Power loss - HELP!

[Educated Fool]

Acquired a 2.7Tdi 2005/6 BPP. Bought with Turbo issue - hence cheap!

Replaced turbo with exchanged, re-furbished from Drautoturbo-de. Checked all codes with VCDS, and cleared them all. At the same time checked the functioning of all systems - swirls, turbo actuator etc - all seemed fine

Problem - Car starts and ticks over perfectly - will rev, but with a sluggish throttle response. On the road no power at all until at least 2000, starts to move better around 3300 but flies like the proverbial off the shovel from 4000 towards the redline.
This is accompanied by copious black smoke when asked to accelerate.
The glow plug flashing warning comes often, as does the engine check light. Using my OBD11 reader, generic Codes P0299 (turbo boost ) and P0101 (MAF sensor ) regularly appear, can be apparently cleared.
We have tried substituting both the MAF sensor and the MAP sensor with a known good unit from a 3.0 litre of the same age - no change. At some stage in it's history the car has had some damage to the front left which has been cheaply repaired and left the left side intercooler rad bashed but apparently functioning. Visually checked all the turbo intercooler hoses (with the front bumper removed) - although ageing they appear intact. Inspected all electrical connections (disconnected, cleaned, re-made) without issue.

We have VCDS available to help, but no obvious solution. Running out of ideas! Need help! All suggestions welcome.

[swalker]

need to get live data and see what is going on,, i take i the turbo actuator was calibrated to your car? he black smoke is over fueling, whats the correction values for the injectors?

[Educated Fool]

Thanks for the swift reply. The turbo and actuator came as one pre-calibrated. However, I've no idea of the injector correction values - or how to get them.

An update though. Issue seems to be one of: electrical/electronic/sensor/ECU related (delete where applicable). Why? Well, from cold start this morning she ran as if there's no problem - power throughout the rev range and no black smoke.
After ten miles and fully warm stopped for around 10 minutes. On re-start (now fully warm) power delivery as first post, black smoke on acceleration. Needed to drive like a hooligan to make progress - revs kept above 2500-3000. If revs kept high then little or no smoke on acceleration. The fueling system gives me the fuel I need, but the power isn't there until over 2 and a half. No codes registered on OBDII. Baffled, but have to assume it is a sensor or ECU issue now - something is not giving (or reading) the correct signals.
With occassional access to VCDS and no personal experiance of using it, I need to know where and how to look for the issues. Thanks in antici...........pation.

[swalker]

with no codes i am going to say its mechanical - is it OBDII you have or eleven? VCDS either way will get you into see the offset values, channels 13 and 14 in control module 01 (engine)

[Educated Fool]

Just deciding whether or not to upgrade to OBD12...yes, I know.
Anyway, progress has been made. Following a failure to negotiate a steep hill - no power and even manic clutch slipping wouldn't do it, we looked into several possibilities. As it seemed related to the warming up of the engine we tried disconnecting the temp sensor - this may have had no effect, we shall see - and at the same time the vacuum feed to the EGR valve diaphram. This produced a total change in the behaviour. The power seems to have returned, the revs seem to respond as they should to the throttle pedal and some form of normality appears to have been restored. The suggestion of it being mechanical, as there were no related codes showing, may well be proven correct. I will try a start from fully cold followed by a decent run before I can confirm that it is behaving itself, but fingers crossed.
Thanks again for the comments.

[MFGF]

Just deciding whether or not to upgrade to OBD12...yes, I know.
Anyway, progress has been made. Following a failure to negotiate a steep hill - no power and even manic clutch slipping wouldn't do it, we looked into several possibilities. As it seemed related to the warming up of the engine we tried disconnecting the temp sensor - this may have had no effect, we shall see - and at the same time the vacuum feed to the EGR valve diaphram. This produced a total change in the behaviour. The power seems to have returned, the revs seem to respond as they should to the throttle pedal and some form of normality appears to have been restored. The suggestion of it being mechanical, as there were no related codes showing, may well be proven correct. I will try a start from fully cold followed by a decent run before I can confirm that it is behaving itself, but fingers crossed.
Thanks again for the comments.

Probably a red herring, but I'll mention it anyway. I used to have a 2005 A6 but it was the 2.0TDi. It developed symptoms similar to the ones you describe - drastic power loss, tons of black smoke, intermittently it would run fine, then run awfully. It was recovered from my office car park and it didn't have enough power drive it onto the back of the recovery truck. There were no codes stored and the Audi dealer it ended up at was stumped. They started replacing parts but to no avail (AMM, ECU, fuel filter, fuel lines, fuel tank, fuel pump). Eventually they found it was a problem with the EGR valve - the flap had become disconnected from the spindle. Sometimes it would stick open and sometimes closed. A new EGR fixed it. Yours is a different engine and year, but the EGR valve is something to check maybe?

Good luck!

MF.

[swalker]

I wasn't taking the hand with the OBDeleven - its a cheap VAG diag tool - doesnt have the power of VAGcom but a great glove box hero.
Anyway sounds like you are onto something with the EGR, hope you get it sorted soon

[Educated Fool]

Thanks for the good wishes.
Having removed the vacuum connection at the diaphram she seems to be running perfectly. We'll see how she goes for the next week or so. It would appear that there is a significant problem with the EGR valve, but removing to clean, or replacing are too involved to get into at present ... Madame has yet to forgive me for buying yet another heap of trouble (two "work in progress" Freelanders are quietly relaxing in the workshop awaiting cylinder head attention). As a result I intend to leave well alone until the others are living and breathing again. What, if any, are the medium term issues of running with the vacuum diaphram disconnected; I can't foresee any major problems, or am I being naive?
N.B. Didn't know about OBD11. Feel I may have to invest in VCDS as I'm sure this will just be the start of an intruiging(!) relationship with Emma the A6.

[geordielad1]

Mine done the same yesterday snapped egr valve new one ordered fitting tomorrow