Ive come here as I'm at a loss for this problem.... a month ago the turbo shaft sheared in two on my '06 Octy 2 which was duly replaced by a new item by my mechanic. There's now a bizzare fault - engine behaves normally around town with normal boost etc but on dual carriageways etc boost just switches off at around 60mph in top gear: the turbo shutting down is quite apparent with a sudden decrease in power. Any ideas???

Vehicle was mot'd at the same time and was ok on emissions and such like and is still returninhg 50-60mpg on long journeys, not that I've done many of them lately :(

The first thing i would check is to see if the intercooler pipe (s) aren't collapsing, as this would cause a sudden drop in boost.

Does the boost return after the loss or do you have to cycle the ignition?

 

I'm just thinking aloud that it could be an overboost condition causing limp mode either due to jammed turbo vanes or a faulty MAF sensor.

 

Due to the recent turbo work I'd suspect turbo.

 

I think the turbo is pneumatically governed, perhaps the pipe is split.

The turbo is goverened by vacuum  the engine light has now come on so a complex tale has become more complex. :( Octy is still perfectably driveable around town

ok took my octy 2 out for a trip today. ECU is putting engine into limp mode, boost is 'late'. Engine light is on. Any ideas??? else my beloved Octy is going to die.

The original fault was the turbo shaft sheared. Fuel cons is very low 68mpg from Wallsend to Fife.

 

Les

Have you checked all the control pipework?

 

I've read many times about split/chaffed/loose pipes causing turbo/limp issues.

Bad map sensor maybe

First question is what sort of turbo was fitted? Original part from Skoda or something else?

 

Have you run a diagnostic scan with VCDS or similar to determine the exact source of the fault?

 

Was the actuator linkage checked before the new turbo was installed? If that's incorrectly adjusted, the car can go into limp mode due to over/under boost because the vanes are going out of range.

 

Check that all the lines and fittings to and from the turbo are sound: given that a bunch of stuff will have been disturbed to fit the new turbo, it's possible something was put back in incorrectly.

 

Check for oil in the intercooler: you could have some oil in here if the turbo shaft split and poured oil down the intake. Probably not the root cause but worth checking for.

 

Check the condition of the MAP sensor. If you have VCDS, take the car for a drive and log MAP actual and MAP requested - make sure you trigger the limp mode during the drive to monitor the behaviour during the event.