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D3 - Engine Bay Everything under the bonnet |
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#1
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Knowlegeable D3 mechanic/garage needed?
afternoon,
I have this very weird issue with my car that I have taken to several reputable places to date and they haven't been in position to diagnose or provide a 'fix'... hence was wondering if this is something you could advise on and recommend someone who actually knows D3 A8's and especially 4.2TDI motor? Issue: cold - working fine; temp slightly up: starts stuttering/juddering at low revs nominal working temp.: all fine again to date I have replaced MAF's, air filters with genuine Audi, checked VCDS several times to no avail. MAF's were replaced due to similar symptoms I had on an A6 2.7T when it failed. something to note that A8 worked brilliantly when MAF's were off [Check Engine light came on but there were no juddering at any point and I have driven it for a week like that]. Thinking MAF's were erroneous I ordered new Denso parts (x2)- replaced them and the issue reappeared so to speak. I also ran several scans on VCDS w/o anything tangible that could point to the malfunction. and to add... I had driven the car around Europe like this [with 'an issue'] there were no problems having covered 4.5k miles apart from what I described earlier. I must say that I did 155mph on several occasions and having brushed off several 911's en route I don't think that car has a major problem... it must be something electrical that controls fuel-to-air mix etc. I'm not perfectionist by any means but this had been bugging me and I'd really appreciate need someone who understands these beasts to diagnose the fault hence the pleas for assistance ? any advise would be appreciated... thanks. Last edited by centurion; 24th June 2015 at 09:27 AM. |
#2
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hi have you tried a remap.
cheers trev |
#3
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Hmmm, during warmup the bypass on the fuel filter head will close. Maybe worth checking the seal on that or reading up on it.
What about EGR flow actual vs specified in VCDS? If you use the graphing feature and advanced measuring blocks do they correlate? EGR can use lambda probe after exhaust manifold or air mass to feedback it's flow. |
#4
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My Volvo had a similar issue and it turned out to be the engine temp sensor.
Normally, it would produce a fault code, but maybe it's only misreading slightly at certain temps? |
#5
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Apols if I've missed it, but can't see a location in your post for a recommendation?
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===SOLD===2002 Audi S8 D2 Final Edition (yes, really) in Avus Silver with purple extended leather===SOLD=== 2011 S5 Sportback in Phantom Black with black Super Sports leather, 9x20s, tech pack high, adaptive xenon plus, intelligent key, memory seats pack, sunroof, B&O, Audi Drive Select & quattro Sports Diff, DAB, parking system plus 2015 VW Golf GTI Performance Pack in Carbon Grey with black Vienna leather, tech pack (Discovery Pro nav & Dynaudio), DCC, factory towbar and retrofit RVC |
#6
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Yeah we need your location mate.
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2010 A8 SE Executive 4.2 FSI D4 2007 Mini Cooper S R56 2008 D3, gone, but not forgotten after 9 years and 90k. |
#7
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Quote:
I will do another run tomorrow night... in the meantime will you be in position to share with us what needs to be done [and How pls ]? |
#8
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I'm based in London and travelling is not an issue for a right mechanic .
Thanks |
#9
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I second other member views about temp sensor an EGR valve. Temp sensors are known to go on VAG cars and are cheap enough to do as preventative maintenance or part of troubleshooting, not sure how easy access is on 4.2TDI.
Another cheap thing to do not mentioned yet is fuel filter and making sure all the fuel line joints are sealed properly and not leaking. After that you are getting in more expensive territory like injectors, but needs more investigation, looking at measuring blocks etc on VCDS. Unfortunately cannot recommend any garage as I am not near London and I do pretty much all work on my cars myself anyway.
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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 |
#10
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Quote:
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2010 A8 SE Executive 4.2 FSI D4 2007 Mini Cooper S R56 2008 D3, gone, but not forgotten after 9 years and 90k. |
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