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Audi A5 2.0 TFSI 2010 B8 feels like it has no turbo


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hi all


sorry if the post is in the wrong place. I bought an audi A5 2010 sportsback 2.0 tfsi recently from auction. After swapping the front end ( radiators bumper and whilst in there the timing chain gaskets). Once back to looking normal-ish i noticed that there is very little acceleration boost. Like the car doesnt have a turbo on it. I have VCDS and did a log of the pressure boost, but i have not got a clue as to interpret it. Before i start throwing money at parts ( PCV, Diverter, N75) if someone could have a look at the graphs ? i should mention that i took the Maf sensor out and the car felt a little better, revving at 6k rpm easier, even in neutral( although i dont know if 4k rmp is a limiter on these audi's and im messing with the engine)


Thank you



boost log.png


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Hi Lucian, removing the Maf sensor is indicative of the symptoms you present , these being Acceleration, Idling  lack of Throttle response.

The purpose of Mass Air Flow sensor is to measure the amount of Air reaching the engine . It contains two sensors ( wires ) these are symbiotic ( they work in conjunction with each other ) and send data to ECU Which does a calculation measuring the potential difference between the two , the outcome of which will  increase or decrease air flow. 

If you were to reinstate the Maf sensor , the injectors and airflow would work in synthesis as the ECU needs the Maf sensor information to do its calculation and thereby run the engine as it should and it would be able to calculate how much fuel to inject and how much air to allow for optimum performance response .

Removing this part of the equation means the ECU does not have any Values to work with in order for it to do its calculations

PS There is  a Limiter fitted . Jasonj

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Hi Jason


thanks for the quick reply. I have taken the logs before disconnecting the MAF Sensor. Would that point to a faulty MAF then?

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Hi Wayne, Re: MAF test ..  basic test .. ( For a vehicle in which the MAF has not been removed) 

1: Turn engine on 

2: Disconnect MAF sensor plug  "with the engine running"

3: If engine Stops Running  this means it  IS working correctly .

If the engine keeps running, that indicates it is NOT  working 

you can also test using Multimeter . if you have a Meter I will forward values of the volts range . Along with Resistance ohms

If you do replace MAF sensor you will have to drive the vehicle for 20 miles . This will allow the ECU to re calibrate the new values.

As you have been running this engine without MAF sensor fitted the ECU will compensate for this using defaults in its absence, but not very well . 

You can reset the MAF sensor by disconnecting the Battery for 10 minutes 

The New MAF sensor will have its own code that has to be codded in .Jasonj





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Thank for the quick reply. I just did a test now. With the engine running i plugged the maf out and there was no chNge

quick video attached.


i assume i can code the new one with VCDS? 



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Hi Lucian , Yes you can code it in 

But  there are two types of sensor analogue and digital from the part code on the sensor replace it with same part number so it corresponds to your system.

VCDS can detect both . Just make sure the one you are replacing is the same part number. Jaonj


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So I have managed to get to the bottom of the underboost issues. There was indeed an issue with the MAF as well so I have replaced that. The car felt better afterwards but massively underperforming. I have thought to check the Waste gate actuator and when moving it it felt moving freely. So I undertook the task to remove the turbo out entirely to check if any hidden issues and also to check if the turbo is ok. Well, after an insane amount of hours fighting rusty bolts, I have managed to get it out to find....that the turbo waste gate actuator it was off entirely so the wastegate was just flapping about doing noting. I have used an e clip to secure it in place as there was nothing there to hold it. Turbo and wastegate door is in good condition, the impeller and bearing is absolutely fine. The car now performs as it should, making really good boost.


However I now have an intermittent fault , "cam 1 actuator cylinder 1 intermittent" but by the looks of the harness wiring loom is understandable ( its busted and frail so will need changing. 


Have a look at the pics for everyone that has the same issue.




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Hi Lucian ,    Re:  "cam 1 actuator cylinder 1 intermittent" but by the looks of the harness wiring loom is understandable ( its busted and frail so will need changing. 

1: This is consistent with a compromised Wiring Loom , with the word intermittent .

2: Might also consider replacing Camshaft Position Sensor .

3: What is it like at,  Idle  RPM  ? Jasonj   PS great achievement 



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Hi Jason


At idle it feels like misfiring, not running smooth, which points to wiring loom or as you said camshaft position sensor. Will have a check on all pins with the probe.



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Hi Lucian, 

1: Once you fit the loom,  see how it is . 

2: Also Check Cam Adjustment Actuator on the Exhaust Camshaft . Thats the lower camshaft 

3: Make sure all the Timing Marks Line up .

4: Clean the mating surfaces ( Scotch brite type souring pad thing ) before re- assmbly

5: Check Torque settings and Flange Sequential order  ( llike star shape on wheels ) 

6: Respect , Big Time Jasonj

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