbo spool up, but at about 3000 the turbo seems to spool down (i can hear it going down) and the power is gone. Could that diverter valve be responsible for this?

I had the same problem & never got to the bottom of it, pulls up to 2500-3k then dies & turbo (audibly) spins down, worse under load - also no power persists even at lower revs until you shut off & restart. When it happens & you look at the (clear) fuel hose there seems to be lots of air getting in... Seems to cure with a filter change so my theory is the filter is blocking & collapsing at high flow rates??

DJM, on the face of it, your theory makes sense, but it would need some shenanigans with jacks, stands, tiedowns and a rolling road to test it!

JMF, I doubt you'd damage the turbo, because what seems to be happening is that you're losing boost, which means you're also losing turbo speed.

Back with news: I went and changed the timing belt and whatever related parts today. Also oil (Mobil1 5w-40), oil filter, fuel filter, dust (?) filter.

Regarding the dump valve (which is supposedly called a "recirculation valve"), what the mechanic did was put the pressurized air pistol in it. Then a LOUD "boom!" followed and he said that it was somehow blocked, but now it's working.

Also, by looking around under the bonnet I found out that: the turbo is most definitely changed with a bigger one, together with some metal tubing (instead of the stock rubber one), there is a FMIC which is linked together with the original intercooler and also the exhaust is changed with some wider tubing, up the the final part. Also, there's a K&N sport filter. These I've seen with my own eyes on the car

Looking through some receipts I got from the previous owner I also saw that the cam shaft is changed with a supposedly sport one and also there were some injector modifications.

What I can tell after everything was up and took the car out for a spin:

a) the car now pulls, as opposed to yesterday. It might be because of the now "unblocked" dump valve, I dunno. Compared to a stock octavia 2 rs it feels faster, especially from 4000rpm on. Still, the power delivery isn't that smooth: it's smooth up to 3000rpm, then from 3000 to 4000 it seems to "think about it" a bit, and after 4000 it's brutal

the "psst-psst-psst-psst" rapid succession sound is still there. I had a quick chat with a guy which has a tuning shop and he told me it could be because of the sport air filter, he says his car does the same thing. The sound appears ONLY when lifting the foot off the throttle and is much louder if the acceleration was sudden: if I accelerate gently the sound is still audible, but not so loud. Definitely seems to have something to do with the turbo pressure, but can't say what.

c) the "boost pressure control valve n249: mechanical failure" error is still there. The tuning shop guy told me that n249 is a valve that's "inside" the turbo (?) and I could be getting the error because I've a changed turbo, not the stock one.

d) fuel consumption under "heavy foot" conditions was 18 l/100km avg. After about 25km driven more lightly with alternating short sprints it dropped to 12.8 l/100km.

Conclusion so far: I'm still trying to figure out if that sound is ok. From the comments on the youtube video above it's NOT ok, but this tuning guy says it is. Unfortunately I don't have a DV handy to switch the existing one and see what happens. Is there a surefire way to check the existing DV and know if it's working ok or not?

Thanks!

le: I forgot to say that "foot down" in 2nd or 3rd gear, at about 3000rpm the clutch slips. Any suggestions as to what clutch I'd need to solve this?

Edited 10 December, 200817 yr by jmf

The N249 definitely isn't inside the turbo - I don't think much would survive in there

The difference between a dump valve and a recirc valve is that the dump valve chucks unwanted boost out into the open air (usually with a loud FOOSH) and a recirc valve pours it back into the intake. The Octy has the latter type, and the system will peobably expect it to work that way unless there's been some serious tweaking

Did you manage to check if your valve is the original one, or a replacement fitted to deal with the extra boost that your other mods would suggest? The original Bosch made one probably won't cope with much extra power over stock, and I have heard of them occasionally making the sound you describe when they fail. Can you get someone to rev the engine hard while you have your head over the open bonnet, and then take their foot straight off the throttle? You should hear the recirc valve whooshing the moment they're off the power. If you get the sound you describe from it instead, you might have nailed it.

Dunno about the air filter though - I could understand how a CAI might make the noise from an iffy DV more audible, but not actually create that noise for itself. That would suggest that the air filter was either moving, or somehow impeding the flow of air, wouldn't it?

Mmm bigger turbo :drool:

By the look of it you are getting turbo surge. CAI shouldn't cause this problem, what DV is fitted and if its a Forge what spring is in it?

The recirc valve looks to be a stock one, it's plastic black, not those shiny forge ones. It looks like this one meaning it's the same valve, but it's not chrome, it's black plastic.

I went again for a drive, this time compared to a o2 rs. The difference in power is VERY noticeable in 2nd and 3rd gear, I'd say I have at least 40hp over the stock 200hp of the o2 rs, confirmed also by the o2's driver. The problem is that the power is not delivered smoothly. 2nd and 3rd are still pretty ok, with a small pause betwen 3000 and 4000 then brutal, but 4th gear is basically a series of "power-stall-power-stall-power-stall" from 3000 up to 5500.

The noise, again, is only audible when letting the foot off the throttle. It's audible also when standing still and you can actually hear it from the car with the windows up.

I'll try tomorrow to se if I can borrow a recirc valve from someone (maybe Skoda dealership) and try it on see if it behaves the same. In the meantime I'll drive more slowly to not risk any damage to the turbo because of the valve.

Thanks for the answers and I'll get back with info...

LE: the valve I have now looks exactly like the stock one pictured in the forge dv installation instructions.

Sounds a bit iffy, that - if the previous work went as far as that in search of extra horses, you'd imagine a replacement DV would have been high on the list. Tell you what would be interesting - can you record the sound it's making and host it somewhere? A mobile phone clip with decent sound or an MP3 recording would do.

a series of "power-stall-power-stall-power-stall" from 3000 up to 5500.

if its the standard DV with the extra horses from the other mods it might be getting overwhelmed with the boost pressure. there is a limit to how much boost a standard DV will take (I just dont know what it is:P - pokes out tounge and waits for Lummox to arrive-)

agree with the others though - would have thought a replacement DV would have been high on the shopping list, is there a boost gauge fitted?

No boost gauge there, but I'm thinking about getting one.

The sound it's making is this:

. EXACTLY. Same exact sound.

I'll try to also record mine, but it's 100% same as the above.

Another question: do you have any hints as to what DV I should be looking for that would handle the increased boost?

The forge 007p and a set of extra springs will be just fine.

Did you manage to get a readout from your diagnostic guy about how much boost it was making when things went pear shaped?

I went again for a drive, this time compared to a o2 rs. The difference in power is VERY noticeable in 2nd and 3rd gear, I'd say I have at least 40hp over the stock 200hp of the o2 rs

With a bigger turbo & the other mods you have it should be a lot more than 240 bhp, just a remap on the octy1 will give 225 bhp. My Octy 1 with a Bespoke Exhaust, Jabba custom remap, forge Dv & Front mount gave a consistent 250 bhp

I would suggest you take the car to a reputable vag tuner, stick it on the rolling road & try & get to the bottom of whats going on. It might also be worth having it remapped. At least then you will know what you actually have bought & have a base point to work from.

It would be worth getting the clutch sorted before then. A cheap fix is the Corrado G60 clutch but it all depends what ultimate bhp you are looking at, if the car has a big turbo then this might not be enough, again it would be worth taking the car to a tuner, they can do a visual on what you have bought & say what it ought to be producing, then size the clutch to suit that. If you are tempted to go for a Carbon clutch be warned they are pigs in traffic, I have one on the 350 but had to with 500 ish bhp but in traffic its a real pain, they dont like slipping when warm, its more of an on off switch

Did you manage to get a readout from your diagnostic guy about how much boost it was making when things went pear shaped?

He did a readout while standing still. Except for the "n249: mechanical malfunction" error, everything was fine.

He did no readout on the road and didn't even suggest it. Maybe he didn't know it can be done I'll try going to someone else and doing one.