Rough idle on s4

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Swifmcvay99

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Hi

Wonder if anyone can point me in the right direction,I have a 1999 s4 with 73k on the clock, car has full service history and is in very good condition,

When I start the car it idles rough, car runs perfectly fine, but when I'm at a stand still it idles rough,I took it to kwik fit for an Mot and service, and the technician found some faults and cleared them, and car idled perfect, but then car stood for a week and when I went to drive it again, same problem started,I thought it might be dirty fuel as it was on empty but I went and filled up with the good stuff.

Not sure if this will help, but when the car is idling I disconnect the maf sensor, and nothing changes, same idle.

Any advice would be very grateful, and before I take it in I was just hoping it would something I could check and replace first before I spent loads of money in it,

If there is anyone in the Surrey area that could take a look that would be awesome?

Thanks
 
Hi, I don't know as they didn't tell me they just said they cleared the faults,sorry can't be of more help
 
Hi

I found the codes if this helps

P1453 - Exhaust Gas Temp sensor 1 Open/short to B+
P1551 - Barometric pressure sensor circ short to B+
P0102 - Mass or Volume air flow Circ low Input
P1570 - engine control disabled/contr.module locked

I have googled these faults, but not entirely sure what I need to replace

I have got it read again, and the P1570 code doesnt appear anymore, this was fixed on the original diagnostics

Hope this helps?
 
They're all pretty self explanitory....

Bank 1's EGT sensor is faulty (common issue, best fix is to get replacement boards from s4sid as new audi ones dont seem to last)
Air flow meter is faulty
barometric pressure sensor is faulty (this might be the one in the ECU, which isnt easily repaired, however i wouldnt trust the data from a generic scanner)

You really need to get it scanned with VCDS, so you get the proper VAG/Audi fault codes out of it, the P1551 code doesnt seem to correlate properly with a VAG code.
 
Hi

Is this the guy?
 

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Hi

Ok so it turned out it was the MAF sensor, that was replaced and car doesn't idle like that anymore, only small issue I have now is, the car idles a little high now, maybe at about 1200RPM
any ideas?
 

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