A6 Tdi intermitent Power loss

[paulga]

Hi all. Just paying my occasional visit here hoping for some help. I am mostly to be found hanging around the Chimaera forum.

My 1998 A6 1.9 Tdi (110) has an irritating occasional power loss.

When the car is cold and it is accellerated hard it seems to go into a kind of "limp home" mode with reduced power. This resets when it is turned off and back on again. It even resets if the key is quickly flicked off and on whilst still driving (a risky strategy I know!).

The reduced power feels very much like when the MAF was faulty, which I have replaced recently.

Anyway, I have used Vag-com to look for fault codes and it comes up with this:

01 Engine
Controller 038 906 018 DG
Coding 00002
Shop# WSC 02325
1 fault found
00575 Intake manifold pressure
17-10 Control difference - intermittent

Discovering the fault code is great, knowing what it means is another thing completely!

Does anyone have any idea what this means or where to start looking for the problem.......or is this a dealer/specialist job?

Many thanks.

Paul.

Edited by paulga on Friday 2nd March 10:10

[jeffc]

Ive had boost pressure control valve on 130 tdis.. cheap fix, on a 130 its on the pipe that runs along the back of the engine held in with 2 screws.. think was £30 ish.. Ive had loads of air flow metres and also had some dodgey new ones (recon)..

[paulga]

jeffc said:

Ive had boost pressure control valve on 130 tdis.. cheap fix, on a 130 its on the pipe that runs along the back of the engine held in with 2 screws.. think was £30 ish.. Ive had loads of air flow metres and also had some dodgey new ones (recon)..

I have actually found that one of the vacuum pipes was chaffed and had a hole in it. I have repaired this and am hoping that the problem is as simple as that! I'll see how it behaves in the next few days. Otherwise I will try replacing the boost pressure control valve.

I know that the MAF is a common fault. I have replaced the MAF a couple of times in the past, once with a cheap replacement which didn't work properly, but the problem this time is different so I don't think thats the culprit.

Anyway, thanks for the advice.

[drybeer]

paulga said:

jeffc said:

Ive had boost pressure control valve on 130 tdis.. cheap fix, on a 130 its on the pipe that runs along the back of the engine held in with 2 screws.. think was £30 ish.. Ive had loads of air flow metres and also had some dodgey new ones (recon)..

I have actually found that one of the vacuum pipes was chaffed and had a hole in it. I have repaired this and am hoping that the problem is as simple as that! I'll see how it behaves in the next few days. Otherwise I will try replacing the boost pressure control valve.

I know that the MAF is a common fault. I have replaced the MAF a couple of times in the past, once with a cheap replacement which didn't work properly, but the problem this time is different so I don't think thats the culprit.

Anyway, thanks for the advice.

I think you've done the correct thing - The fault must be a leak in the intake side, making the N75 (boost control) boost the turbo too much to compensate meaning it goes into safe mode!!

My S4 was doing this at one point, and it turned out to be a leak, but in one of the intercoolers, which is harder to diagnose...

So check all those pressurised areas, incl. Intercooler if need be, and you should be fine!