Turbo Questions

[mrploppy]

I'm still struggling with EML and the occasional EPC light (and limp mode) on my Audi A1 1.0 TFSi. Local garage was hoping that it would eventually sort itself out and that the errors starting happening because it had been sat idle for a few weeks. Regardless, I've now got myself a code reader so I can do what they charged me £60 to do i.e. clear the codes and remove the warning lights. BTW, I realise this isn't a good long term solution.

To my untrained eye, the car seems to perform pretty well, even when the EML light has come on. On the odd occasion the EPC light has come on, it's definitely got reduced performance, which I presume is limp mode.

I look at the fault codes regularly. I've had a mixture of
P334B - Charge Pressure Control Actuator: Mechanical Malfunction
P2279 - Intake Air System Leak (once)
P0299 - Turbo Charger Underboost (causes limp mode - pretty sure)

The P334B code is mostly always present and the others occasionally so I'm assuming the real problem is the actuator, and that the others are side effects. The most recent I've had is the P0299 but it may have happened before and been cleared by my local garage.

Maybe someone could explain (because I don't know much about turbos). I know that the actuator is what opens and closes the wastegate. If there's underboost then I presume the wastegate is open. If the wastegate is open, why would the car go into limp mode. I would have thought that underboost would be pretty safe for the engine, whereas overboost would be the more serious problem. Unless, of course, the actuator is not moving freely (but the, I've never had an overboost error). Am I missing something?

Also, I will need to do another 100mile trip in a few days (mostly motorway) - I have no option but to use my car. Given that there may be an underlying problem with the actuator, how should I drive the car? Should I restrict speed, acceleration, revs, deceleration?

Any advice/clarification gratefully received.

Edited by mrploppy on Monday 10th May 19:46

[liner33]

Ross Tech says this http://wiki.ross-tech.com/wiki/index.php/P334B/013...

So ideally check the boost pressure you are getting

I'm not familiar with these engines, on some you can replace the actuator separately on others its part of the turbo

This video may help you understand what your are looking for/at

https://www.youtube.com/watch?v=vejleZkINs0&ab...

[mrploppy]

Thanks. Unfortunately, I don't think I have the technology to check the boost pressure I'm getting.

I still don't get why an underboost is dangerous enough to trigger limp mode though.