A3 TDI turbo problem

I have a late 2000 A3 TDI 110hp and keep having boost problems with the turbo. When under full load, typically 3 - 4,000 revs going uphill on full throttle the power suddenly reduces which is obviously a problem if overtaking. If, whilst still moving and in gear, the ignition is turned off and back on so the car restarts, it is back to normal. There is no engine management light. My local garage has had a play, trying replacement boost valves, but unsuccessfully. They have now got an Audi diagnostic reader and come up with the Audi fault code 17965 (turbocharger pressure control limit exceeded - turbocharger wastegate regulating valve). They had a word with the local Audi dealer who said it could be a cracked body to the turbocharger, a problem with the intercooler and a lot of perhaps and maybe. I've got the car booked back in to the garage to take off the turbocharger, as I am loathe to let the main agent loose in a speculative manner at £££££ per hour, and have a physical look but I thought I would try you folk to see if it was a known problem. This is my first post here so please excuse any breach of protocols.

Paul

Hi. I have a 2005 TDI with the same problem, the turbo is over boosting, and makes the limp mode to kick in, Im investigating at this moment I will post my results, I have the equipment to check them, also I have an other a3 same car same year, which is running ok so Im comparing data, to find the fault!

Cheers

I now understand it is likely to be caused by carbon build up affecting the variable vanes and therefore causing overboosting. There is apparently a product which can be used to dissolve or clean off the carbon but it is not guaranteed, the alternative is a recon turbo which is the route I shall go.

Hi again, just doing some tests, if I move the vanes actuator using vacum the flow changes,moved the top end adjusting screw, to see if I can lower the pressure down. then took some ridings.

The good A3 with the car standing (not driving)

RPM -- Desired boost pressure -- Actual boost pressure

1000 1030 989
2000 1061 1030
3000 1163 1122
4000 1234 1295

BAD A3

1000 1030 1000
2000 1061 1030
3000 1163 1200
4000 1244 1826

its ok up to 3000 revs then it goes mad! but now with the little adjustment and cleaning the waste gate at least does not triggs the limp mode (for now).

Thanks for your advice, I thought about the turbo replacment, but I have to make shure is the one causing the problem, before replacing.

Still to check the condition of the pressure sensor which I can't find, I think is in the intercooler, I have a look now, if is easy to remove I might change it over to have an other scan later.

Hi again!, found the sensor is in the lower n/s intercooler hose, swaped over, no change still the same, new turbo about 1K! from main dealer,340 recond 570 new aftermarket

the original fault code was, 16618 boost pressure regulation limit exceeded over boost condition p0234

hi great these pages where you all talk one can learn a lot,
are there any common problems with these turbos!
I just bought a 1998 A3 TDI

in 1st it seems ok
2nd it will cut the turbo out
120km turbo will stop

well i changed the air flow sensor that did nothing, checked fuel nothing

been thinking about pulling turbo off,

then tonight i found it had been in a crash repaired and the intercooler was damaged so they guled it together and put it back,

all vacum hoses and sencors were checked as well as waste gate rod movement,

i will replace the intercooler and see what happens, i have a feeling the turbo will still need to come off,

she is also very bad for black smoke so injectors might be changed after the intercooler and turbo are sorted,







intercooler was leaking oil thats why i looked at it

Hi had the similar problems with my tdi, i did a number of things to help sort the boost "problem" out. I cleaned the egr valve as it was filthy and also one the pipes leading towards the turbo had split.

I have now replaced the intercooler beacuse it was guled together and was leaking so bad all boost was being lost,

so when your boost is lost fuel ratio is very high with low air, ecu will notice this after 3grand and place car in limp mode,
stop and restart and car will reset,

boost loss will result in black some no power and limp mode cutts in,

after a 30min thrashing it stoped black smoke and goes like a normal tdi pulling all the way through the rev band,

now the car is back to perfect with full power and no smoke

I did replace all rubber pipes, fuel filter, MAF, air filter before i found what was the problem tho,

even a lap to reading fault codes could not tell me that the intercooler was the fault

where is the egr valve and what does it do mate