annoying boost problems!

[Welleh]

hi people!
before i renovated my car i had one really annoying boost problem, what happened was is it would boost to a bar up to 4000rpm in any gear, then after the 4k mark it would cut back to 7psi (mechanical boost i think!) and from and after it had cut back, it would boost 7psi at whatever revs any gear untill i recycled the ignition or restarted the car. since then i have had the engine out to clean up, change steering rack and do some other stuff, however doing that i found 3 big pulley gueldges in the IC so ive changed that aswell, which i thought would be the problem! but to my dissapointment on saturday is wasnt! . ive also changed the WGFV in that time aswell. now the car is back together and running the problem still exists, and i'm off to nurburg in a week and a half! (EEEEEK!), i'm now left clueless to what the problem could be and i cant read any codes off the ecu as the vag-com lead i bought diddnt seem to want to work! any one have any ideas? ive checked the barometric pressure sensor and got roughly the same readings as everyone else's that worked, but i don't see how resistance can tell that, was gunna check it on the oscilloscope but no-one else put there readings up, someone said about adjusting it to fool it but i could'nt find out how! as i have limited access to the internet! anyone have any ideas what could be wrong with my car! i'm willing to go to desperate measures to get it sorted and running sweetly before nurburg!

Thanx in advance
Steveo

[Welleh]

no one have the foggiest?

[s2dude]

hi people!
before i renovated my car i had one really annoying boost problem, what happened was is it would boost to a bar up to 4000rpm in any gear, then after the 4k mark it would cut back to 7psi (mechanical boost i think!) and from and after it had cut back, it would boost 7psi at whatever revs any gear untill i recycled the ignition or restarted the car. since then i have had the engine out to clean up, change steering rack and do some other stuff, however doing that i found 3 big pulley gueldges in the IC so ive changed that aswell, which i thought would be the problem! but to my dissapointment on saturday is wasnt! . ive also changed the WGFV in that time aswell. now the car is back together and running the problem still exists, and i'm off to nurburg in a week and a half! (EEEEEK!), i'm now left clueless to what the problem could be and i cant read any codes off the ecu as the vag-com lead i bought diddnt seem to want to work! any one have any ideas? ive checked the barometric pressure sensor and got roughly the same readings as everyone else's that worked, but i don't see how resistance can tell that, was gunna check it on the oscilloscope but no-one else put there readings up, someone said about adjusting it to fool it but i could'nt find out how! as i have limited access to the internet! anyone have any ideas what could be wrong with my car! i'm willing to go to desperate measures to get it sorted and running sweetly before nurburg!

Thanx in advance
Steveo

VAG COM should be first port of call.....find someone local on here who has it wokring and get the car tested.....

SOunds like it could well be a boost leak...

Heav you done a boost leak test?? search the forum for boost leak test kit and test all hoses and joints...
I had a very similair problem and it turned out ot be e split hose opening out under boost and loosing pressure.


MFTS?? Have you tried unplugging it and seeing if the problem goes away??

Vacuum test the wastegate.....or again ask another forum member local who has the kit.......

Where are you based>>??

[Welleh]

based in portsmouth in hampshire, done a boost leak test, its all fine tried it up to 1.5bar, vag com; dosn't seem to work with the cable ive got! so it would be handy to try someones! (don't mind travelling and cash involved!!) MFTS; i'll try unplugging it asap! checked the wastegate diaphram, looks good, haven't vac tested it though, although if it was a wastegate problem it would boost fully untill 4 grand all the time not just once i thought?

ta
Steveo

[stevieyid]

Just a thought mate but have u checked your MAF? I had boost problems and all it turned about to be (thanks newsh) was either dirty connections to the maf or the MAF was not tight enough. Car pulls like a train now.

[Welleh]

not tried maf yet, do you mean the heat ring or the actuall terminals on the maf? if so i'll quickly do that now!

[s2dude]

based in portsmouth in hampshire, done a boost leak test, its all fine tried it up to 1.5bar, vag com; dosn't seem to work with the cable ive got! so it would be handy to try someones! (don't mind travelling and cash involved!!) MFTS; i'll try unplugging it asap! checked the wastegate diaphram, looks good, haven't vac tested it though, although if it was a wastegate problem it would boost fully untill 4 grand all the time not just once i thought?

ta
Steveo

Wastegate needs vacuum testing...visual will not do it!!!I'm oop north so you may want to post a request for assistance by a southern forum member....

This guide should help you a LOT!!!

http://www.sjmautotechnik.com//trouble_shooting/20vboost.html

[stevieyid]

Mine was not air tight. I didnt even notice but the o-ring was not tight so sir was getting in. I think this was causing my boost problems as hot air was getting in therefor raising the inlet temps. Why not try to get across to QST if all else fails?

[Welleh]

cool cheers, looks like i'm gunna be working late! i'll report back later!

[nip]

mine was abit like that until today, it was the small pipe on the back engine the 1 thats about 4inch long and 1inch thick, i think it goes into the idle stabelizer, well cut a long story short it was loose well anoying , hope this helped

[shark_S2]

hola, it he does not allow me to create a new topic, my problem is that the alone turbo works to 0,2 bar and this one quite checked, but it(he,she) is still equal, another day in the evening I me work to 1,2 but only a few hours, in the night again(afresh) to 0,2 that someone helps me please


My Englishman comes from a translator

[martinjs]

based in portsmouth in hampshire, done a boost leak test, its all fine tried it up to 1.5bar, vag com; dosn't seem to work with the cable ive got! so it would be handy to try someones! (don't mind travelling and cash involved!!) MFTS; i'll try unplugging it asap! checked the wastegate diaphram, looks good, haven't vac tested it though, although if it was a wastegate problem it would boost fully untill 4 grand all the time not just once i thought?

ta
Steveo

If your stuck for vag-com you can pull the codes easily using a 12v led or bulb, instructions on how to do this are on s2central.

[Welleh]

tried the bulb aswell, that dosn't seem to work!

[Welleh]

right after some work, replaced wastegate diaphram,
although it was not leaking under vac from top cap, it did look tired,
wastegate piston is loosing average of 3psi under 1.5bar regulated pressure, cleaned maf, terminals and loop,
cleaned mtfs although haven't tried it with it unplugged yet as i'm in the process of putting the wg back on,
retested the boost system, held 2bar (with ecu pipe bunged not to damage map sensor) and having to hold the dipstick in! (lol was smokey after a start!), any other things to try, attempted to pull codes with led, forgot to get resistor from work! so will report back later!
cant believe i have < a day to finish car! LOL anyone have any other ideas? or fancy earning some money tomorrow afternoon in portsmouth with a vagcom lead a lappy and some various bits from there car! name a price - 07774573686

Ta Steveo

[AndyP]

Has the car ever run right whilst you've had it? If so what did it boost to? If it's boosting to 1bar and above then it sounds like it's been chipped as std boost for a 3B is 0.7bar which is about 10psi. Some of the chips you can buy off E-bay are ex-race chips and have the diagnostic functions removed, this could be why you can't get at the error codes.