Allroad 2.5 TDi AKE boost problem

[Llewelyn1966]

I'm chasing running issues on a 2.5 TDi Allroad with the AKE engine. Since I had it, it has had an intermittent low power when pulling hard (e.g. uphill). If I backed off and slowed down it would recover and pull normally.

It's now been standing for a bit (I've been busy and have other vehicles) and now it won't rev over about 2800 rpm, and smokes quite a bit. Previously, it only went low power when climbing hills so something new has gone wrong or the original problem has got worse.

Since buying it, I have changed the MAF for a new one, changed the fuel filter, had the unit out of the tank to check if there was a blockage there leading to bad fuel supply. There's never been a check engine light.

I have VCDS lite and have looked at fault codes, and got a persistent 00519 27-00. I have replaced the MAP sensor on the intake with a new one, and checked continuity between that and the ECU.
Only 3 of the pins on the sensor are connected. Is that normal for an AKE engine? There's no sign of another wire, e.g. if it had broken and the car was running before with just 3 wires, so I don't think that is the main issue.

I've also tested the turbo N75 actuator with a vacuum tester, it works and has no vacuum leak. The turbo isn't seized, it turns freely when pushed gently with a finger. I suppose in theory 2 halves of the turbo could be separated but I think I'd have noticed.

VCDS reports boost pressure as invariant and the same as atmospheric pressure, and N75 duty cycle is stuck on 15%. I've tested the vacuum solenoid thing, it has 16 ohm resistance so is not shorted or open circuit. I have a feeling the issue is somehow connected with the MAP sensor, since it's not showing any change in boost pressure.

What am I missing? Is there any other pressure sensor, beside the one below the passenger headlight? What else can I check?

[Crasher]

I can’t check at home but I don’t think the AKE uses the sensors temperature signal so does not need the wire. Is the MAP sensor a genuine or Bosch part?

[sandistt]

I'm chasing running issues on a 2.5 TDi Allroad with the AKE engine. Since I had it, it has had an intermittent low power when pulling hard (e.g. uphill). If I backed off and slowed down it would recover and pull normally.

It's now been standing for a bit (I've been busy and have other vehicles) and now it won't rev over about 2800 rpm, and smokes quite a bit. Previously, it only went low power when climbing hills so something new has gone wrong or the original problem has got worse.

Since buying it, I have changed the MAF for a new one, changed the fuel filter, had the unit out of the tank to check if there was a blockage there leading to bad fuel supply. There's never been a check engine light.

I have VCDS lite and have looked at fault codes, and got a persistent 00519 27-00. I have replaced the MAP sensor on the intake with a new one, and checked continuity between that and the ECU.
Only 3 of the pins on the sensor are connected. Is that normal for an AKE engine? There's no sign of another wire, e.g. if it had broken and the car was running before with just 3 wires, so I don't think that is the main issue.

I've also tested the turbo N75 actuator with a vacuum tester, it works and has no vacuum leak. The turbo isn't seized, it turns freely when pushed gently with a finger. I suppose in theory 2 halves of the turbo could be separated but I think I'd have noticed.

VCDS reports boost pressure as invariant and the same as atmospheric pressure, and N75 duty cycle is stuck on 15%. I've tested the vacuum solenoid thing, it has 16 ohm resistance so is not shorted or open circuit. I have a feeling the issue is somehow connected with the MAP sensor, since it's not showing any change in boost pressure.

What am I missing? Is there any other pressure sensor, beside the one below the passenger headlight? What else can I check?

Trie to change the engine ECU..... sometimes they can be faulty, and don't do the process right..... Why not, you don't have nothing to loose if you just tried..... Other thing, disassemble the turbo wanes..... clean them, or make sure they move freely....

Sent from my FIG-LX1 using Tapatalk

[Crasher]

Back when we were doing a lot of these at around 3 years old we had a lot of odd running problems which were cured when we changed the ECU. Obviously this is quite a big step but the first time was when I had talked to my friend who was the local Audi dealer service manager and he said they were changing a lot of them. The only problem is the exchange Audi part 4Z7 997 401 AX is obsolete from Audi UK and even though Audi Tradition in Germany have stock, they won’t send to the UK because they can’t cope with Brexit…