Audi a4 1.9TDI Overboosting and goes into limp mode around 70MPH

alsiet2011

Hi,

I'm new to the forum and hope that I've come to the right place.

The problem is that she overboosts around 70MPH and goes into limp mode. It only happens at this speed which I find odd. I've researched this and some say that the MAF sensor could need replacing or cleaning but I don't have tools to get it out and my mechanic assures me it's not the MAF sensor.

The computer throws the error - 17965 - Charge Pressure Control: Positive Deviation.

So far the mechanic (not an audi dealer) has replaced 2 vacuum hoses that had cracks in them which didn't solve the problem. The next step is replacing some sort of valve but I can't remember the exact name of it. If that doesn't work the mechanic says next step is to change the ECU which from my research looks damn expensive

I'm just wondering does anyone else have a similar problem and would know why is it only 70MPH + that this issue occurs, no matter what revs are on the clock.

This problem has occured very seldom in the last 2 years but only recently is much more persistent. For the last 2 years I've driven the car very easy which I thought would help me prolong it's life (because it has high mileage) but apparently from what I've read, the vanes in the turbo can get stuck. If its stuck in the open position this could cause the issue. The last year or so I only do about 4 miles a day because my work is very close so was wondering might this have sped up the issue because its not getting driven enough and the turbo vanes may be getting dirty. I do however make sure shes fully heated up before I kill the engine each morning.

It looks like parts of my research contradicts what I'm being told by my mechanic (who is reputable) so I'm wondering would it be worth my while getting the MAF looked at / turbo dismantled and seeing if there's a problem with the vanes before I replace the ECU? How much of this can I do myself I wonder,. provided I have the correct tools?

I don't really have much $$$ to be putting into this unfortunetely so would appreciate any helpful work arounds / cheap jobs that any one could throw my way.

Thanks for reading and sorry for the long post. I just wanted to give all info available.

Thanks

My car details are the following:

Audi A4 2002 1.9 TDI
194,000 miles
Company car for 155,000 of those miles on UK roads.
Very well maintained and serviced (just fully serviced last week actually)

George Dalton

I would be surprised if it was the ECU.

From what you are describing where the problem has gotten steadily worse over time it sounds like the turbo is likely to be the cause. Impossible to diagnose accurately over the internet though.

alsiet2011

George Dalton wrote: »

I would be surprised if it was the ECU.

From what you are describing where the problem has gotten steadily worse over time it sounds like the turbo is likely to be the cause. Impossible to diagnose accurately over the internet though.

Ah dammit, thats what I didn't wana hear . My thinking was that if it was the turbo it wouldnt be fixed after an engine restart. Since rebooting the engine seems to fix it until it happens again would this not suggest that it's electrical?

I can't see myself getting a new ECU for it anyway. The cars hardly worth that much to be putting that kinda coinage on it.

Considering a 1.6 2006 A4 petrol atm. :P any thoughts on that?

Mech1

check that the waste gate control rod is moving freely, had one before that had siezed and wasnt operating just some wd40 and a good wiggle sorted it out.

alsiet2011

Mech1 wrote: »

check that the waste gate control rod is moving freely, had one before that had siezed and wasnt operating just some wd40 and a good wiggle sorted it out.

Interesting ! Is this something I can do myself with a torch and a long arm? What would the waste gate look like? I assume its a component of the turbo unit? If I wiggle it, how much normal resistance is expected? as in, would I be able to tell if it wasn't funtioning correctly or do I need a trained mechanic to look?

Thanks for all the responses already guys! Really appreciated.

pred racer

George Dalton wrote: »

I would be surprised if it was the ECU.

From what you are describing where the problem has gotten steadily worse over time it sounds like the turbo is likely to be the cause. Impossible to diagnose accurately over the internet though.

Does this model have the variable vane turbo?
A friend of mine had a similar problem on an older golf Tdi, a clean of the contacts on several relays, turbo vanes, maf and throttle body(i think) cured it.
Not sure which one was to blame, but the mechanic reckoned it was the turbo vanes adjusting incorrectly.
Sorry I cant be more specific it was a few years ago.

Greyfoot

alsiet2011 wrote: »

Interesting ! Is this something I can do myself with a torch and a long arm? What would the waste gate look like? I assume its a component of the turbo unit? If I wiggle it, how much normal resistance is expected? as in, would I be able to tell if it wasn't funtioning correctly or do I need a trained mechanic to look?

Thanks for all the responses already guys! Really appreciated.

There is a funny looking cylinder shape thingy on the turbo, that is your actuator, a hose connected on top. The rod that connect this yoke to the wastegate is the one you looking for.

Example:

alsiet2011

pred racer wrote: »

Does this model have the variable vane turbo?
A friend of mine had a similar problem on an older golf Tdi, a clean of the contacts on several relays, turbo vanes, maf and throttle body(i think) cured it.
Not sure which one was to blame, but the mechanic reckoned it was the turbo vanes adjusting incorrectly.
Sorry I cant be more specific it was a few years ago.

dammit i dont know is it variable vane turbo. is there any easy way for me to check>

yeah the list you made there if possiblitlies sound good. i think the N75 valve is the one on order but ill get him to check the vanes deffo when installing that.

any brain waves about why it only happens at a certain speed though? like, it has nothing to do with the RPM seemingly. Speed = air flow right? thats the only common denominator i can think of. i mentioned to him to check the MAF but the mechanic assures me its nothing to do wit it

George Dalton

It is a variable vane turbo, as such it doesn't have a wastegate.

alsiet2011

George Dalton wrote: »

It is a variable vane turbo, as such it doesn't have a wastegate.

thanks for all the help guys. ill post the results of the mechanic when i know more.

if anyone has any other input im always open to suggestions

galwaytt

George Dalton wrote: »

It is a variable vane turbo, as such it doesn't have a wastegate.

...do they have some sort of dumpvalve, though ? (like the 1.8t petrol ones ?) They (being cheap plastic) go awol after enough miles, so does the diesel not have something similar ?? (just wondering)

alsiet2011

galwaytt wrote: »

...do they have some sort of dumpvalve, though ? (like the 1.8t petrol ones ?) They (being cheap plastic) go awol after enough miles, so does the diesel not have something similar ?? (just wondering)

good question but i have no idea myself. i dont ever hear the kinda dumpvalve noise that i would be expecting (if they all sound like the ones boy racers have)

any mechanics out there wana chim in? shes a 1.9 tdi a4 2002 w/ 194K miles

George Dalton

No dump valve on a diesel.

MrFrisp

To be honest,the Limp Mode thing is a big problem in general..

I have had the same problem for about 2 years,and no closer to a permenant fix for it. There is just so many things it "could be",and so many things that "it's not".

If it's going to be of any help,,there is plenty reading out there about it..

http://wiki.ross-tech.com/wiki/index.php/17965/P1557/005463

http://forums.tdiclub.com/showthread.php?t=343934

http://forums.tdiclub.com/showpost.php?p=2602928&postcount=48

http://forums.tdiclub.com/showthread.php?t=179589


Most would point to a Turbo problem that can be cured in the short term with a good cleaning.

Hope some of those links help.





.

alsiet2011

SexyGuy wrote: »

To be honest,the Limp Mode thing is a big problem in general..

I have had the same problem for about 2 years,and no closer to a permenant fix for it. There is just so many things it "could be",and so many things that "it's not".

If it's going to be of any help,,there is plenty reading out there about it..

http://wiki.ross-tech.com/wiki/index.php/17965/P1557/005463

http://forums.tdiclub.com/showthread.php?t=343934

http://forums.tdiclub.com/showpost.php?p=2602928&postcount=48

http://forums.tdiclub.com/showthread.php?t=179589


Most would point to a Turbo problem that can be cured in the short term with a good cleaning.

Hope some of those links help.





.

thanks man, appreciated. can i ask, did you ever get ur turbo cleaned and did it help? its getting an N75 valve next week now (part still on back order) so if that doesnt solve it i think ill cut my loses. i cud be pumping money into this and the cars hardly worth much anyway at this stage of its life.

cleaning the turbo was somethin i was thinkin of but is that really expensive? talkin a good few hours labour surely

George Dalton

How about paying somebody who can actually diagnose the car properly instead of "pumping money into it" by fitting parts on a trial and error basis?

MrFrisp

Well,,as George says there..It would be helpful to get a proper diagnosis done first..It could save a fair amount of time,and money.

Yes,I had the Turbo cleaned once,using the oven cleaner method. If your any way handy at doing things,you could do it yourself,,but only if your confident about it,and you know your way around the engine.

Sadly though,,as you may read,,that method doesn't cure it 100% either,,as the problem tends to return after a few months.

To be very honest,,I'm not sure anyone has ever cured the Limp Mode problem 100% without actually having to replace the Turbo itself.
As I said before,there is just so many things that can cause it...It can be a nightmare to find,and cure.




.

alsiet2011

George Dalton wrote: »

How about paying somebody who can actually diagnose the car properly instead of "pumping money into it" by fitting parts on a trial and error basis?

yeah i am. its in the mechanics hands. by pumping money in it i meant, replacing x, y, and z (being the correct steps according to mechanic).

what i mean is i dont wana be continuously replacing bits and bobs until the correct component is identified. the cars not worth much so im reluctant to spend much on this. thats why i was hoping for any input from users that have experienced this type of issue. instead of the mechanic swapping out parts according to his VagCom I was hoping that someone may identify the exact cause so i could just focus on one area.

thanks for all the help so far though.

EDIT - The car has been with mechanic. Engine fault code is Charge Pressure control deviation. The computer gives a whole host of possible solutions which is no good because i dont wana replace loads of things that may not be the issue

alsiet2011

SexyGuy wrote: »

Well,,as George says there..It would be helpful to get a proper diagnosis done first..It could save a fair amount of time,and money.

Yes,I had the Turbo cleaned once,using the oven cleaner method. If your any way handy at doing things,you could do it yourself,,but only if your confident about it,and you know your way around the engine.

Sadly though,,as you may read,,that method doesn't cure it 100% either,,as the problem tends to return after a few months.

To be very honest,,I'm not sure anyone has ever cured the Limp Mode problem 100% without actually having to replace the Turbo itself.
As I said before,there is just so many things that can cause it...It can be a nightmare to find,and cure.




.

oh .. that sucks! but thanks for the honesty. iv done a lot of research and iv yet to find a thread where it was solved so i guess this is quite the noggin scratcher. perhaps its time to retire the motor and lookin into that petrol upgrade i have my eye on :P

MrFrisp

alsiet2011 wrote: »

oh .. that sucks! but thanks for the honesty. iv done a lot of research and iv yet to find a thread where it was solved so i guess this is quite the noggin scratcher. perhaps its time to retire the motor and lookin into that petrol upgrade i have my eye on :P

No bother at all..

If you decide to keep it,,let Us know how you get on with it.

Shame to have to retire it though.




.

brian_m

alsiet2011 wrote: »

oh .. that sucks! but thanks for the honesty. iv done a lot of research and iv yet to find a thread where it was solved so i guess this is quite the noggin scratcher. perhaps its time to retire the motor and lookin into that petrol upgrade i have my eye on :P

I have the newer model a4 tdi (b7) that was suffering a limp mode problem something similar, changed the turbo and other parts on mechanics advice but it did not fix the problem.. after some online research i carried out it was a €14 actuator that controls a set of flaps on the inlet manifold that was causing the problem... although your problem does sound turbo related (over boost) it is worth checking the smaller possible causes first before shelling out for expensive parts

alsiet2012

Hello,

I had to return under a new user name since I got banned for some reason before.

ANYhow - i wanted to let you all know the status of the car. I've decided to keep it, but even better the limp mode turbo problem is resolved.

all it took was a good long spin to dublin to clear her out. i reckon my driving very short distances to work the last year clogged up the vanes and all it needed was a good airing on the open road. nice and simple! so shes as right as rain now!

alsiet2012

hello.
i fixed the turbo issue - charge pressure control deviation - by simply driving it hard for a long trip. clearly must have been something clogging the vanes or lines or something. delighted now issue is resolved. still have car - 200,220 miles now

alsiet2012

hello.
i fixed the turbo issue - charge pressure control deviation - by simply driving it hard for a long trip. clearly must have been something clogging the vanes or lines or something. delighted now issue is resolved. still have car - 200,220 miles now