Intermittant partial power loss on 2.0 TDI 170

[jakerade]

I keep experiencing partial power loss on my car. Its like it loses 50+ Bhp in the middle of a journey for a short period of time and then returns to normal. Also feels like its running a bit rough and occasionally "coughts" at motorway speeds and also under acceleration.

The mobile tech has been out once after having engine management light on solidly for a day and the heater coil light flashing. He couldnt find any faults when he scanned the cars except ones relating to the hand brake which he cleared.

It recently had a DPF sensor replaced as well. Any thoughts from the techs out there? Sick to death of taking the car back and forwards to the dealer so want to be able to point them in the right direction.

Thanks

[Crasher]

If the coil light was flashing it must have stored a code, get someone else to read them.

[a8 tech]

sounds like passive regeneration also you need a fault code reader that can read uds protocol for 2008 onwards so vcds current release

post a code if possible or read dpf ash content and regen attempts/successful attempts

always ensure you have at least half a tank of fuel to regen the dpf


sudden loss of power can also be a sign the waste gate actuator sticking as this has become a common issue on the cr diesels or restriction in the egr

but as Crasher has mentioned scan with the current vcds beta version and post full fault code with ambient readings and ecu sw version plus advanced data for flash status so we can see if the recent dealer visit for the dpf sensor also incorporated sw update

[jakerade]

Thanks - I have it booked in for next wednesday.

The mobile tech was the dealers Mobile guy and had the full audi gear although he did say there were more indepth tests that could be done in the workshop.

[jakerade]

all the warning lights are back on today so perhaps that will help them diagnose it. At 50mph in sixth, foot to the floor and not a lot happens

[jakerade]

Car returned with from dealer with heater coil flashing constantly and engine management light permanently lit. Apparently another exhaust gas sensor needs changing as the first one burnt out the second?

Getting beyond a joke now......

[Crasher]

That is not good!

[jakerade]

if its getting that hot, what else will it ruin? turbo & DPF?

Just writing a little note to Audi UK..

Cheers

[Crasher]

There is a warning in the manual something along the lines of take car or the car will catch fire…

[jakerade]

umm - thats not good. Anyway the dealer principle and audi UK have just recieved an email. I didnt see anything in the manual other than take to a dealer as soon as possible.

[Crasher]

Sorry, the workshop manual about forced regeneration which is what I suspect they have been doing. I have seen the cat temp reach 850 degrees...:scared:

[jakerade]

do you think the DPF is at fault. I have had the Brand Director of the motor group on to me since sending the email 20 mins ago so have an opportunity to steer this in the correct direction!

Thanks

[Crasher]

Possibly, they do seem to be becoming a major headache.

[jakerade]

marvelous!

[jakerade]

Well they have had the car for almost a week now. Fair play to the dealer they said they want to test it to make sure problem solved for good. The dealer has also put a 4th year warranty on the car which i think is the decent thing to do considering the on going issues. I pointed out that if it has got hot enough to ruin sensors, what else is about to go wrong.

Audi UK, however, have been next to useless and on monday phoned up and said that a guesture of goodwill for all my hassle the dealer will fill the car up with fuel!!! Well that was like red rag to a bull as when they picked the car up i had just filled it up.... She also said that they didnt have to replace the headlights previously (Xenons with octopus wandering around inside it) and that was goodwill as well (well it was goodwill from the dealer as Audi UK refused to do it!).

Not impressed with Audi UK and am tempted to reinsert the lines (which i removed from my initial complaint) about being a loyal customer long before they started stealing BMW's customers, sponsoring philandering footballers and increasing the cost of camping at LeMans from £250/person to £1500/person last year when i next email them. (actually I probably wont but i am still thinking it!)

At the rate they are going, BMW is likely to steal one of their customers!

[jakerade]

unfortunately still having the same problem even though they have replaced the sensor. I have narrowed it down to 1-2 secs delay in throttle response and then the turbo starts to spool up. It did this between Thursday (when i got the car back) and saturday but then started working almost normally on saturday pm. As someone said on another thread, they seem to be treating the symptoms but not the cause.

Any advice? Eg look at EGR valve and DPF for blockages? Would there diagnostics not have shown this.

Thanks

[jakerade]

They are changing in the injectors. Not quite sure how that will help make the turbo spool up faster when the engine is already revving?

[jakerade]

Picked up the car yesterday running ok although still a little slow in my mind.

Today the coil light flashing and its going slow again so its going back!


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[jakerade]

Exhaust pressure sensor is showing a fault? That would be the third exhaust sensor. I believe today is the 27th day my car has been at the garage since mid May

[jakerade]

Day 29 - engine ECU on order

[J_B204]

I know this won't help but look on the bright side - by the time they've finished you have a completely new engine installed!

Feel for you - I really do!

[jakerade]

thanks - its all pretty depressing now. I cant see this making much difference but prepared to be proved wrong.

[jakerade]

boring.... day 31 and the ECU hasnt arrived yet.

[phatAvant]

Feel for you, but they should definately do better in making this right as its unacceptable to be going on this long.

[jakerade]

with the bank holiday coming up I cant see me getting it back this month....

[phatAvant]

with the bank holiday coming up I cant see me getting it back this month....

Get them to give you an extra special replacement vehicle, something nice ;)

[jakerade]

Just contemplating my next move.

[Crasher]

I always feel replacing the ECU is a move of desperation as ECU faults (especially ones that act like yours is doing) are in my experience extremely rare.

[jakerade]

Thanks Crasher, that is my worry as well. What would you do? The last technical bit of info I got was that it was "storing a fault for the exhaust pressure sensor". I suggested that they should have the DPF and EGR off for inspection if nothing else (not that i really know what i am talking about!)

[Crasher]

I think the DPF is blocked.

[jakerade]

thanks - would diagnosis tools actually show anything or is it a case of taking it out and having a look?

[Crasher]

It should show up in Measured Value blocks but I am sure they must know how to do this…

[phatAvant]

It should show up in Measured Value blocks but I am sure they must know how to do this…

You'd think but you can never say "they must know how to do this" when talking about a dealer.

[jakerade]

Apparently there was a "short" in the ECU. I havent got the car back yet so can't confirm whether this has fixed it

[Crasher]

Huge pinch of salt to be taken with this diagnosis.

[jakerade]

its due back thursday...

[a8 tech]

I have recently dealt with a similar issue and the fault code changed every time however they were linked by a reference voltage supply from the ecu and the fault was caused by the crank sender.

It took me 2 weeks (that's at home as well) to find the cause however it could be seen the crank signal was lost over the drivetrain causing lack of power and jolting (multitronic) but the faults related to short to positive across all the engine input senders but often without fault a fault code and no pattern, and only after the engine had reached normal operating temp and 1 hours driving.

I drove around for 1 week with the car connected to scope and vas and noticed the reference voltage drop to 3.5 volts and only by disconnecting the sensors one by one did I find the failure.

There was only one constant reading when the fault occurred which highlighted a signal issue and that was found in the fuel rail pressure which spiked to 90 bar above normal however this was a signal problem and not actually a correct pressure recording

Its highly unlikely the dpf is blocked and suspect either the wiring is shorting, defective sensor (but which one) or processing error within the ecu

I would not rule out an engine wiring loom issue or g28 signal braking down when hot

Sorry I have not replied earlier but I have been very busy

[Crasher]

It isn’t just me that brings their work home with them then? You are as sad as I am!

[a8 tech]

only way to do it these days, as I have all the gear at home its easier and don't suffer from "can you just look at this for me" lol

[jakerade]

Thanks guys

Mine was doing this from cold sometimes but sounds pretty familiar otherwise

[jakerade]

Its back, seems ok although it still does this thing where by the rev needle goes up slightly and then drops when you put your foot to the floor - is that normal in a manual TDI?

[J_B204]

Can't say I've noticed anything like that but then I don't put my foot to the floor very often!!!

[jakerade]

not convinced its fixed the problem but giving it ago over the weekend.

The needle jumps around almost as if its lose and you have gone over a huge bump. I dont reckon that can be right

[jakerade]

Problem doesnt appear to be solved to my mind.

To give an example;

When its running right, at about 50mph in 6th I can tickle the throttle and you feel an instance pickup response.

When its not running right, which can be 30 secs later, you can put your foot to the floor (even when going down hill) and there is very little danger of running into the car in front of you. Pretty much nothing happens.

Getting rather frustrated now....

[jakerade]

Still struggling with this. Its not a total power loss, just doesnt run right sometimes which is very frustrating. Been back to the dealer and "no fault found" . Perhaps i will chop it in for a beemer.....

[Crasher]

Perhaps i will chop it in for a beemer.....

Please don't do that, the thought makes me feel ill! Let’s start again, what are the symptoms of the problem you have as it stands now after a new ECU?

[jakerade]

The engine is normally very sweet and free rev'ing. When it plays up the engine note deepens and the throttle response is pretty numb.

Normally in say 5th gear at 50mph you can give it a bit of throttle at it will take off. When it plays up it will go but you are constantly adding more throttle. The car also seems to lose speed quicker.

The dealer has checked the dpf apparently. It had an exhaust pressure sensor but not a dpf sensor and apparently it is regenerating normally. I havent got any tools to check myself and there are only a limited number of independants out in east suffolk. I did wonder if the turbo actuator was playing up but have not had any fault lights since they changed the ECU.

Thanks!

[Crasher]

There are steps in the dealers diagnostic system Guided Fault Finding to work through this problem, not just reading fault codes as this is no guarantee of success. Are there any warning lights on now? What is needed now is a fault code read from someone independent to the VAG organisation, someone with a registered copy of VCDS would be ideal. You should have a CAHA code engine. Call your dealer and ask if TPI Transaction number 2020792/3 is applicable to your car and if it is, has it been carried out?

[jakerade]

Thanks

I took it in a couple of weeks ago and there were no fault codes stored. I havent had any warning lights since they changed the ECU in the summer. Its a 58 plate 2.0 CR 170. There is a new indie Norwich way so i could give him a try. What is that TPI for?

Many thanks again

Jake

[Crasher]

Workshop campaign 23D9 Transaction No.: 2020792/3

Replacing regulating flap, 2.0 ltr. TDI engine Release date: 24-Jun-2009

Notes

Repair instructions

Technical background

On Audi vehicles with 2.0 ltr. TDI engine manufactured within a specific period, it is possible that malfunctions can occur on the regulating flap (intake manifold flap motor -V157-). This can result in driveability problems and can cause the fault warning lamp for the engine management to light up.

Remedy

The regulating flap (intake manifold flap motor -V157-) must be replaced on the affected vehicles. A hydraulic fluid cooler must be retrofitted additionally on vehicles with criterion 01.

Customer notification

Customers do not need to be informed directly of this campaign. Please ensure that all affected vehicles are checked and repaired during a service visit. You should also inform your new and used car sales departments so that the vehicles affected can be checked and, if necessary, repaired immediately (and not just before sale).

Repair instructions

Notes

Technical background

On Audi vehicles with 2.0 ltr. TDI engine manufactured within a specific period, it is possible that malfunctions can occur on the regulating flap (intake manifold flap motor -V157-). This can result in driveability problems and can cause the fault warning lamp for the engine management to light up.

Check

If the vehicle is not already listed as repaired in the "vehicle-specific notes" (in Service Online or ELSA), check the Service Schedule for the entry '23D9 completed'. If the entry is not listed, carry out the required work in accordance with instructions.
After completing all required work, make the entry "23D9 completed" (including date and workshop stamp) in the first vacant box in the Service Record section of the Service Schedule or in the section for Workshop remarks.

[jakerade]

will give them a call tomorrow

Thanks!

[jakerade]

Hi Crasher

I checked and its not relevant unfortunately :(

[jakerade]

Frigging engine management light back on - trying a different dealer this time

edit

Its almost a year to the day the light first came on - perhaps its "Moffett's Ghost"

[MFGF]

Oh my! You are having an awful time with this car! I hope you have better luck with your new dealer!! Good luck!!

MF.

[jakerade]

Took it to Lowestoft Audi this time and they say its an exhaust pressure sensor (again....) but it was two hot to diagnose which one (only drove it 20 mins up the road at 50mph and it must of had 30 mins to cool..) so booked back in for next thursday/friday. Covered under extended warranty

Tempted to pay them to check the EGR / DPF?

[jakerade]

Fingers crossed that Lowestoft Audi have performed some magic. On the way home I saw 64MPG driving pretty gently in 50mph traffic. I have only ever seen 50MPG twice on a journey which involved a lot of free wheeling etc. I have reset the long term DIS (41.5MPG) and will see what happens. I did verify the MPG the other day and a tank of 530 miles was giving me 42MPG approx.

It now also pulls from about 1200RPM (not manically but you can tell its making an effort)

I asked them how much to check EGR (1.5hrs) or DPF (6hrs @ £95+VAT - you have to drop sub-frame) and decided that I would leave it at this stage. Not sure what they changed but I intend to find out!