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 Air leak or faulty MAF View next topic
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scott_w
Knows a Bit


Car: B5 RS4

Joined: 28 Nov 2012
Posts: 225

Location: East Lothian

PostPosted: Fri Feb 17, 2017 10:52 am  Reply with quoteBack to top

I've been trying to get to the bottom of this problem for a while but life is so busy it's taking longer than it should.

This car has had hanging revs while coming off the throttle in the lower gears, especially rolling up to traffic lights or in slow traffic in first or second gear - the revs almost hold bang on 1200 and don't really drop until you dip the clutch.

After researching a bit it seemed like clutch switch was a possibility, so I put a new one on for the sake of 15. But after replacing it, problem still exists.

I got the laptop out last weekend and scanned it - giving me two fault codes
17544 and 17546 - bank 1 and 2 - system too lean.

Upon more reading it appears to be an air leak or a faulty MAF, but what's the best way of find the leak or what are the most common places to get one?

I've logged a wide open throttle 3rd gear run for the MAF readings which I can post up when I get home later. I remember 360g/s being around the highest number logged, but will post the full log later.

Checked the idle and part throttle fuel trims while I was at it. Both  seemed a bit high if the desired number is 0%?

Idle was 9.9% and part throttle was 3.4%

I cleared the codes and have driven it about 50 more miles since, car seemed to drive a bit better to start with and then eventually got worse and the EML came back on, haven't rescanned it yet, but I presume both codes will be back.

I've had a quick look at all the vacuum hoses that I can see and tightened up any clips I can get access to. Their was a slight crack in one of the DV vac hoses, but right on the nipple so I don't think this was the problem, shortened the hose and the problem still exsists

Any advice would be much appreciated!
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Greig300
knowledgeable



Joined: 16 Aug 2014
Posts: 269


PostPosted: Fri Feb 17, 2017 2:12 pm Reply with quoteBack to top

Get yourself one of these:

http://m.ebay.co.uk/itm/AUDI-S4-R.../162359416371?txnId=1511236678006

Hook it up to a compressed air machine check for leaks. It will show instantly if you have any leaks and could prevent future turbo failure (over spin)

One of the best things I bought for my car and took me 15mins to find a number of leaks. One of my issues was unstable idle.
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Norrs2
Experienced


Car: B5 RS4, Ur quattro

Joined: 20 May 2008
Posts: 2285

Location: Perthshire

PostPosted: Fri Feb 17, 2017 4:53 pm Reply with quoteBack to top

Unplugg the MAF and take it for a drive to see if it improves.

_________________
2001 B5 RS4 Santorin Blue
MRC Custom Remap/Miltek Cat-back/Wagner Down Pipes /B7 Brakes/Loba Cams

88 Pearl White MB ur quattro

A3 Saloon quattro - New daily
A8 D3 3.0TDi quattro - moved on
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aidank1981
Experienced


Car: B5 S4
Power: 315
Torque: 375
Engine code: AGB

Joined: 16 Sep 2011
Posts: 2635

Location: shetland

PostPosted: Fri Feb 17, 2017 11:57 pm Reply with quoteBack to top

Greig300 wrote:
Get yourself one of these:

http://m.ebay.co.uk/itm/AUDI-S4-R.../162359416371?txnId=1511236678006

Hook it up to a compressed air machine check for leaks. It will show instantly if you have any leaks and could prevent future turbo failure (over spin)

One of the best things I bought for my car and took me 15mins to find a number of leaks. One of my issues was unstable idle.


good advise! there a pressure testing guide on here somewhere too!

_________________
http://audisrs.com/about28783.html
1999 T reg facelift 64k miles B6 wheels and brakes all round, KW variant 3's full turbo back 100 cell milltek non res AmD tuned aluminium mirrors.
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