3B overboost mistery

[rs200]

well my friends I have BIG PROBLEM with 3B engine... please help me with advice , because one week I try to find a problem and I can't..

when you give a contact on dash it shoes 1.9bar (on dash) , then you start the car and it drop to 0.8 bar , and they don't want to drop on 0.2 or 0.3 like it have to be...

and if you give them a little

if you go to drive the car , they go like golf 1.6 disel... the car is dead , but turbo have a huge pressure 1.9 bar (on dash) , turbo spools like immediately and in 1. gear at 3000 rpm they have 1.9 bar .

I check almost everything or replace some parts from other car which is 100% ok.

no boost leak
waste gate 100% ok , rubber inside are ok
exhaust pipes have good flow they are ok
new vacum pipes (everywhere) ok
N75 valve ok
cams ok
engine timing ok
hall sensor ok
knock sensors ok
MAF ok
barometric sensor ok
MFTS ok
today I tested intercooler and they are ok
ISV ok
blow off is new and they are ok (stock)
turbo ok
engine run ok

what can cause that problem... please help me...

THANKS

[Robatron]

Have you checked the vacuum hoses that run off the back of the inlet manifold?

[rs200]

and if you give them a little gas they can go to 1.2-1.4 bar , but car is still on place , not in driving.

I dont have other 3B ECU to change and see if the ECU is a problem.

and I didn't check throttle position sensor... can they be a problem? I dont know... I'm out of my mind , maybe next week I be i psihical hospital ...

did someone here have simular problem?

[rs200]

yes I did it , and buy a new one vacum hoses in all engine bay... all new and check each one of these..

[rs200]

and here is a short video of my problem... well on 0.25second you can see that turbo hit 1.2 bar , and car is running in place..

http://www.youtube.com/watch?v=JJKJIuUhty4

if you go to drive , they are 90% of time at 1.9 bar , and turbo want to kill him self how did they pres the air, but car don't go like it have to be...

[UrS4boy]

and here is a short video of my problem... well on 0.25second you can see that turbo hit 1.2 bar , and car is running in place..

http://www.youtube.com/watch?v=JJKJIuUhty4

if you go to drive , they are 90% of time at 1.9 bar , and turbo want to kill him self how did they pres the air, but car don't go like it have to be...

First of all, your boost gauge reads absolute pressure. This means 1.01 Bar is basically atmospheric pressure. 0.6 or 0.7 Bar at idle is correct. On idle your engine is generating a vacuum, i.e. lower than atmospheric pressure (about 1.01 Bar). Secondly, you can not generate any substantial boost above atmospheric pressure without a load on the engine, i.e. sitting still not on the road you are lucky to get that momentary 1.2 Bar (0.2 Bar of positive boost).

3rdly: I think I see a rip in the hose between the intercooler and the long black metal tube that goes to the throttle body. I am sure I see a crack 3 "valleys" to the right of the left end of that hose.

Good luck.

[newsh]

With those "Michelin Man" hoses you can get a split under the metal wire rings

[rs200]

i don't get it what are you want to say...
is it matter if we talk about atmosferic or absolute pressure...

absolute pressure on idle must be 0.2-0.3 on audi 200 20v, but not 0.6 or 0.7 like it is on this car.

I bring camera to black hose that you can see that engine expand that black hose , like ballon . do you understand?

go to your engine and try to give them a gas , and your hose will not expand like ballon...

can ECU or trottle position sender do problems like that is? because this are 2 things which i didn't check..

[newsh]

Do you think the cam timing may have slipped?

[rs200]

cam timing are 100% ok...

before few minutes I gone to check throttle position sensor and they are 100% ok too

my brain will blow away .

[newsh]

Did you do a compression test?

[rs200]

no I don't have a tester, but will find it tomorow and check that too. thans for advice. now I remember something-when my cilinder head was bad it shoes 0.6 bar on dash, the valve sats was bad, maybe that 200 20v have the same problem.

but my car was going much better than that one, and have a normal positive boost. soo I don't belive that is a problem.

[newsh]

Yes, I'm thinking you have a bad inlet valve and so you have pressure coming back into the inlet. It certainly sounds wrong on the video and the noise gets louder as you open the throttle?

[rs200]

I think that found the problem... not 100% but 95%. the MAP sensor in ECU have damage, because I put my boost gauge in that car ,and shoes the same pressure on idle like my car. -0.8 (0.2bar on dash.)

that means the engine have NO LEAK, and ECU have wrong info about boost , and give wrong fuel and overboost... exacly everithing is wrong...

good thing is that we will do AAN conversation on that car , and we allredy have AAN ecu. but first they must work fantastic on 3B ECU.

[rs200]

thanks everybody for help , and special thanks to : newsh