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D2 - Engine Bay Everything under the bonnet |
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#1
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AAH rough "low" idle (warm engine)
Hi! Last year my engine started getting very rough on idle after a drive. Cold it idles just perfect @ 900-1000rpm, however when it gets warm it will be rough to the point I think it might stop but it doesn't. Since August last year I replaced the spark plugs and the rough idle went away. However now it's back and worse than ever. The car has done about 5k miles or less since plugs where replaced. In two weeks I'm heading off on a 1000km+ roadtrip in this car with 345000km on the clock. Anyone who had similar problems and have any suggestions?
At speed and above idle it's smooth as a baby's bottom, surprising to me having owned other cars at this age and mileage not doing that well. Over the last week I did a service on it replacing engine oil & filter, tranny oil & filter, fuel filter, coolant flushed and replaced with g12+ and cleaned and oiled my h&k panel filter. None of this did seemed to do it any favors.
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1996 2.8 Quattro |
#2
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Scan for fault codes followed with checking measuring blocks for misfire and lambda values should point you in right direction. Small air/ vacuum leak could be causing this, also IIRC idle stabilisation valve can get clogged up and sticky on AAH, cleaning with carb/intake cleaner or even WD40 usually helps. If you have VCDS you can also activate and exercise it when cleaning to make sure cleaner gets in all parts of it.
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Currently 8less 2011 Q7 S Line 3.0TDI, 2016 Tesla Model S 90D 8 history: 2006 A8 Sport 4.2TDI quattro SOLD, 1997 S8, reached end of life with gearbox failure |
#3
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Quote:
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1996 2.8 Quattro |
#4
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Sounds like a closed loop condition to me (when engine is warm enough to use all its sensors to run the engine).
Does AAH have a MAF? If so, unplug it and see if it idles better. If it does replace it. If it doesn't have a MAF, check lambda as Ainars said.
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Cheers Marty ____________________ Current: 2001 Audi S8 - Brilliant Black with Black interior, C5 RS6 rims (whenever I actually put them on...), Solar Sunroof, Tinted side and rear glass, RNS-D, Grom, Bose, clunky old phone in arm rest! 2002 Audi S8 - Project Replacement head coming arrived thanks to MJ Silver with Black interior. All features as the '01, with the 'S' mode auto shifter. Dodgey rear tint (need to find a way to get rid of that). Family: 2009 Volvo XC90 V8 R Design - has a louder more obnoxious exhaust than the S8, sounds great! Love this thing - Q7 was double the price, and certainly not double the car! Sold: 1997 Audi A4 - Hamilton's Club Sport, Achat Grey (will miss the old girl) |
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