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Mike, Technician
Category: Audi
Satisfied Customers: 39198
Experience:  Tech Expert
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audi s5 v8 Quattro engine hunts at low revs no faults deteckted

Customer Question

audi s5 v8 Quattro engine hunts at low revs no faults deteckted on audi scanner
Submitted: 3 years ago.
Category: Audi
Expert:  Mike replied 3 years ago.
Hello and Welcome..

My name is MIKE - Im happy to help / advise you .

Can you first please tell me some info..

Do you get any fault lights on when this happens?

What is the tachometer showing the actual revs to be at idle?

What is the mileage of the car?

What is its service / recent repair history ?

When was the last service done - time / date wise?

Other than a generic fault test as above - have any other tests / checks been done for this issue at all?

Rgds, MIKE....................................
Customer: replied 3 years ago.

no fault lights,6010 rpm at 90c,47000 miles , full history main and specialist , 4610two months ago, looked for leaks in vacuum pipes,
has been suggested that fault could be sticky throttle air flow butterfly ,

Expert:  Mike replied 3 years ago.
Hello again Anthony -

Thank you for your reply and info.

I note you say there are no fault codes -- but do you have any Live Data test results at all?

Do you have a print out of the diagnostic that was done?

Kind Rgds, MIKE.....................

Customer: replied 3 years ago.

dear mike ,no print out as there was nothing to print ,this scan was done by a friend of mine who is an Audi main dealer ,his meister mech suggested that it could a sticky butterfly which I believe is under the inlet manifold ,this problem only occurs on very light throttle pressure can you confirm his thoughts and tell me is this a big job to undertake myself .thanks Anthony to save time a phone call would by great ***********

Expert:  Mike replied 3 years ago.
Hello again Anthony -

Thank you for your reply - I missed you at the time , sorry about that. Im afraid we cannot do phone calls - hence you see the system has botted out your number - its for your protection.

The issue you have there Anthony is that even that should give you / produce a fault code.. Granted, sometimes they wont if its not too out of spec...but its hard to say it will therefore definately be that or not.. It could just as easily be a dirty ( inside ) TB -throttle body.. and in fact, I would indeed suspect that..and give that a good / thorough clean..using a spray cleaner for the job. You access the top and clean thoroughly with the spray - Open the accelerator flap ( air flap ) and fully clean the edges of the plate and where it shuts against the side of the chamber. Often the issue is that it sticks there on operation and causes what you have.

So I would suggest that and then see how it goes...

If it still has the same issue, I would suggest as we would do, is to use plug in equipment on Live Data testing - so that as you drive it, you can watch whats going on on screen to ID the fault..

Thats the way I would suggest on this one Anthony for sure.. Let me know how you get on.

If there is anything more you need or would like to discuss - by all means get back to me -

.>> Meantime ...........Please do click on the "OK/ Excellent ratings" for me as that's how Im credited for helping you - Thank you in advance for that...

You can and are most welcome to get back to me anytime you might need - clicking the OK ratings does not close you out at all..

Kind Rgds , MIKE.