Aircooled VW South Africa

Throwing this out there before I dig deeper... anyone managed to resolve similar issues?
My 115hp TDi is having some limp mode issues.
First a few comments about what is strange in comparison with my other TDi:

1. Especially when engine is cold in lower gears, there is quite a loud turbo cavitation sound when changing up.. (absent in my other TDi)

• Cycling the VNT actuator, the turbo spools up quite loudly... is this normal?

• Goes into limp mode at ~3500 rpm in 3rd.

• The actual maximum pressure does not seemed to be measured by VAG-COM.(maybe faulty boost sensor?!)

Do you have some advice for me after looking at the video?

Thanks a lot.
Eben

@ eben

Sorry buddy, can not help, but have a look at this site, may do something for you.

Herman

http://www.myturbodiesel.com/wiki/limp- ... di-engine/

Been there already Thanks
I've got two main suspects:
1. Sticking VNT vanes because of sooting...
2. Faulty boost sensor...

first check that any hoses you have on the system are all in good condition

@Tony Z hoses are OK. There is no "creep" on the actuator because of leakage as you can see.

eben wrote:Been there already Thanks
I've got two main suspects:
1. Sticking VNT vanes because of sooting...
2. Faulty boost sensor...

Hi Eben , plugging in a diagnostic tool would confirm which one is the culpret , they are both common faults and its a 50-50 toss-up without a fault code.
Our local cars suffer from the vanes getting clogged but i suspect you guys have a better diesel over there (with emmision laws being enforced) but the fact that there is also a wine from the turbo suggest you problem lies within... boost sensor would not cause a turbo whine.
good luck and keep us updated

What fault codes are you getting under engine ?

Thanks @splitfan.
I'm getting "Charge Pressure Control: Positive Deviation"
http://wiki.ross-tech.com/wiki/index.ph ... 557/005463

Maybe I should try force the vnt slightly to see if it is reaching the stops...

Hi Eben
As you might know , that means the car is overboosting , the std management has pre set parameters for boost press at certain rpm ranges whats happening now the vanes are stuck or cant move to the correct position thus creating the overboost fault .I see a turbo removal in your future hopefully the nuts and studs on the turbo are not to rusted/heat treated that you get them out without any breaking good luck. You can take out the boost sensor usually they are mounted on the intercoolers and give it a clean with some carb cleaner but my money is on the turbo being the culprit.You might want to look at the turbo oil feed and return pipes while you are at it.

Check the vacuum pipes on the actuator? Check the basic physicals before replacing the wizardry

http://www.youtube.com/watch?v=Z7k5yE1FAJs

This is interesting , they claim you can clean the vanes without having to remove turbo - depends on what Tdi you have , not much space to work with in Polo

I have removed my turbo 5x in last 3 weeks and can do it in 2 hours flat

Ohh yeah word to the wise DO NOT RECONDITION just buy a new one if damaged , cleaning is OK

regards

I've heard of this yes.. About €40

This is what it's like without load.... This can't be right... doesn't happen with my octavia... The turbo should not be spooling like this without load.
Must be sticking vanes..

Fixed it with oven cleaner...
Lets see how long it lasts..
Before and after graphs:
Yellow = Actual Boost
Green = ECU requested boost
Red = Engine Speed
Grey = Boost controller duty cycle.

If anyone is interested, this is how I did it:

• Remove the EGR to Exhaust manifold hose.

• stick some flexible tube in there carefully so it goes to the HOT side

• using a head with a tube (like you get for oils spray), spray foaming oven cleaner(Mr Muscle supposedly works best) into the pipe while clamping the top to make sure it goes down the tube.

• keep going until the foam just comes out or the EGR hole (it should not go up the exhaust manifold to the head!)

• Let is sit for about 5 minutes

• Using some pliers, carefully start manually moving the VNT actuator. YOu will find that is starts moving with less resistance.

• Let it sit a bit more

• WOrk the actuator repeatedly about every 15mins until you feel that it is moving freely and through the whole range or movement.

• Replace your EGR pipe

• Start the engine and rev it to min 3000 for about 30sec - 1 min, making sure your exhaust points to somewhere that you don't mind getting dirty.

• Check everything runs OK and go for a nice brisk drive using WOT in 3rd gear upwards to see if your engine is not going into limp mode anymore...

PS this is assuming your issue is sticky/dirty VNT vanes... this will not fix other issues with your turbo ie. seals, actuator leaking etc.