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.

hi have you tried a remap.

cheers trev

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.

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?

Apols if I've missed it, but can't see a location in your post for a recommendation?

Yeah we need your location mate.

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 :(]?

I'm based in London and travelling is not an issue for a right mechanic +++.

Thanks

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.

I concur about temp sensors. Not saying it may be your culprit, but they're cheap and easy enough to change, depending on location.

You ought to be able to log all the engine sensors in adv measuring blocks and start it logging just before you start her running, keep logging all the way through your issues until it stops doing it and then you can look back through the logg to see if there is any strange jumps in things like temp, maf, etc

Dellboy is spot on, you'll be able to spot any anomalies this way, one thing I sorely missed when I had my e39 after getting rid of my Passat.

There is few of us around London so depends where you live in regards to VCDS access. Where about exactly do you live.

About the garage.
I can't recommend more than enough guys from Audi VW specialist center in Harrow. A bunch of ex audi master technicians who got feed up with audi way of doing things and opened own business.
I'm confident that they are the best audi guys in London and surrounding areas. Best knowledge in all aspects, all the equipment and very very knowledgeable with A8s.
Just go and see Chris and tell him you've been recommended by Marcin from A8 forum, they will look after you. They are very busy tho so don't expect to turn up and see bunch of guys sitting in the garage and doing nothing waiting for the customers :ROFL:

cheers Marcin. Definitely one avenue i will explore.

i did another VCDS run today and no of 'faulty' items popped up... don't you love those cars :tuttut:!!!

i've cleared majority of those which were related to low voltage etc. [not sure why as car starts okay and battery is relatively new, less than 3 years old original Audi stock] but something that caught my attention was the following,

Address 11: Engine II Labels: Redir Fail!
Control Module Part Number: 4E1 910 409 A HW: 4E1 907 409
Component and/or Version: 4.2L V8TDI A000AGSª0070
Software Coding: 0011773
Work Shop Code: WSC 00097 210 80549
VCID: 224B0C03FD3A2A0EA27-8077
2 Faults Found:

008600 - Oxygen (Lambda) Sensor B2 S1
P2198 - 002 - Signal too High (Rich) - Intermittent
Freeze Frame:
Fault Status: 00110010
Fault Priority: 0
Fault Frequency: 31
Reset counter: 255
Time Indication: 0
Date: 2015.06.19
Time: 03:32:18

Freeze Frame:
RPM: 1071 /min
Torque: 3.9 Nm
Speed: 56.6 km/h
Duty Cycle: 0.4 %
(no units): 16.2
(no units): 1.0
(no units): 16.0

012376 - Exhaust Gas Recirculation System 2
P3058 - 000 - Insufficient Flow Detected - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 0
Fault Frequency: 4
Reset counter: 255
Time Indication: 0
Date: 2015.06.24
Time: 03:59:14

Freeze Frame:
RPM: 1806 /min
Torque: 171.6 Nm
Voltage: 13.07 V
Voltage: 2.68 V
Duty Cycle: 50.9 %
Duty Cycle: 39.1 %
Lambda: -6.5 %



i guess that is in line with earlier comments by snapdragon... i deleted all erorrs and will do another run later on tonight but would like to know if anyone an point out what to check/measure and log in VCDS related to EGR/lambda's etc?

Much appreciated.


ps. how easy or difficult is it to change lambda sensors?

I think it would be prudent to investigate the problems with the egr before digging to deep into other areas.

it may well be full of soot and need cleaning out

I had sticking/malfunctining EGR valve on 2.5TDI, I did not change it for a long time as access was not the best. In the meantime I was getting by exercising it with VCDS. It was sticking but if gave it a good exercise it was working OK for while. With engine running in iddle if you go to Basic Settings on VCDS and cycle through the channels until you see EGR duty cycle and airflow leave it for a while as it will be opening and closing the valve, you will also see airflow values with valve open and closed and compare them to specs.

On vcds there should be a specified and actual maf readings, on idle these should tally up together if reading correctly and egr is doing its thing, also take it for a run and see how they follow each other, usually there is a little lag on actual from specified as it catches up but it shouldn't be miles off, and should follow roughly the same curve, you may find like a lot of us though that there isn't a label file for your engine making logging a pain in the butt because you first have to find all the correct channels.

I recently had problems with no label files for my engine but the work around was renaming the r8 files.

In your case there is german lbl files so either you can read german and your laughing or go through these two files and google translate it then save into your label folders and you should be good to go

Thanks dell your a star, I did look into it and tried a label file from another 3.0tdi engined car and renamed it to coincide with the A8 file but to no avail :(

I certainly can't read German so it'll be google translate then :lol: +++

They are for the 4.2 BVN engine, but if thats not what your looking for google german vcds in stall it and navigate to the folder with the label files to find the ones you need

Once I opened the file I realised that :ROFL: i'v got the label file for 3.0tdi now, well i'v got the raw data I just need to put it into a label file, are you sure the files you posted are for the engine ecu measuring blocks? Going from what was written in the file there is a 3rd file needed, also it didn't have what I'd expect to see regarding data, it looking like mainly coding info?

Thats weird you are correct there should be 057-910-409-BVN3.LBL as well as the too that I posted but also like you said its still missing all the critical info and appears to only have the adaptation and coding info

Mine is using this...059-907-401-ASB.clb
It came with VCDS Version: 15.5.0.0 (x64)
I attached it

cheers guys.

as for what to monitor and report on, do you have any hints which group [from 001...019 under Engine or Engine ii] I should select and I will provide/post relevant info here? Much appreciated.

hiya,

I was wondering if you had chance to look at my last post and if you could give us your valuable feedback? much appreciated.

The fact that you say when you disconnected the air mass meters it ran well without any faulting says a lot .
When you dis connect an air mass other sensor will go off line also because they need the reference from the air mass .
Egrs will go offline and i would say swirl flaps will go off as well , you need to check that the swirls do there sweep , you have egr codes but sometimes egr low flow codes are caused by swirls not working .
If you get a situation where one egr or one swirl is working out of phase you will get a un balance between the banks .
I think the lamda code is a consequence of another fault ....its reporting a rich situation

Under data blocks check each air mass kg / h to see if they are balanced , thinking about it if one air mass is off this will affect egr and swirls on that bank
You could try putting blanking plates over the egrs to stop gas flow , you will get egrs low flow codes as a consequence but that's not a worry for the diagnostic principle .
It could be swirls or egrs sticking in the warm up phase and then when it gets fully up to temp it frees up again , under actuators do tests on swirls and egrs to see if the sweep is smooth and voltage range hits high and low desired readings

hi Lee,

I did spend some time last night on it going through some of your feedback with a view to take this [practically] into perspective... I noticed during several tests under Engine and Engine II - Measuring blocks that duty cycle isn't aligned on three fields [don't know what that actually means and why did it display on 3 x blocks in VCDS but two of the values were in line while another had +/-5... somewhat off the other two].

to add... I also did quick readiness test under OBD -> MAF and those values were originally somewhat off while the car was cold. As the temperature was approaching nominal one those were slowly coming together and settled around 5.3 [something]. Again, i don't really know what that means and what's the underlying cause of those misaligned readings but it seems that something isn't quite right... and i did several output tests too on the Engine and Engine II which didn't help much with the judder i have.

any suggestions or other tests i could do? I'd be more than happy to provide you with logs if you could specify what needs to be captured [and How :Confused:]?

Many thanks.

Without seeing some of the readings live it's difficult , some of the duty cycles being off could be down to different readings from air mass meters , at this point I would blank off both egrs valves with plates then see if the readings come more inline .
If the air mass readings come more inline sort of proves that one of the egrs is bleeding over , if air mass readings where still off you could try swapping air mass meters from bank to bank to see if a low reading transfers .
Have you looked at the turbo wastegate controllers to see if they both do a good sweep.

something I wanted to do over the weekend is to clean EGR's + manifold but w/o much luck... whether i'm plain d..t or unable to do one bit I got stuck on was EGR's. I unbolted 3 x main screws as well as 4/5 x for black cap with electrical connectors but was unable to move one or take out. Now I've done it several times on my previous 2.0 TDI w/o issues but this had proven a quite a bit of a challenge :(.

Has anyone got any hints on How to :Confused:? Ta.

I did replace both EGR's and both MAFs however the issue is still there!?

I did several readings on the car over the last week but there is absolutely nothing obvious that springs to my mind. I may need to seek professional assistance on this matter as it is driving me n..s :Confused:.

for my ref... apart from EGR+MAF are there any other components that could affect air to fuel mix, e.g. temp sensor? NOTE: I noticed that my 4.2 TDI takes fair bit of time (7-10min) to warm up compared for example to BMW 530d I had in the past. Is that 'normal'?

I have the 4.2 tdi mine takes 10 mins or so to get up to temp , just looking back over the posts , you say they car behaves with the air masses disconnected , this tells me it's not air ingress to the fuel or the bypass circuit re circulating any air in the fuel .

The temp sensor could cause this like others have said , it's cheap enough to do to rule out , the fault code for rich mixture .....I would say the lamdas are working and reporting the exhaust condition .

Now what would make a rich condition in a diesel ..... so rich is either to much fuel delivered or not enough air , or that the egrs are not flowing the gases which your codes were reporting and the lamda code was backing this up .... egr flow makes rich condition, egr no flow makes a lean condition .

You know back there were I said blank the egrs that's what you need to do now or just diss connect them so they cannot work , if one bank is getting flow and the other bank is not it will
Cause an imbalance between the banks

I'm not getting at you here more generalising , I see this everyday at work folk fitting parts off the back of fault codes or ' guess a part ' they will spend hundreds on parts and not fix it then come to us an moan at the £52 an hour we charge but I will fix it .... just a vac pipe split or summat daft

Customer .....£52 for a split pipe !!!!
Me " well you have spent hundreds and not fixed it so £52 is a bargain "

Yadder , yadder

Back to the plot .... blank or diss connect the egrs then see how it goes , one bit at a time .... carry out tests ......rule out ...... move to next test

cheers Lee... will you be in position to advise where the temp. sensor is and/or is this something that can be DIYed [easily]?

Ta

Im not sure , you can go into the tech dump sections on here and find it , normally two pin connector and its held in by like a fork type clip

The one for the 3.0tdi is in a coolant pipe at the back on the left (drivers) cylinder bank.

Just for reference, you never know it might be in the same place.

thanks.

Before I place an order for coolant temp. sensor any advise on which one to go for [of the 3 x options on MA site]?

http://www.mister-auto.co.uk/en/engi...9621_g830.html

I would get a dealer one to be honest , you know it will be right and the correct temp range and so on

Intrigued that they are only the 2-pin design whereas D2 (and I though most of the VAG range) used the 4-pin model which is (now) green.
http://images15.fotki.com/v260/photo...TSG_540-vi.jpg

yeah... I checked with a dealer and they have them in stock [~40 quid].

i'll collect it on Fri and give it a go over the weekend... or my info, how easy/difficult is it to install one :Confused:?