So our Q5 throws up an EPC light when driven aggressively. I’m pretty sure that as it’s my partner’s car and driven in a very pedestrian matter that it’s the actuator for the turbo. I took the cover off tonight and it’s very sticky and after looking at camera footage when the car had been revved above 3500 rpm the mouse doesn’t go back in the house very easily, I put a boroscope into the turbo and it’s very clean which makes me think it’s the linkageseizing as it’s not being used. I was able to move it manually with a bit of force. 

The problem only occurs when it’s been on a long journey I.e. it’s had the turbo used, it idles fine and there is no loss of power, but the fact the actuator doesn’t return on idle makes me think it’s just a bit seized. I have VCDS scans and I’ve replaced the MAP sensor. I’m not a mechanic but I get the feeling that when pushed the actuator seizes on the linkage past the point it’s normally pushed. Any tips on what spray to use to remove carbon rust etc externally and the best high temp grease for afterwards. 

1 hour ago, Brian197626 said:

So our Q5 throws up an EPC light when driven aggressively. I’m pretty sure that as it’s my partner’s car and driven in a very pedestrian matter that it’s the actuator for the turbo. I took the cover off tonight and it’s very sticky and after looking at camera footage when the car had been revved above 3500 rpm the mouse doesn’t go back in the house very easily, I put a boroscope into the turbo and it’s very clean which makes me think it’s the linkageseizing as it’s not being used. I was able to move it manually with a bit of force. 

The problem only occurs when it’s been on a long journey I.e. it’s had the turbo used, it idles fine and there is no loss of power, but the fact the actuator doesn’t return on idle makes me think it’s just a bit seized. I have VCDS scans and I’ve replaced the MAP sensor. I’m not a mechanic but I get the feeling that when pushed the actuator seizes on the linkage past the point it’s normally pushed. Any tips on what spray to use to remove carbon rust etc externally and the best high temp grease for afterwards. 

Hi you say you replaced the MAP sensor? common practice on older engines is to replace the MAF sensor as well as the communication between the two is critical and if the information correlation between the two is not correct that will throw a light up, check the flow information for the MAF on your live data, had this on my car a couple of times and both times it was the MAF as it was not supplying the correct information therefore the ECU puts in a failsafe strategy that wont allow the turbo to boost.

Steve.

Hi Steve,

 

thanks for the reply believe it or not there is no MAF sensor on my car!!! Which I find unbelievable too. The car is away at the minute but I’ve looked for it a few times. 
 

I’ve got an RS5 and finding anything in that engine bay is a task, but the Q5 has a lot of room. One place I haven’t looked is under the air filter, but it seems a stretch. 

10 hours ago, Brian197626 said:

Hi Steve,

 

thanks for the reply believe it or not there is no MAF sensor on my car!!! Which I find unbelievable too. The car is away at the minute but I’ve looked for it a few times. 
 

I’ve got an RS5 and finding anything in that engine bay is a task, but the Q5 has a lot of room. One place I haven’t looked is under the air filter, but it seems a stretch. 

Hi your car does have a MAF sensor otherwise it wouldn't run very well yours is the DETA engine and the MAFF will be after the air filter box its a tube with a wiring plug in it, in the old days you could just replace the sensor but now they are a one piece affair.

Steve.

Steve. Genuinely there isn’t a MAF sensor after the air box… that’s  where I’d expect it to be too but there isn’t one there are no leads or connectors on the intake from air box to turbo.the collar is intact so there has never been a sensor, apparently it relies entirely on the MAP sensor, which is weird

18 hours ago, Brian197626 said:

Steve. Genuinely there isn’t a MAF sensor after the air box… that’s  where I’d expect it to be too but there isn’t one there are no leads or connectors on the intake from air box to turbo.the collar is intact so there has never been a sensor, apparently it relies entirely on the MAP sensor, which is weird

Hi I was assuming we were talking about a Diesel engine but your profile does not denominate but if it is diesel have a look on eBay there are over seven hundred listings for your model.

Steve.

Hi Steve, 

 

As it seems a you’re the only person that actually bothered. I’ve fixed it. After changing the MAP sensor (sorry I didn’t mention petrol), and looking at everything VCDS chucked up I finally thought that my other halves pedestrian driving might be at fault, so disconnected the waste gate sprayed the linkage with WD40 and and went about manually opening and closing the WG after doing this for a while, I reconnected the waste gate and recalibrated by turning the rod whilst watching the VCDS actual output to get the voltage to 3.633v. Then a bit of HT copper grease, and the fault hasn’t come back, so I’m guessing it was lack of use.

I got a clue because Audi Canada were sued in a class action lawsuit suit because of turbos failing, they said it was due to cars not being driven aggressively, the average cost was £3000, so I though I’d at least try.

Thanks for joining in I really do appreciate it, and I’ve posted a reply because usually when there’s a fix we’re all left hanging 

 

Thanks Brian
 

 

Edited February 2Feb 2 by Brian197626

34 minutes ago, Brian197626 said:

Hi Steve, 

 

As it seems a you’re the only person that actually bothered. I’ve fixed it. After changing the MAP sensor (sorry I didn’t mention petrol), and looking at everything VCDS chucked up I finally thought that my other halves pedestrian driving might be at fault, so disconnected the waste gate sprayed the linkage with WD40 and and went about manually opening and closing the WG after doing this for a while, I reconnected the waste gate and recalibrated by turning the rod whilst watching the VCDS actual output to get the voltage to 3.633v. Then a bit of HT copper grease, and the fault hasn’t come back, so I’m guessing it was lack of use.

I got a clue because Audi Canada were sued in a class action lawsuit suit because of turbos failing, they said it was due to cars not being driven aggressively, the average cost was £3000, so I though I’d at least try.

Thanks for joining in I really do appreciate it, and I’ve posted a reply because usually when there’s a fix we’re all left hanging 

 

Thanks Brian
 

 

Hi thank you for the reply we don't often get many of them which makes you a valued member, petrol driven cars are a different operating system therefore the mass airflow I believe is calculated by one of the sensors on the Cat so that would explain why my answers were diesel related as that's all I have ever owned for the last twenty years, morbid fear of excessive oil consumption I suppose, but well done on the proactive fix and for the sake of some time and two pence worth of chemicals its a good result.

Steve.