please help, loosing boost on my 1.9tdi

[Neil Conlay]

right here goes, i'll try and explain this the best i can.

when accelerating through the gears in my a4 avant tdi se (standard) it boosts fine, i go into 5th gear no problem, it boosts fine, then when i hit about 78mph it just dies, as if there is a limiter, it wont go over that speed, then when i slow back down to a junction etc and try and pull away there is no boost at all, but when i turn the engine off and turn it back on again everything is fine, someone told me it might be something to do with the accelerator pedal because it is electronic??? i have no idea what to do, can anyone help? thanks in advance. Neil Conlay

 

[stu_m]

The car is going in to limp home mode you need to find out why it could be a number of things

 

[Widemonkeys]

You need to get it scanned for fault codes, mine was doing it a few weeks ago and it was a pin head sized hole in the hose.

 

[Neil Conlay]

ok i'll get it scanned today and see what it comes up with, thanks.

 

[marktdisport]

maybe turbo vanes need cleaning....

 

[AudiLeon]

maybe turbo vanes need cleaning....

Agreed. Very likely. Got this on the A3.

 

[quattro tony]

Id agree too, very common on the pd range, more likely will be a overboost fault code logged. Sticky turbo vanes seems to be the problem as long as everything else looks ok. Some people have managed to strip their turbos down and clean/ free them up with success, others replacement is necessary and ive read about kits u can get to clean them out without removing the turbo. When u turn the ignition off and on you reset the ecu and take it out of limp mode until it overboosts again. Its pretty dead when it happens !

 

[stu_m]

Id agree too, very common on the pd range, more likely will be a overboost fault code logged. Sticky turbo vanes seems to be the problem as long as everything else looks ok. Some people have managed to strip their turbos down and clean/ free them up with success, others replacement is necessary and ive read about kits u can get to clean them out without removing the turbo. When u turn the ignition off and on you reset the ecu and take it out of limp mode until it overboosts again. Its pretty dead when it happens !

havent others on here cleaned them with mr muscle oven cleaner and had good results?

 

[Neil Conlay]

i scanned it and found no fault codes at all, my mechanic says it might be the data transfer box under the accelerator pedal? do you think this might be the case?

 

[stu_m]

if its going in to limp home mode you should be getting a code up

what was it scanned with ? vagcom or audi dealer tool or a hand held scanner

 

[murran]

sounds like an overboost fault.

 

[quattro tony]

As above still. I would be looking at live data if u have vcds and seeing what the turbo boost is reading and if its within limits when the fault occurs. From my experience if the electronic throttle pedal goes faulty the glow plug light normally starts flashing and the car will just idle and do nothing else.

 

[Neil Conlay]

i think it was just scanned with a hand held scanner, i dont have big money to take it to a main audi garage, there was no fault codes at all, would this rule out the accelarator pedal but could it still be that the vanos would need cleaning?

 

[stu_m]

I had mine scanned with a hand held scanner when I had boost problems and no codes yet with vagcom it came up