Touareg 3.0 Tdi - running issues / power loss

[Etticus]

Hi

i just bought a 2007 3.0 V6 Tdi with 160,000 miles on it to use as a farm truck. It is a MK1 facelift model with a BKS engine.

Drove ok on test drive (tho on reflection is was maybe a bit down on power) and the only issue it has is a leaking injector seal (ticking/hissing noise) on one cylinder bank which I will repair.

Drove it home 10 miles fine and then when I next went to use it, it was down on power, wouldn’t Rev over 4,000 rpm /struggled to change gear. It felt like limp mode that you could get with a choked EGR like I’ve had on other diesels but no engine lights came on and it didn’t produce any codes when I put my OBD2 reader in it.

So I thought dirty fuel filter and changed the fuel filter, it was the dirtiest fuel filter I’ve ever seen, put some diesel clean in the tank as well and took it for a 20 mile drive. It drove faultlessly and I thought it was fine.

I took it out later that day and it was again down on power (wouldn’t rev/ change gear). I thought there must be more dirt in the fuel so I stuck it in a low gear and kept my foot to the floor to try and clear the issue and after a few miles it started to try and climb up the Revs and then the issue cleared and it was back to what I think it should be. Again no engine lights and no codes.

Next morning it was fine, drove about 20 miles and then when I next got in it the problem returned.

So I thought dirty filter again, checked that and this time it was clean. Took it out the next day and it was fine, then when I used it later on again it was down on power.

This seems to be a pattern now of running fine and then the next time you use it, it’s down on power. It has never lost power when I’ve been driving it. Never had any error codes or engine warning lights. It has once cleared itself when I’ve been driving it. After it being down on power one day it’s fine the next.

I have experience with Landrover diesels and I’m thinking something in the fuel tank or an issue with the fuel pumps in the tank as a LR can behave like this if the tank fuel lift pump is failing.

I got a workshop manual so my next plan is to open up the fuel tank and see if there is anything floating about in there that’s getting stuck in the filters in the bottom of the pumps and if not investigate the tank lift pumps to see if they are pumping enough fuel to the engine. I didn’t notice one time it was playing up that the fuel gauge was showing the tank as full when it was only 2/3 full. When it was fine the next time I used it the gauge returned to 2/3.

If I was getting error codes I would think it was going into limp mode but because I’m not I keep coming back to fuel starvation caused by a blockage somewhere or failing lift pumps.

I do intend to the get the vag com software to run a proper diagnostic as I’ve only got a OBD2 reader but as I’m not getting any engine warning lights I’m not sure if there would be any codes anyway.

Pretty confused about this so any help greatfully received.

[Etticus]

Been thinking about this a bit more after driving it this morning and it being fine after being down on power last night and fine yesterday morning.

It appears to never be down on power from a cold start and the only time it is is from a warm start albeit it doesn’t do it every time.

I don’t know enough about these engines but is it the case that the EGR valve is in a different position on a cold vs warm start?

Could it be that what’s happening is the EGR valve is sticking sometimes from a warm start?

Though the thing that’s confusing me is no engine management light or error codes so I keep coming back to fuel supply issues. Should EGR issues always produce an error code?

I do have EGR cleaner that you spray in the air intake so I might give that a try and see if that makes any difference.

is there a way you can check if the EGR valve is sticking or blocked without taking the EGR valve off the engine?

[Etticus]

Not getting any responses but a handy wee note for myself if no one bothers.

So this morning from a cold start car is fine.

Then go for a run with a warm start and the car is down on power as per.

So this afternoon decide to go for a long test drive. Cold when start and drives fine for 20 miles or so. Then it loses power. Drive for 5 miles or so and it goes back to normal and it’s fine for 10 miles till I get home. Put half a can of egr cleaner down the intake, plenty smoke out the exhaust.

Go for a run after and it’s down in power. Then it recovers and is back to normal in 5 miles or so, then it loses power after I thrash it up a few hills and then back to normal after a few miles. EGR cleaner obvs didn’t solve the issue but it the engine was running better.

No error codes or engine lights during all of this.

So I’m coming round to this problem being temperature related. When it heats up it loses power and when it cools down it returns to normal. The harder I drive it the sooner the fault returns and the gentler I drive it when it is faulting the sooner full power returns.

I had a look at an Audi forum someone had an issue with a 3.0 Tdi Q7 and a faulty fuel temperature sensor which was exaggerating the fuel temperature, causing the car to restrict torque output but not go into full limp mode. So I am wondering if this could be my issue. I am not going into full limp mode but I am down on power so can’t do more than say 60mph and you need to change gear manually to make progress.

Sensor appears to only be about £15 but I’m going to try and work out how to test it before I just chuck one on.

[gareth23]

I'm not going to be much help but I'd wait until you get VCDS, you might have fault codes logged even though the EML isnt on and I'm not sure if a generic code reader would show everything?

Plus you can start looking at sensor readings to compare when its ok an when its down on power - hopefully someone else can point you in the right direction as a start point.

[Crasher]

When you post the VCDS scan, include the VIN?

[Etticus]

So wee update.

Finally got round to getting vcds.

scanned the car and I get a P3348-009 electrical malfunction fault on the turbo actuator. I was not expecting this!

I had already checked the actuator when I first got the problem and it was moving freely and as I said no error codes on my OBD2 reader and no engine warning lights. That and the fact the fault appeared to be temperature dependent threw me completely and the filthy fuel filter at the start of this didn’t help either.

so cleared the faults and took the car for a run to try to get it to fault again while also logging some live data, revs, torque demanded, torque limited, MAF sensor and fuel temp.

So Fuel temp was fine 27ishC, MAF was down when faulting and torque was being limited but once the engine cleared itself it went to where I assume it should be.

So had a look at Ross tech website and as per the guidance checked the electrical connections and wiring for the actuator. Lo and behold the plug on the actuator was loose and the wee clip on it was broken. So skoosh of contact spray, cable tied the plug in.

Next two days drive without fault but it did fault again this afternoon albeit I admit I have been ragging it and turning it off and on a lot when it’s hot to try and get it to fault. When it did fault the fault did clear a lot sooner than it has done in the past and when active the engine wasn’t as gutless as it usually is. So clearly the bad connection in the plug was big part of the problem but we still have an issue.

So if it faults again my next plan is to open up the actuator housing and lubricate the gears in case this is why it is sticking when it is hot. I have found a thread in here by an Audi owner who had done this. He seemed to be able to get into it without taking the actuator off the car so I’m going to investigate to see if you do that on a Touareg.

Maybe you have a view crasher as you seem to know your way around these engines.

[Crasher]

Full car fault code scan and VIN please.

[Etticus]

I don’t know how to post a vcds scan but here is a photo of the error code screenshot taken with my phone.

Driving around a lot today. Faulted a couple of times but it’s not doing it as often, has a bit more boost than it had when I first noticed this problem and is clearing quicker since I sorted the plug on the actuator.

It appears the fault occurs when the car is started when warm or if you sit for a bit with the engine idling when it is warm. The error freeze frame seems to support this. Perhaps the actuator is sticking when it’s at whatever end of it’s travel it’s at when at low boost. I’ve also noticed that it’s keener to come back to full boost if you are coasting down a hill on no throttle than if the engine is under load.

So I’ve decided I’m going to go ahead and lubricate the gear wheels inside the actuator and the actuator arm linkage with some ptfe lubricant to see if that helps and put a bottle of wynns professional turbo cleaner in the fuel tank as well in case the sticking issue is inside the turbo itself.

If that doesn’t help then the next thing would be to test the actuator with the vcds, not sure yet if I need to take it off for this. If it fails then I suppose it could be new actuator time and so I’d be keen to know if you can program it with vcds or even use that as a guide to adjust the linkage arm properly. Prefer to do it myself instead of take it to a garage if I don’t have to.

35BEDDB5-DBC3-4B35-B79B-976196A2F906.jpg

[Crasher]

More than likely it will need the turbo off for a rebuild and the actuator bench set up after, Midland Turbo provide an excellent service.

[Etticus]

More than likely it will need the turbo off for a rebuild and the actuator bench set up after, Midland Turbo provide an excellent service.

If it ends up that way so be it but what’s making you think the turbo is knackered?

When it’s not misbehaving it pulls like a train and there’s no smoke.