Noise when turbo spinning accompanying power reduction.......

[jamesmc1]

Sorry to bore everyone with another power loss problem but I went down this painful road 6 months ago which resulted in the Turbo being changed to cure the problem. Since then the car (2001 TDI 130bhp) has ran okay apart from recently when it has suffered from a reduction in power. The symptoms of the problem are:

1) In fourth gear it is very hard to pull over 3000rpm and get the car to go above 90mph (in lower gears will go over 3000 rpm).

2)When changing gear there is no boost for a couple of seconds then the turbo ‘kicks in’.

3) When the turbo does ‘kick in’ it is far more noisier than it used to be and sounds like air is leaking from somewhere ?

4) On one occasion the car went into 'limp mode' but this has only happend once in a month.

I’ve taken the undertray & bumper off and followed the 3” pipe from the bottom of the turbo through the intercooler and back again but cannot find any air leaks. The only concern I have is there was a slight trickle of oil at where this pipe comes out the bottom of the turbo and was wondering if it could be the oil seals in the turbo failing causing the Turbo to make the noise ?

Humble appologies again for this post on a 'frequent topic' but I've read all similar posts and still cannot get to the route cause of this problem, any idea's ?

James

[bobmac892]

I had a 51 plate 130 PD TDi that suffered similar symtoms. VW Garage changed the turbo hose, one that fails regularly apparently. and the problem was cured. Before the fix my motor sounded like an asmatic Darth Vadar when pushed hard and the turbo was being made to work.

Hope this helps.

[Lex Luthor]

The only concern I have is there was a slight trickle of oil at where this pipe comes out the bottom of the turbo and was wondering if it could be the oil seals in the turbo failing causing the Turbo to make the noise ?

Oil in the inlet tract after the turbo is normal and its source is the CCV system.
Sounds like you have a boost leak and low boost pressure can cause oil to leak from the turbo seals.
Check under the long pipe that runs across the engine bay near the bulkhead.

[jamesmc1]

A had suffered similar symtoms a year ago (i.e. lack of power that sounded like an asmatic Darth Vadar) and traced it to the pipe that comes out of the bottom of the turbo running to the intercooler. The replacement pipe part was aprx £70. Furthermore I have checked the pipe running accross the engine by the bulkhead. When checking the connector going into the EGR valve it was loose so pulled out the clip only to find half of it missing so I thought I had found the leak. I replaced te clip but it was still the same.

I've placed the car in the hands of a VW specialist who has checked the fault codes and found an 'underboost' logged but cannot find any air leaks. Current train of thought is turbo boost control valve being faulty, is this the N75 ?

James

[jamesmc1]

The VW specialist replaced the 'Turbo boost control Solenoid' (N75) and cleaned out the EGR valve. This cured the problem in the car was a lot better in between gears and would go over 90mph no problem.

A couple of weeks later the car is regularly failing to go over 90mph. When this happens in 5th with the accelerator flat to the floor there is like a jerkiness in the power. Eventually limp mode 'kicks in' requiring the ignition to be turned on \ off. When turning the ignition back on the car tends not to fire up the first time but will the second time.

Accompanying this the other day I used the car for a short 2 minute journey. Stopped the car and restarted it only for it to go straight into limp mode (would rev but no turbo). I pulled over restarted the car (would not start first time) but this time would not rev at all and when attempting to the engine would sound really rough. I let the car tick over for a couple of minutes and tried revving again and it was fine.

I've put VAG COM on and it's reported 17964/P1556 - Charge Pressure Control: Negative Deviation Intermittent. My next step is to replace all the vacuum hoses so as to rule out an air leak other than that are further suggestions ?

James

[audi a4]

hi mate my audi a4 pd tdi 115 bhp has the same problem and im getting fed up of spending money on checking everything so please if u figure out the problem pls let me know or if anybody else knows pls it would be great help. iffi

[jamesmc1]

Before I changed all the hoses the problem got excessively worse. When on the Motorway going up a slight incline the car started to go slower and slower eventually down to 50 mph i.e. not just limp mode. I had to pull over onto the hard shoulder and restart the engine in which it would cough and splutter when trying to rev so I left it for 20 seconds tried reving again and it was okay.

In the end I took the car to a fuel injection specialist who has the Bosch diagnostics, not cheap at £65 an hour. They put diagnostics on and no fault codes were found however upon inspecting the engine they found the anti shudder valve mounted on the side of the EGR valve was faulty and some times was not letting air into the engine. This was replaced and for the last 2 weeks the car has been back to normal.

Hopes this helps.

James