VW TDI forum, Audi, Porsche, and Chevy Cruze Diesel forum banner

What is the main problem/solution?

  • Clean the vanes again with Mr. Muscle!

  • Change the turbo and actuator!

  • Take the car to workshop and go to play Golf - you both!

  • Sell the car - it has already 120.000 kms!

1 - 12 of 12 Posts

·
Registered
Golf 2.0 TDi year 2005
Joined
·
5 Posts
Discussion Starter #1
The patient is Golf 2.0 TDi year 2005 BKD-engine.

When accelerating it gets into Limb-mode because of excessive boost in turbo. And gives the related error code, and the same can also be seen in pressure changes via VCDS.

VCDS shows that the ECU's requested pressure will be exceeded by actual pressure in turbo, when hitting the pedal to metal - and when that situation lasts long enough, the engine goes to limb -mode. That will happen every time. But also - if the acceleration is done carefully and following that the vacuum figure in the pipe from N75 block to vane actuator (yes, I connected there a gauge to see the vacuum) will not go too high, one can get even 170 km/h speed w/o issues.

We cleaned the turbo by loosening the exhaust pipe from turbo and turning it to aside and sprayed Mr. Muscle into the turbo - twice; washed it with water. Moved the vane actuator with vacuum pump to get that better cleaned. Now the vanes move easier and all the way when giving vacuum with a separate vacuum pump. But so far we have not installed any camera to see how it behaves on highway speed - does it move and return when the vacuum from N75 is changing accordingly.

We also tested that the vacuum from N75 behaves normal way - the N75 valve solenoind works. We tested it with two separate N75's valve blocks - both working same way: when idle, the vacuum is 20. When gas pedal is hit, the vacuum drops in second to <5 and jumps then backwards close to 20; depending of the rpm.

We eliminated EGR action/leak by closing its actuator's vacuum line - no changes; we also tested its possible leak. Nothing.

If we pump vacuum to the pipe line from manifold to the N75 valve block, it does not keep the pressure steady - it slowly leaks. Should it not? But if we pump the vacuum to the pipe line from valve block to the turbo actuator, that does not leak at all.

We do not understand why the system does not work properly, but goes to limb mode because of excessive boost, if we have N75 working properly and we can move the vanes with a vacuum pump.

Can anyone help what to test/check or even where do we have the possible mystery key?


Rgds,
Two old neighbours from Finland having quality time with golf. ;)
 

·
Premium Member
Joined
·
9,674 Posts
First posts normally go in introductions else you could get a free fix and we never see you again!!!

Forum Rules and Guidelines

This is a new forum layout which is owned by a company last year that doesn't give a dam with loads of bugs which have been reported in the new thread. There is no TDI Wiki at the moment or original similes which they refuse to install. It doesn't show the car spec/location.

Add your car specs to your signature that will show on every post you make.

Car spec now shows not for all members.

Release Notes

We Are Live - Community Feedback

This has been talked about many times.

I've made a poll which no one has posted in, there are a few votes and comments.

Do you like the new forum features?

Wiki pages have been restored as of 7th December, I asked where is the link it should be on top of the main forum.

You need to get your motor scanned (preferably with VAG-COM\VCDS) for any error codes logged in the ecu and post them, that will save a lot of guessing and check systems out.

Thread moved to general.
 

·
Registered
Golf 2.0 TDi year 2005
Joined
·
5 Posts
Discussion Starter #3
You need to get your motor scanned (preferably with VAG-COM\VCDS) for any error codes logged in the ecu and post them, that will save a lot of guessing and check systems out.

Thread moved to general.
Maybe I need to scan it with VCDS then.
 

·
Registered
Golf 2.0 TDi year 2005
Joined
·
5 Posts
Discussion Starter #4
I did scanning - no more any Fault codes; I just cleared them yesterday again.
 

·
Premium Member
Joined
·
9,674 Posts
I did scanning - no more any Fault codes; I just cleared them yesterday again.
Scanned with what a generic scanner as we don't know if you have VCDS?

You should have posted the error codes before erasing them or look at the VCDS log file and post them in CODE tags.

Clearing error codes only clears the ecu memory you still have to fix the problem.

You need to get your motor scanned (preferably with VAG-COM\VCDS) for any error codes logged in the ecu and post them, that will save a lot of guessing and check systems out.
 

·
Registered
Golf 2.0 TDi year 2005
Joined
·
5 Posts
Discussion Starter #6 (Edited)
OK - as I wrote at the start up there, I have used VCDS here to read the live data and fault codes and graphics. I purchased it from Ross-Tech some 10 year ago and used ever since. No problem with it - good software.

"VCDS shows that the ECU's requested pressure will be exceeded by actual pressure in turbo, when hitting the pedal to metal - and when that situation lasts long enough, the engine goes to limb -mode. That will happen every time. " That means that also the error code P0234 appears - 16618/P0234/000564 - Ross-Tech Wiki

We have tested different ways trying to eliminate possible errors, and always before doing the new test, I have cleared the codes with my VCDS in order to give the possibility to start from a clean table - errors erased. But still the over boosting appears and error of excessive turbo boost P0234 appears - and the same can be seen on graphics: the ECU is asking a certain pressure in acceleration, but the actual goes over that figure - and stays there too long during the acceleration; and the limb-mode comes....

As I described above, the vacuum of the actuator is OK - no leaks. The N75 solenoid acts fast when not connected to actuator pipeline, but when the pressure in actuator pipeline is measured when accelerating the car, it keeps the low pressure too long. Where does the information to that N75 solenoid come from originally to ECU - from MAF?


EDIT: The text in the link above:

16618/P0234/000564 - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)
Possible Symptoms
  • Malfunction Indicator Light (MIL) ON
  • Boost Pressure too high
  • Reduced Power Output
Possible Causes
  • Hoses incorrectly connected, disconnected, blocked or leaking
  • Boost Pressure Control Valve (N75) faulty
  • Boost Pressure Sensor (G31) faulty
  • Turbo Charger stuck/faulty
Possible Solutions
  • Check Charge Pressure Control System
    • Perform Output Test (to check the Turbo Charger)
    • Perform Basic Setting (to check the Charge Pressure Control)
    • Perform Pressure Test to locate Leaks
  • Check/Replace Boost Pressure Control Valve (N75)
  • Check/Replace Boost Pressure Sensor (G31)
  • Check/Replace Turbo Charger
 

·
Premium Member
Joined
·
9,674 Posts
VAG Error Code: 16618/000564

EOBD II Error Code: P0234

Fault Location:
Boost Pressure Regulation - Limit Exceeded (Overboost Condition)

Possible Cause:
Malfunction Indicator Lamp (MIL)(K83) active.
Boost Pressure too high.
Reduced Power Output.

Hoses incorrectly connected, disconnected, blocked or leaking.
Solenoid Valve for Boost Pressure Control (N75) faulty.
Manifold Pressure/Boost Sensor (G31) faulty.
Turbocharger stuck/faulty.
Exhaust Gas Recirculation (EGR) Valve blocked.

Possible Solutions:
Check Charge Pressure Control System.
Read Measuring Value Blocks (MVB).
Perform Output Test (to check the Turbocharger).
Perform Basic Setting (to check the Charge Pressure Control).
Difference of set value boost pressure vs. altitude sensor signal > 200 - 1275 hPa.
Perform Pressure Test to locate Leaks.
Check/Replace Solenoid Valve for Boost Pressure Control (N75).
Check/Replace Manifold Pressure/Boost Sensor (G31).
Check/Replace Turbocharger.
Check and clean Exhaust Gas Recirculation (EGR) Valve.

Description:
The boost pressure sensor responds to pressure changes in the intake manifold. This pressure is created by the turbocharger and changes with accelerator pedal position and engine speed. The Engine Control Module (ECM) uses this information to assist in diagnosis of the barometric pressure (BARO) sensor and to provide engine overboost protection. The boost pressure sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The Engine Control Module (ECM) supplies 5 volts to the boost pressure sensor on the 5-volt reference 2 circuit, and provides a ground on a low reference circuit. The boost pressure sensor provides a signal to the Engine Control Module (ECM) on a signal circuit relative to the pressure changes. The Engine Control Module (ECM) monitors the boost pressure sensor signal for voltage outside of the normal range. The Engine Control Module (ECM) calculates a predicted value for the boost pressure sensor. The Engine Control Module (ECM) then compares the predicted value to the actual signal.

As taken from my new Free EOBD II Error Codes software
 

·
Premium Member
Joined
·
8 Posts
I have an 03 Jetta so not the same as yours. But the ALH has a check valve in the vacuum system. When that is leaky it causes problems similar to what you describe. No codes. No VCDS indication. I replace mine every year (25k miles). $18 from id parts.
 

·
Registered
Golf 2.0 TDi year 2005
Joined
·
5 Posts
Discussion Starter #9
I have an 03 Jetta so not the same as yours. But the ALH has a check valve in the vacuum system. When that is leaky it causes problems similar to what you describe. No codes. No VCDS indication. I replace mine every year (25k miles). $18 from id parts.
Can you give any directon to locate it? Where in the system it is?
8669
 

·
Registered
VW Golf MK5 2005 2.0 GT TDI 140 4motion BKD
Joined
·
8 Posts
The patient is Golf 2.0 TDi year 2005 BKD-engine.

When accelerating it gets into Limb-mode because of excessive boost in turbo. And gives the related error code, and the same can also be seen in pressure changes via VCDS.

VCDS shows that the ECU's requested pressure will be exceeded by actual pressure in turbo, when hitting the pedal to metal - and when that situation lasts long enough, the engine goes to limb -mode. That will happen every time. But also - if the acceleration is done carefully and following that the vacuum figure in the pipe from N75 block to vane actuator (yes, I connected there a gauge to see the vacuum) will not go too high, one can get even 170 km/h speed w/o issues.

We cleaned the turbo by loosening the exhaust pipe from turbo and turning it to aside and sprayed Mr. Muscle into the turbo - twice; washed it with water. Moved the vane actuator with vacuum pump to get that better cleaned. Now the vanes move easier and all the way when giving vacuum with a separate vacuum pump. But so far we have not installed any camera to see how it behaves on highway speed - does it move and return when the vacuum from N75 is changing accordingly.

We also tested that the vacuum from N75 behaves normal way - the N75 valve solenoind works. We tested it with two separate N75's valve blocks - both working same way: when idle, the vacuum is 20. When gas pedal is hit, the vacuum drops in second to <5 and jumps then backwards close to 20; depending of the rpm.

We eliminated EGR action/leak by closing its actuator's vacuum line - no changes; we also tested its possible leak. Nothing.

If we pump vacuum to the pipe line from manifold to the N75 valve block, it does not keep the pressure steady - it slowly leaks. Should it not? But if we pump the vacuum to the pipe line from valve block to the turbo actuator, that does not leak at all.

We do not understand why the system does not work properly, but goes to limb mode because of excessive boost, if we have N75 working properly and we can move the vanes with a vacuum pump.

Can anyone help what to test/check or even where do we have the possible mystery key?


Rgds,
Two old neighbours from Finland having quality time with golf. ;)
Sounds like a very similar problem to what Im having - similar engine, BKD 2005 140bhp. Mine goes into limp mode still and what seemed to trigger it was having an EGR cooler failure so I decided to do an EGR delete and cooler delete (£300 new in the UK). I get P0234 overboost error.

What Ive done so far:
  • removed EGR cooler
  • removed EGR using kit
  • New vacuum actuator
  • New fuel temp sensor (previous error code)
  • New MAF (bosch)
  • new vacuum lines
  • Turbo removed and stripped own/cleaned (wasnt that dirty)
  • Car had been remapped (no history) so had it remapped back to stock with an EGR delete
Car was taken to a VW specialist who tested eveyrthing - turbo working fine, vacuum hoses ok.
They noted overboost and air mass readings too high (which explains why its overfuelling?)

My problem is its failing emissions (3x max limit) so I cant get the MOT on it.

Only thing I can think is that I noticed the flexi pipe after the DPF on the exhaust (straight off the exhaust clamp by the turbo) is a bit lose and I think gases leaking out - would this cause an issue? When driving car resonates at certain speeds which I think is the flexi pipe vibrating? Also wehn I was separating the exhaust form the turbo I had to use a plastic hammer on the DPF as it was stuck - could I have clogged the DPF?

Question to you - is your exhaust ok with no leaks - tight seal where the exhaust clamps to the turbo housing? Apparently exhaust leaks can cause overboost issues...
 

·
Registered
VW Golf MK5 2005 2.0 GT TDI 140 4motion BKD
Joined
·
8 Posts
OK - as I wrote at the start up there, I have used VCDS here to read the live data and fault codes and graphics. I purchased it from Ross-Tech some 10 year ago and used ever since. No problem with it - good software.

"VCDS shows that the ECU's requested pressure will be exceeded by actual pressure in turbo, when hitting the pedal to metal - and when that situation lasts long enough, the engine goes to limb -mode. That will happen every time. " That means that also the error code P0234 appears - 16618/P0234/000564 - Ross-Tech Wiki

We have tested different ways trying to eliminate possible errors, and always before doing the new test, I have cleared the codes with my VCDS in order to give the possibility to start from a clean table - errors erased. But still the over boosting appears and error of excessive turbo boost P0234 appears - and the same can be seen on graphics: the ECU is asking a certain pressure in acceleration, but the actual goes over that figure - and stays there too long during the acceleration; and the limb-mode comes....

As I described above, the vacuum of the actuator is OK - no leaks. The N75 solenoid acts fast when not connected to actuator pipeline, but when the pressure in actuator pipeline is measured when accelerating the car, it keeps the low pressure too long. Where does the information to that N75 solenoid come from originally to ECU - from MAF?


EDIT: The text in the link above:

16618/P0234/000564 - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)
Possible Symptoms
  • Malfunction Indicator Light (MIL) ON
  • Boost Pressure too high
  • Reduced Power Output
Possible Causes
  • Hoses incorrectly connected, disconnected, blocked or leaking
  • Boost Pressure Control Valve (N75) faulty
  • Boost Pressure Sensor (G31) faulty
  • Turbo Charger stuck/faulty
Possible Solutions
  • Check Charge Pressure Control System
    • Perform Output Test (to check the Turbo Charger)
    • Perform Basic Setting (to check the Charge Pressure Control)
    • Perform Pressure Test to locate Leaks
  • Check/Replace Boost Pressure Control Valve (N75)
  • Check/Replace Boost Pressure Sensor (G31)
  • Check/Replace Turbo Charger
I have same problem - everything checked and tested, keep getting P0234 and emissions too high. Have you checked exhaust for leaks next to turbo or flexipipe etc?
 

·
Registered
VW Golf MK5 2005 2.0 GT TDI 140 4motion BKD
Joined
·
8 Posts
I have ordered a recon turbo as I had a chat with a garage near me and they've had several cars which they stripped and cleaned turbos put them back on and still got overboost. Then they replaced turbos and it sorted the problem. I keep getting P0234 overboost and have gone through everything else now. Should get the turbo monday so will fit and report back...
 
1 - 12 of 12 Posts
Top