LCBL continues Audi A8

[SiC]

Do these even need a diesel cooler in the UK? Possible to bypass?

[DirtyDaily]

Do these even need a diesel cooler in the UK? Possible to bypass?

Probably not. Definitely possible to bypass. Worst comes worst I will however the there are pipes attached and it finishes the bottom and stuff so ideally want to maintain.

[Split_Pin]

I didn't even know it had one. The 75 has a diesel cooler fitted but it's behind the rear wheel and a lot easier to get to. Strange for a UK built car sold in tiny numbers in warmer climates.

[DirtyDaily]

So drive done yesterday, effectively driving from 3.30pm until 11pm with the purchasing of a jaguar XF in the middle. 

Audi did "well", XF was a lovely thing and drove back with no issues. 2015 car on 100k miles for £4k seems really decent value. When I did a car check on it it said that a bad trade in value would be £4.3k and the previous owner paid £8.7k in May 2023. I checked the rear subframe and the "rust" is so incredibly superficial. I will clean it up for her regardless as I know it's a failure point on these XFs.

Anyway back to the main attraction. A8 turbo I think has officially left the chat. Drove down fine but on the way back it was not for returning. Drove this morning to work and still no sign of a turbo lending a hand. Checked codes and it's the P0235 and P3348. The actuator is fubar. Luckily as I mentioned previously it drives alright without assistance, cruised back at 80mph without much bother except when encountering a large hill it was more like 70. Also with a good chunk of b road, hilly action on the drive it averaged 47mpg. All things considered a pleasant drive. I remember someone found a used turbo on an A6 at a pick n pull for £45. I am tempted to see if I can get that and solve this for pennies as I can obviously inspect the turbo for damage before I remove and worst case scenario that actuator is dead too but it keeps the car mobile whilst I am getting mine repaired. We shall see.

[Split_Pin]

It was Cort16 that found it at Upullit in Inverkeithing. Check the numbers but I think a B7 with the ASB engine is the same as well.

[grogee]

On 31/08/2024 at 09:01, Vantman said:

Shell V Power

 

[Dave_Q]

One suggestion if you are trying to do it on the cheap, I know there are lots of warnings about needing specialist kit to swap an actuator but 97.2% of refurbed units won't bother with this, some of them don't even balance them FFS.

If this was me I would be tempted to try just swapping the actuator in situ if it looks easier than taking the whole turbo out.

[Dave_Q]

This thread seems to say it should be possible by using VCDS to check the actuator reported position and adjusting the actuator bolts to the bracket to get it to match what the ECU is expecting. 

https://www.audi-sport.net/xf/threads/254866/

[DirtyDaily]

My initial assessment may have been hasty. Return leg home in the Audi and no turbo. I thought I'll quickly pull over see if the actuator is moving freely. It was. I then pulled the electrical plug that connects to the actuator and it just came off. I put it back on and drove and the turbo returned... There was no click when I put it on so I suspect someone has had the turbo disconnected at some point and broken the tab that holds it on. Could we just be looking at the plug working it's way loose every now and again?
Fingers crossed.
Also the diesel cooler arrived, £117. Still a lot for second bit of fuel line but oh well.
If the turbo is fixed from just securing the plug in then I will be very happy.

[Schaefft]

That would be like winning the jackpot, well done for finding this!

[Split_Pin]

Wish I'd checked that plug! I didn't even think to touch it.

[SiC]

Given the mileage and these turbos susceptibility to failure, it could potentially had a new turbo or actuator on at some point and never quite plugged in properly while the mechanic was in a rush to try getting the book hour times. Many don't know that you need to push the connector in when undoing the release tab. Pulling without doing the push first can snap the retaining clip on the plug off. 

[DirtyDaily]

Given the mileage and these turbos susceptibility to failure, it could potentially had a new turbo or actuator on at some point and never quite plugged in properly while the mechanic was in a rush to try getting the book hour times. Many don't know that you need to push the connector in when undoing the release tab. Pulling without doing the push first can snap the retaining clip on the plug off. 

I did think this. Not counting my chickens yet but going to put a cable tie on it to hold it in place and see how it goes. The problem was becoming quite common though so I think it'll be obvious if it's better

[DirtyDaily]

So a few days later and the diesel cooler has arrived and been fitted. Not a bad job and glad it's not marking it's territory now.
Checked the tyre pressures and they were all around the 24 to 28 psi range. These 20inches like close to 40psi so all those have been done and now rides a little smoother I think (placebo)
Turbo issue has been on once since I got a cable tie on it so suspect there is still an underlying issue with the actuator but it's not enough yet for me to make the car immobile for a week or two. I'll keep driving it and enjoying it and when there is a convenient time I'll take the turbo off for refurbing.
Long live the A8!

[IronStar]

If the connector was loose, would it be worth spraying some contact cleaner on both sides, just to make sure it’s getting a proper connection and not having intermittent problem because of the gunk buildup?

[DirtyDaily]

If the connector was loose, would it be worth spraying some contact cleaner on both sides, just to make sure it’s getting a proper connection and not having intermittent problem because of the gunk buildup?

Maybe worth a shot. I'll give it a go, no harm in trying.

[DirtyDaily]

Forgot piccies.
Guess which one is full of diesel...

[beko1987]

When the maf was dying in my 2.0hdi the symptoms were the same. Random turboing, either totally fine on cue or nothing, 2.0 n/a for you. 

It turned out to be electrical/replacement maf fixed it, I'd keep troubleshooting the wiring. If the turbo itself was knackered/out of spec you'd get a light on the dash and a code on something that modern? Tbh I'm surprised it doesn't ping up about the turbo being awol but mine didn't (did store a code but didn't put the light on) 

If it was something mechanical then the times it does work would highlight/show something? 

[DirtyDaily]

I get codes p0235 and p3348 which strongly suggest the actuator at fault. It also flashes the coil light when it tries to boost but doesn't. Turbo when boosting is great with little lag so no mechanical issues I can see.
Also on my drive to work today it never got up to temperature. I'll get a thermostat ordered.

[beko1987]

I guess it won't have any 'torque' to it and if it can't turn/spin it'll failsafe and error out. The fact that when it does work all is well is a promising sign! 

Good luck! 

[yes oui si]

Genuinely love that this is still in the fold and being carefully improved. 

[DirtyDaily]

Caught the actuator actively having a fit. No turbo on the drive home with multiple resets and then I opened the bonnet and found the actuator vibrating quite a lot. Unplug and plug back in etc yielded no results. I turned it off and worked the actuator back and forth a few times and it's working again...
Anyone hazard a guess? Could that be the gears in the actuator or the VNT being too stiff? Is it just bad?
May have to get it done sooner rather than later as I like it boosting.

ETA awesome video is awesome

[grogee]

18 minutes ago, DirtyDaily said:

Caught the actuator actively having a fit. No turbo on the drive home with multiple resets and then I opened the bonnet and found the actuator vibrating quite a lot. Unplug and plug back in etc yielded no results. I turned it off and worked the actuator back and forth a few times and it's working again...
Anyone hazard a guess? Could that be the gears in the actuator or the VNT being too stiff? Is it just bad?
May have to get it done sooner rather than later as I like it boosting.
 

 

ETA awesome video is awesome
 

 

Total guess but it seems like it's hunting for a position and cycling around it. Perhaps because there's too much play in mechanism (I'm assuming there's a motor and little gearbox with no doubt plastic gears). 

Then, after a set period of time, it shits itself and goes on strike as ECU decides 'desired position cannot be reached'. 

Pushing and fiddling moves stuff around enough that it's happy with the position so it plays ball until the next heat cycle and/or ignition cycle. 

[SiC]

There is mention elsewhere that some of these actuators break solder joints internally. I think it was on the position sensor too. 

[somewhatfoolish]

It does sound very unhappy; if there really are plastic gears inside it wouldn't surprise me if their life is limited due to heatsoak. Can it be removed and replaced without losing a reference point? Working the turbo doofer to make sure it's free to move(or to make it so) can't hurt if so.

[Split_Pin]

Aye that's got worse, this was it when it first started doing it, seemed fine:

 

 

[DirtyDaily]

Aye that's got worse, this was it when it first started doing it, seemed fine:
 
 

Its working again now. It seems that initial drop on ignition, is when it kicks in to limp mode or not because I find if the turbo is working it will work for the entirety of the drive. If it doesn't it won't.
Weirds.

[DirtyDaily]

Ever since the above the turbo has been playing ball so seems once you exercise the arm it gives it a few days of fault free action. I very strongly suspect (basically certain) it will return but may be worth while doing it every few days for the foreseeable if it does turn out to be the case. Maybe the silicon spray helped? #doubt
In other news I have purchased a new thermostat and also new gas struts for the bonnet.
Did I say new gas struts? I really am stingy. £17 each for OEM new or £8.83 for hopefully good used ones. If it stops it from falling on my head then happy days. If it doesn't I'll stop being dumb and buy new ones. I do like these kind of fixes though when they do work for pennies.

[SiC]

I've been buying the cheapest new struts (angrong usually the brand) on eBay and found them fine. Often on a eBay discount code too. If anything, sometimes they're too strong.

[SiC]

E.g. 

https://www.ebay.co.uk/itm/172296557762

£17 is still more than used admittedly but that is both.