Turbo Questions
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Discussion

mrploppy

Original Poster:

27 posts

100 months

Thursday 13th May 2021
quotequote all
Sorry for posting this again. Posted in the Audi forum first time, but probably should have posted here because it's not unique to Audi. Had very few responses in that forum but couldn't find a way to move it. Anyway ...

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 then, I've never had an overboost fault code). 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.

finlo

4,236 posts

226 months

Thursday 13th May 2021
quotequote all
Probably seized variable vanes in the turbo doubt it has a wastegate.

mrploppy

Original Poster:

27 posts

100 months

Thursday 13th May 2021
quotequote all
Well, I can see the actuator. And it moves. Garage confirmed that it's moving but they suspect it's not moving enough.