RS2 Overboost issue - newbie

[Lloyd]

Hi, as Dmitri suggested above, I would focus your energy on doing a complete thorough boost leak test. Don't pressurise over 1 bar. Use lots of very soapy water in a spritz bottle and take your time. Once you have done this and got the results you can look elsewhere (if needed). Good luck

[wowow]

Am I correct in say that the few possibilities that i am getting only 1bar of boost are :
1. Waste gate spring not strong enough ( but it used to be ok )
2. Air leak
3. Turbine problem ( just replace faulty shaft ) if everything else is ok, can a healthy shaft spin but not getting beyond 1bar( maybe faulty bearings ?) this may sound stupid but I am just trying to narrow down the possibility.

[prj]

No, don't touch the wastegate.

Pressurize the intake and fix leaks.

[wowow]

Thanks to many of you and especially URs4Boy's post, I finally get the car running ok. I replaced the N75, all air hose and vacuum tubes...etc. I even installed a modern boost gauge ( waiting for Rusty's RS2 gauge ). Now the car gets power at around 3.5k rpm. but the problem is, the max boost is only 0.9-1.0 bar. I am pretty sure the system is not leaking. Question : should I play around with the wastegate spring tension ? I turn the allen screw a few rounds and it doesn't seem to make any difference. Could the spring be too weak ? I have no idea if it has been changed by the last owner, but if he did, I would have guess he put in something harder to improve power.

[tscheel]

Update from my previous post...

earlier, i said that i remember that my cousin's late RS2 had a digital boost readout, although i was aware that others i had seen did not.

I was both right AND wrong!!!

I called him late last night (oops)! and he did confirm that his car DID have a digiBoost.
However, it was aftermarket.... it was, in fact, the console from a urS4, which i believe fits right in with minor modification!
So no... the consensus is that there were no digi boost readouts, as standard, on the S2, Or RS2.
My sincere apologies to anyone i contradicted or misled!
I already have my coat on.... so shall now exit the building!

Thanks for the tip - I'm considering to make that mod - I'm not in need of the "in your face" meter, but it would be nice to have the option. No need to leave

[LunarWolf]

Update from my previous post...

earlier, i said that i remember that my cousin's late RS2 had a digital boost readout, although i was aware that others i had seen did not.

I was both right AND wrong!!!

I called him late last night (oops)! and he did confirm that his car DID have a digiBoost.
However, it was aftermarket.... it was, in fact, the console from a urS4, which i believe fits right in with minor modification!
So no... the consensus is that there were no digi boost readouts, as standard, on the S2, Or RS2.
My sincere apologies to anyone i contradicted or misled!
I already have my coat on.... so shall now exit the building!

[newsh]

DV is down below the RH side headlight. Very common for it to rub on the chassis leg or towing eye and have a hole in it. I must say your car sounds like it has a leak in one of the hoses. Have a search for boost leak test.

[wowow]

Hi Fat Audi, can you tell me where the "diverter valve"is located, or part number so I can check on the part list. ( Like your "Sirus" avatar )

[Jamo]

I know there is a mod you can do to get the output the ecu does have the pin output for the info I think s2central posted details I'll have to dig

[Fat Audi 80]

I am betting there is a non standard diverter valve on there not working correctly...

[Ross]

I've never seen an RS2 or S2 with digi boost guage, my brother has a very late S2 Coupe and that doesn't have one. Not saying it doesn't and I'm not sure if the posts above are serious or not. You don't have a boost gauge so it's irrelevant anyway.

I'm not sure where you'll find the central vent holder - I have one the same on mine, looks great - but as for the gauge you'll want any mechanical one. For power to the light you'll need to plice it into another power feed - recommend the glove box light - and run a vacuum hose down the vent and out into the footwell by the ECU. Pop the vac line off the ECU, put a T-piece on and then you can connect both ECU and boost gauge to the same feed. That's the way most do it.

Get in touch with 'Rusty' on here, he was supplying a VDO gauge that matches the RS2 stock look:

http://www.s2forum.com/forum/showthread.php?t=41629&page=12&highlight=vdo+boost

It does sound like an air leak to me. The 'spooling sound' is louder (1) because the turbo will be spinning it's heart out trying to make target boost, which is 1.4bar on stock RS2 ECU and (2) because the sound is 'escaping' from the leak. The hard 'whoosh' sound is sudden release of pressure; it could be a non-standard valve as mentioned or just the leak holding pressure - i had that when a jubilee clip slipped on my RS2, it would hold to about 1bar then 'whoosh' and no pressure... Also a performance air filter will allow you to hear alot more induction noise.

Check all hoses and jubilee clips along the intake, i recently had a similar problem and it was just a jubilee clip, if one has broken visually it'll look fine - get in there and check they're all attached, tight, with no splits in hoses.

[UrS4boy]

Suggest you re-read the link I provided (now with a new photo) regarding failure symptoms, etc.:

http://forums.quattroworld.com/s4s6/msgs/20994.phtml

[wowow]

Guys, thanks a lot. That should give me enough to work on and I will get back with my findings. Just a few more request :

1/.Anyone has a picture of how the stock blowoff valve looks like ? Mine is loud and can well be aftermarket. But does that have anything to do with the over boost ? I thought the blowoff valve is only used when one backs off the gas and release the pressure in the turbo ( sorry, I am a real turbo newbie )

2/. Is the large and distinct "wee" spooling sound a sign of "leak?". It is indeed much louder than my friends rs2.

3/. I don't think my version I rs2 has a digital boost gauge. Can someone pls suggest a model to me, one that requires least modification ( on connection ).

4/. Yes, I read many threads on the connector and I will surely give that a good clean up.

5/. Other than leaks, anything I need to pay attention to on the waste gate ?

[LunarWolf]

i think you're right about the digital boost. I seem to remember one too.
The Late S2 and RS2 have the same central cpu as the urS6, and we have a digital boost output.
I could be wrong, but i too remember seeing this digital display in an (R)S2!

[UrS4boy]

S2's and RS2 dont have boost gauges

Seriously? I did NOT know that. I have driven one of the four RS2s in Canada and I am sure that I had seen a digital boost gauge in the trip computer, as shown in this photo frome the 000375 km RS2. Learn something new everyday.