Hi guys please help if you can i have a AEB 1.8t 1998 a6 avant which is not boosting at all i thought it was a little slow when i bought it so changed the divert valve, with no effect then checked the turbo which seems to spin freely so not seized even checked when engine running, so i have fitted a digital boost gauge which shows -6 on idle then goes to 0 when driving then back to -6 when i lift off, there is no noise at all from the turbo or smoke from the rear and I'm stuck for ideas apart from changing the turbo please help

 

sounds like your in limp mode

 

Agree. Maybe that you are in LIMP mode (engine turns off the boost). Check for codes with a vagcom and reset any there. If you are in LIMP, that will fix the problem.

 

Sounds like a vacuum leak a whole lot more then limp mode... Should read -15ish I would expect. Spray all the boost/ vacuum lines w/ carb clean if the idle changes at any point then the leak is somewhere near that because it will pull the carb clean in and richen the fuel mixture for a second. If it were limp mode I don't think you could make it even hit 0psi cuz the waste gate would be open all the way from my little understanding of our cars limp mode. (that and I have a 2.8)

 

sounds like a leak to me too...

 

thanks for the pointers guys i wll take the hose's off at the weekend and try the carb cleaner see if hat works may try to get a copy of vag com too see if that sheds any light

 

i would say vac leak or you have the boost guage in the wrong spot or something

a4's sit at about -20 at idle.... limp you will make it to +5

or your guage is garbage or not calibrated

 

i no the gauge is working took it of a pug i have which boost's to 14psi

 

got an update on this jim1000?

 

hi guys yeah sorry for no further post's had pc trouble, well the update to the car has been money and time spent and still playing up, so far removed the turbo found no wastegate door so new turbo went for ko4 went for a remap (@chipped uk) found standard map showing 216bhp but had a boost problem, so told my maf was gone replaced maf and still finding boost problem, then told i had boost leek from chipped uk looked through the boost pipes seems ok but ordered silicone pipes to see if this sorts the problem boost gauge now showing -12 and plus 12 psi upto mad boost spikes of 26psi where the car just shuts down