Octavia L&K 110 TDI estate 52 reg.Intermittent turbo issue..

[CraigG]

Hi all.

My 52 reg Octy with 93k has a slightly annoying fault.Every now and again the turbo dies.Normally when accelerating or going up hill.Once the turbo dies all i need to do is turn the ignition off and on again,which then resets the turbo and full power resumes.No error codes,faults or dash symbols. Anybody have an idea what could be causing this issue?

[pauldazzle]

Sounds like sticky turbo vanes. What are you using to read codes/faults?

[CraigG]

Im using a VAG com unit OBD2 too read the errors and codes.

[Tech1e]

Sticky turbo for sure.

[pauldazzle]

Im using a VAG com unit OBD2 too read the errors and codes.

You should be getting a fault code as the the ECU is going into limp mode. Generic code readers don't recognise a lot of VAG codes, but VCDS/Vagcom should be telling you what's wrong. Sticking turbo vanes usually causes an overboost code.

[pikpilot]

There was no code stored when I had this issue with sticky vanes.

[mbames]

Time to get the Mr Muscle out.

I am re-treating mine this morning as a few more limps have been occurring. Oddly it was fine over the winter, but since the weather has been a bit warmer it has started to play up again.

[CraigG]

I am NOT getting any fault codes, alarms or going into limp mode.I just loose the turbo with no warning.Blip the ignition on and off and the turbo returns with no problems.It may not happen again for weeks..

[trundlenut]

I am NOT getting any fault codes, alarms or going into limp mode.I just loose the turbo with no warning.Blip the ignition on and off and the turbo returns with no problems.It may not happen again for weeks..

Just to be clear, you are using VCDS?

[mbames]

I am NOT going into limp mode.

tends to disagree with your next statement:

I just loose the turbo with no warning.Blip the ignition on and off and the turbo returns with no problems.It may not happen again for weeks..

mmm, the turbo dropping out and being restored by cycling the ignition is limp home mode. Mine would do this and early on it never used to log any codes.

I am puzzled why you ask a question and then ignore the same answer we are all giving you?

Edited 25 June, 2013 by mbames

[CraigG]

Im using a - Autel MAXSCAN VAG405 unit to read the errors and codes

[CraigG]

@ mbames .. so what your saying is every time the turbo drops out the car is in limp mode.Im not ignoring the answers.If i get no alarms or errors how do i know the car has gone into the so called limp mode.It is still driveable but just doesnt have the kick of the turbo.The car will still reach motorway speeds but its just slower to get there..

[trundlenut]

A quick spot of googling suggests that it should pick up all codes but it may be worth finding someone near with full fat VCDS just to make sure.

If you get reduced performance which disappears when you cycle the ignition then that does indeed sound like limp mode. When this problem occurs is it at about 3k rpm?

[trundlenut]

@ mbames .. so what your saying is every time the turbo drops out the car is in limp mode.Im not ignoring the answers.If i get no alarms or errors how do i know the car has gone into the so called limp mode.It is still driveable but just doesnt have the kick of the turbo.The car will still reach motorway speeds but its just slower to get there..

limp mode = reduced performance. The ecu reduces the amount of fuel being injected to stop damage occurring (I think that's how it works), which means tractor like performance.

[mbames]

Generally if cycling the ignition causes the turbo to come back to life, then the car will have dropped into Limp.

It does this to protected itself. Normally the cause is sticky vanes in the turbo producing too much boost. Try logging request and actual MAP and see if they follow a smooth and similar shape. In my experience when the turbo is just staring to get sticky, then no faults are logged, but once it becomes worse then the codes start to appear.

If the car was slow all the time and cycling the ignition made no difference then contenders would be the MAF, MAP sensor, n75, vacuum leak.

[trundlenut]

I've faults without warning lights and warning lights without faults, it is not an infallible system.

[mbames]

I should say I cleaned my turbo again this morning, and it amazing the difference in performance. You don't notice the performance drop as it gradually fades away, but once vanes in the turbo move freely it is totally transformed!

[CraigG]

Ok thanks for the advice and answers.

mbames -- how exactly do you clean out the turbo to eliminate the sticky vanes.Thought i would try this first if its a simple job.Cheers again..

[mbames]

Search on here for Lofty's Mr Muscle guide.

However before doing that check to see how smoothly the actuator on the turbo is. Do you get:

- smooth travel

- full travel

- any creaks & groans

- can you push it with your thumb, or do you need to apply a vacuum to make it move

The job takes a couple of hours. Basically you remove the EGR recirc pipe and then use some flexi pipe to squity some mr Muscle into the exhaust side of the turbo and then you need to exercise the actuator for the next couple of hours.

You will need some socket mounted allen keys to undo the EGR recirc pipe, and you can remove the EGR valve assembly to improve access.

[CraigG]

Cheers mbames ill have to give that a whirl.