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Audi A5 TFSI CARB 2008 - Manifold flap position fault - Fixed #

Posted by Luke Browne on February 1, 2016, 4:19 pm

Year of Manufacture *: 2008
Engine Size and Code *: CABD

Car came in with cam crank correlation codes and flap position fault. cam and crank code solved but flap position still logging.

The flaps open at the correct time (above 3000rpm) but fail to return as requested buy the vehicle. Thoughts were sticking flaps, however as soon as vacuum supply to the control plunger is removed (by disconnecting hose) the plunger returns.
It seems that the vehicle is not evacuating the vacuum supplied to the plunger but I see no way that it can? the control solenoid is brand new from TPS.

Have spoken to Auto logic and they are stumped and basically said throw a manifold at it which I can understand given rate of failure however the problem seems to be with the vacuum control, from what I can see but everything in the system 'appears' to be operational??

What am I missing??

Regards

Luke Browne

Re: Audi A5 TFSI - Manifold flap position fault

Posted by andyhyoung on February 1, 2016, 7:39 pm, in reply to "Audi A5 TFSI - Manifold flap position fault"
Andrew Young

I think the bit you are missing is when the plastic bushing wears/breaks on the flap pivots,the vac operated arm returns to zero position but the flaps don't.so the position sensor at the opposite end of the manifold to the actuator is seeing a a partially open flap position.I am sure it will be self explanatory when the manifold is removed.

Re: Audi A5 TFSI - Manifold flap position fault

Posted by Tim Watts on February 1, 2016, 8:16 pm, in reply to "Re: Audi A5 TFSI - Manifold flap position fault"
Tim Watts

I think Andrew is correct. Only done one with this issue. Removed manifold and linkages/bushes were in tatters.

Re: Audi A5 TFSI - Manifold flap position fault

Posted by luke browne on February 1, 2016, 8:47 pm, in reply to "Re: Audi A5 TFSI - Manifold flap position fault"
Luke Brown

Thanks for the replies, I get what you're saying however the vacuum plunger 'dosent' return to zero position that's the problem.
At idle the position sensor reads 0% as does the request then above 3000 rpm the plunger lifts, sensor reads 99.95% as does the request but when you let off the plunger remains in its current position as does the sensor percentage position and the request drops to 0% and the fault code returns?

I have removed the manifold since posting and see nothing conclusive? One of the metal separating plates which slide into the head is missing a rubber locating sleeve down one side, and the flap shaft has some sideways movement (approx 3-4 mm) and the valves are reasonably well caked in carbon as our the injector tips.

When you say bushings do you mean either side of the flaps themselves?

Thanks again for the replies keep them coming I can see this one turning my hair grey, customers already a fair few pennies In from the timing chain replacement

Regards

Luke Browne

Re: Audi A5 TFSI - Manifold flap position fault

Posted by Terry taylor on February 1, 2016, 9:29 pm, in reply to "Re: Audi A5 TFSI - Manifold flap position fault"
Terry Taylor

Hi Luke sorry not much help with your problem,what will you do with the injectors and the fact they are coked up looking at a asnu for future problems with injectors.thanks terry taylor

Re: Audi A5 TFSI - Manifold flap position fault

Posted by Tony Sefton on February 1, 2016, 10:36 pm, in reply to "Audi A5 TFSI - Manifold flap position fault"
Tony Sefton

Is it a single type control solenoid. ? If it is and the Vac pipes are the wrong way round then it will not dump the vac to atmosphere when switched off. They are usually marked up VAC and OUT.

Most likely too obvious a solution but it could explain your problem. ?

Re: Audi A5 TFSI - Manifold flap position fault

Posted by luke browne on February 1, 2016, 11:31 pm, in reply to "Re: Audi A5 TFSI - Manifold flap position fault"
Luke Brown

You may have hit the nail on the head Tony, I did check for 'in'+'out' but it wasn't stamped on the valve however the vehicle came to us from another garage who had already poked about and replaced a flap position sensor so could well have put pipes back wrong.

Thinking about it now it makes perfect sense that if the pipes were interchanged in this manner it would cause this exact fault! Will let you know tomorrow.

Sometimes you can't see the woods for the trees!

Regards

Luke Browne

Fixed #

Posted by Luke Browne on February 9, 2016, 11:38 pm, in reply to "Re: Audi A5 TFSI - Manifold flap position fault"
Edited by board administrator February 10, 2016, 1:12 pm

You were spot on tony

it seemed to have had damage to the hoses previously (heat damage) and had been replaced and incorrectly refitted on a couple of components.

Thanks for all you're inputs.

Regards

Luke Browne

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