A3 TDI turbo problem

[Paul F]

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

[Gabrielsande]

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

[Paul F]

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.

[Gabrielsande]

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.

[Gabrielsande]

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

[Gabrielsande]

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

[barryareef]

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.

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[fourringsrus]

Hi to all above,though bob 1698 seems to have sorted his turbo/intercooler issues,please before spending lots at poorly educated garages or unsure main dealers check out the many recent threads about limp mode on the tdi engines
The turbo's vanes are most commonly sticking and causing overboost situations just like you all refer to.
This in most cases is cured by replacing the turbo with new or re-conditioned item.
Hope this is helpfull
Stuart

[bob1698]

I got an AUDI A3,

When driving over 3000rpm the turbo cut out, and limp mode came in,
after stoping the car turning it off and restarting it the worked ok but only up to 3000rpm

When i asked people they said MAF/ turbo and many other things,


When I looked myself I found the intercooler was damaged

I replaced the intercooler and the car now works fine,

[Phatboyruss1]

Cheers bob1698

So it might be the seal then, worth a go replacing both I suppose, thier just over a tenner each... cheaper first try solution and it needs doing anyway.

Anyone else got any other ideas? I'm going to try replacing the fuel filter, don't know when it was last changed...