John C5

If the vanes are a bit sticky the turbo might be over boosting which would use more fuel and would be more noisy especially around the airbox. I used Archoil turbo cleaner in the fuel tank when I serviced it. Another job I found beneficial and low cost was removing the inlet manifold and cleaning the swirl flaps and EGR which tend to clog up. I also fitted a new diaphragm to activate the swirl flaps (which was about £25) while I had it stripped down. My inlet sat at -0.7 degrees after I changed the timing belt and set it to audi spec. The exhaust sat at 0.6l/h and it idled smoothly and ran great so I left it at that. It had been inlet +4 degrees and exhaust 0.8l/h before I changed the belt and had a lumpy idle until fully warmed up. Good luck, sounds as if you are getting there with it anyway, cheers John.

Thanks Ollie, I found that mine averaged between 40 and 50 mpg depending on how it was driven. The cruise control always seemed to get less mpg and my Allroad does the same. My son has the A4 now and he's only getting 35mpg but he'll be using  more of the 170bhp than I did 🤨

Hi Ollie, has your adjustment sorted your power issue. I take it you have no engine management light or fault codes? 

Indeed Stevie, first car was a mk1 Escort, then a succession of Minis before mk3, 4 and 5 Cortinas. Glory Days. No ECU but automatic (sometimes) choke 🤨 Still have an airflow meter and vacuum gauges but mainly use them on my bikes, cheers, John

Hi Steve, apologies, I should have just said throttle body. Sounds like you, like me, miss the good old days of points, distributors and topping up the oil in your SU carbs 🙈. I love working on my old Audi 80s and leaving the laptop in the toolbox, kind regards John.

45 minutes ago, Stevey Y said:

The trouble is there is so much information on line as to what the cause of your problem could be, all good but never definitive without codes being read it could be Anything, oxygen sensor, implausible correlation information between the MAP and MAF sensors, sticky turbo vanes, EGR bypass valve stuck, faulty injector, some faults can be in a chain where one sensor goes down and and the others get a default setting from the ECU to get you home [Limp Mode] all ECU software regardless of manufacturer will have a defence strategy built in to it, the idea is that you get home without destroying the engine I.E. it runs everything on the minimum range until the offending part is cleaned/replaced.

Had the once with one of my neighbours cars, he had recently changed the starter motor, fair effort, but some how he bent one of the pins on the oil temperature sensor no EML but when I was checking the fault codes for him it flagged up that the oil temp was 180 degrees this was of course impossible so the ECU had set a default so rather than the engine temperature being assessed from the oil and water sensor it was just relying on the cylinder head temperature sensor to tell the ECU what was going on real time, we changed the oil temperature sensor cleared the code and normality returned.

Agreed Stevey, it could be anything but I recently had similar symptoms on my A4 and no EML either. Read codes on Vag Com which showed two intermittent faults, "insufficient flow for regeneration" and "intake valve motor implausible signal" from memory. I took the anti shudder valve off and opened it up, electrical  components were full of oil, cleaned it up and refitted it. No more problem. 20 minute job requiring minimal tools or mechanical know how, no cost, although I have now replaced the valve as a worn out seal had obviously caused the issue. Turbo vanes sticking as you say can cause boost problems but not necessarily throw up any specific codes, a good fuel cleaner can sometimes sort this without having to strip it down. Just a couple of low tech, low cost suggestions, not a remote diagnosis 👍

The glow plug light flashes to show that there is currently a fault with your car, not necessarily glow plug  related. I agree you should get the fault codes read to give you an idea of what the issue might be. A common issue that causes this is oil getting in to the electrics on the anti shudder valve which can restrict flow through intake and EGR. DPF has it's own light so probably not that. Might be as simple as needing  a good fuel cleaner run through the system.

Hi Ollie, I wouldn't worry too much about it. I have a 2008 a4 with the BRD 2.0tdi engine with 230,000miles. It had the injectors replaced by Audi under warranty after they failed and also has had a new tandem pump. I noticed at the last few services that the fuel filter had fuel as you described. The only issues that I had with the car was a bit of a lumpy idle if not fully warmed up with a bit of smoke. This disappeared when it was up to temperature. I have just done a full service on it including belts as Vag Com was showing the inlet cam was 4 degrees advanced. All adjusted correctly now and rough idle and smoke are gone and car running great. I will check the fuel filter at the next service . FYI when the tandem pump needed replaced it caused oil to leak back to the fuel tank and car was very smoky. The tank and fuel line were all cleaned out when the new pump was fitted. Hope this is of help or at least puts your mind at ease. Probably quite common and just isn't noticed as most people don't pour out the contents of the old filter.

Hello, I am new to your Forum (and Forums in general). I own several old but capable Audis. A red 1992 B4 80 Coupe 2.0e, a blue 1994 B4 80 Cabriolet 2.6, a black 2003 C5 A6 Allroad 2.7t and a black 2008 B7 A4 Avant 2.0tdi black edition. All are in regular use with the allroad and the avant both well over 200,000 miles and still going strong. 

I do all my own maintenance and although the allroad is great winter transport I am currently making it better. It's now wearing Q5 alloys with 235/65/17 Dunlop Winter tyres. I raised it 10mm using Vag Com and fitted 25mm spacers to clear the bigger tyres and have now got a 30mm lift kit which I will fit as soon as I get the chance.

I have scanned through the Forum so far and it appears to be an informative and friendly club catering for a variety of vehicles and owners, cheers, John