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Discussion Starter · #1 ·
Hello guys,

I have an ongoing issue with my 2.5TDI AJT engine with assumed low charge air pressure. This engine has the EGR blanked and EGR intercooler removed. Previously been remapped.

The problem - While sitting on the drive and someone revving the van to 4k revs the turbo arm only slightly moves at high revs. When the van is being driven it is gutless and slow and feels like straight 5cyl 2.5l no turbo. Struggles to push past 3rd gear on steep hill. Top speed up hill under 40 mph. This is not a camper, just an empty day van.

Backstory - After starting issues presented, which resulted me in changing two looms between ignition and fusebox, and fusebox and engine, new glow plugs fitted. Van would then turn over, but wouldn't stay running. The van was then taken to a garage, where it sat for months while it had ongoing issues with the garage. Van was removed again 7 months later and since then turbo not kicking in. I believe by this time the van hadn't been used properly for around 1 year. The van wasn't started at all for a 6 months period during this time.

What I have checked/done since receiving the van back:
  • Vacuum hoses checked and replaced using diagrams.
  • N75 solenoid checked for operation using bench power supply, resistances checked between terminals and 12v power at cable on van between pin 1 and earth.
  • N75 swapped with EGR solenoid to rule out the solenoid.
  • Banjo fitting on turbo compressor removed, cleaned and refitted. Washers present.
  • Pressure hose taken from the turbo compressor (banjo) and fitted directly to the turbo actuator, thereby bypassing all vacuum hose and solenoid assembly. Van revved to 4000 rpm and very small movement at the turbo arm.
  • Actuator checked with the hand pump, doesn't look like it leaks.
  • Later checked the actuator using a bike pump and the actuator has full turbo arm movement under 20 psi (i cant actually read what it is as the pumps minimum value is 20 psi and the actuator operates halfway between 0 and 20 psi).
  • Checked the air filter for blockages, old but not blocked.
  • The turbo arm has been manually operated, its stiff but can be moved by hand.

It seems to me that there is low charge air pressure from the compressor side of the turbo, as I can get movement on the actuator using bike pump at under 20 psi. Is there anything else I should check which can affect charge air pressure? Any known leaks etc?

Any help would be appreciated as I am really scratching my head with this one.

Many thanks for taking the time to read.

Joe
 

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Hmmm. Loads of guessing.

I've got a good idea what's going on but it's virtually impossible for anybody to reliably help you diagnose this engine without you owning a registered copy of Ross Tech VCDS (£99) as some tests are required; do you have VCDS?

HH
 

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Discussion Starter · #3 ·
Unfortunately, I do not own this software. Maybe you could shred some light on what you think maybe the problem is?

I am planning on rotating the turbo later by hand to check for free movement, and considering removal of the turbo for cleaning.
 

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Discussion Starter · #8 ·
Hi HH,

I received a VCDS cable this past week purchased from ebay. Supports VCDS lite freeware and paid. I have yet to purchase the software.

I had lots of issues getting the interface to connect to the ECU but after some communication with the supplier managed made a little head way.

Firstly I will say that I have attempted connection via 2 different laptops, one running windows 10 and the other windows 11. Same issue occurred on both computers in which the interface would be found in the test page, but the connection was "poor" and after saving the test, the VCDS didnt recognise a successful test had been completed. This meant I couldnt receive the serial number to register the software to my laptop.

On the phone to the supplier we attempted connection by updating USB firmware which made no difference. The guy then asked me to manually change the USB latency via device manager options in which the default setting was changed from 12ms (I believe) to 5ms. This then updated the VCDS test connection status to "good" (not excellent as normally seen when watching other people use the test feature).

I then attempted connection to the ECU through carrying out module searches and auto scan features but this didnt work with connection errors showing on the software. I started clicking on the individual modules one by one and only when I got to the immobiliser did the interface actually connect and display some information.

There were two faults on the immobiliser, one which was low signal and the other I cant remember, I cleared these and since then they have not appeared again. I wasnt surprised to see the low signal fault as the immobiliser ring is not around the ignition and the old key had been taped to the ring.

Now that I had managed to connect to the VCDS via the immobiliser, the about page displays a serial number and I can upgrade the software.

Unfortunately, the only information I can receive from the van is the immobiliser. No other modules are working or displaying information with connection errors showing when attempting connection to them. This includes all the basic engine and ABS modules. I believe the immobiliser is actually separate to the ECU with being behind the dash. This means that currently there is no connection to the ECU.

From what I read online, there could be a module or something on the van holding up the connection line preventing modules from connecting. Apparently after market radios can cause this issue, but my van currently doesnt have one installed.

I have been looking into ECU faults on these transporters and I am starting to suspect this maybe the problem.

This was taken from ECU TESTING website:

"Engine ECU malfunction for the Volkswagen T4 will ultimately prevent the vehicle from starting. When this ECU has faulted communications to the engine management system will not be possible."

Also not directly related to the T4 this was written regarding the Golf, caddy, and T5 transporters:

"When the ECU fails you will normally notice that the engine will not start intermittently, you may find that you need to turn the ignition on and off many times before the engine will eventually start. You may also find that the engine will not start at all and the engine management light is no longer illuminating on the instrument cluster.

If you have tried to read the fault codes from the engine system you may also find that you are unable to read any fault codes, or you cannot communicate with the ECU at all.

All these symptoms are a good indication that your engine ECU may be faulty..."

This is how my vans issue started initially, with intermittent starting issues which quickly resulted into not starting at all via the key. The first garage got round this by crossing the starting solenoid, but then we later found the wiring loom had a melted wire between the ignition key and the glow plugs (fully rectified now).

Obviously I cant say for sure but I believe the damaged loom was causing an incorrect voltage at the ECU, leading to damage.

What I know is:

  • The ECU is not connecting at all to the VCDS,
  • No dash warning lights illuminating before the starting issues last year or now, even considering all the current faults and with changing two looms and disconnecting all cables while carrying this task out.

I am sorry for the long post.

I am now considering sending the ECU away for testing. I am not entirely sure it's worth purchasing the VCDS at this stage as I am not actually able to connect to the vans ECU properly. Something is preventing a decent connection.

Any thoughts at this stage regarding all the information I have provided so far would be appreciated. Is the ECU damage what you were thinking could be the problem?

I look forward to hearing back regarding this.

Thank you, Joe
 

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Okay, there's nothing wrong with the ECU, this will be 1 of 3 things:

1) useless cheap chinese lead from Ebay

2) water damage / corrosion in the loom across the top of the engine

3) pirate copy of VCDS not directly from Ross Tech.

HH
 

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Discussion Starter · #14 ·
Hello HH,

Right, I have carried out a continuity test of the loom between the diagnosis point to the immobiliser, the immobiliser to the ECU using official wiring diagrams. There is power and there is no radio connected to the K line. Everything came back fine there. The loom was inspected at various points including at the ECU connections and there is no sign of damage.
I have purchased an official VCDS HEX V2 interface and using up to date software.
I have carried out Auto scan using the chassis code as found in the log book. This is the results of a full scan.

Chassis Type: 70 (70 - VW Transporter/Multivan (1991 > 1996))
Scan: 01 02 03 08 15 22 25
VIN: WV1ZZZ70Z2H130152
-------------------------------------------------------------------------------
Address 25: Immobilizer Labels: 6X0-953-257.lbl
Part No: 6X0 953 257
Component: IMMO 0008
Coding: 00001
Shop #: WSC 00000
VCID: 7DA7F71344EF0B03A49-4B1E
WV1ZZZ70Z2H130152 VWZ1Z0B2022104
No fault code found.
End----(Elapsed Time: 01:46, VBatt start/end: 14.5V/14.5V. VIgn 0.0V)------

I also carried out another scan for a different chassis number as the year in brackets matched my van and these are the results.

Chassis Type: 70 (7D - VW Transporter/Multivan (1996 > 2004))
Scan: 01 02 03 08 15 17 18 19 22 25 35 37 56
VIN: WV1ZZZ70Z2H130152 Mileage: 439800km-273279miles
-------------------------------------------------------------------------------
Address 17: Instruments Labels: 7D0-920-xxx-17.lbl
Part No: 7D0 920 902 P
Component: T4-KOMBIINSTR. VDO V01
Coding: 00411
Shop #: WSC 02757
VCID: 313F1B23C8373F63701-5184
No fault code found.
-------------------------------------------------------------------------------
Address 19: CAN Gateway Labels: 6N0-909-901-19.clb
Part No: 6N0 909 901
Component: Gateway K<->CAN 0001
Coding: 00000
Shop #: WSC 02757
VCID: 70B9DE2703BD766B3FF-5184
No fault code found.
-------------------------------------------------------------------------------
Address 25: Immobilizer Labels: 6X0-953-257.lbl
Part No: 6X0 953 257
Component: IMMO 0008
Coding: 00001
Shop #: WSC 00000
VCID: 7DA7F71344EF0B03A49-4B1E
WV1ZZZ70Z2H130152 VWZ1Z0B2022104
No fault code found.
End----(Elapsed Time: 03:08, VBatt start/end: 14.5V/14.5V. VIgn 0.0V)------

When I have manually played around with the modules, the only two I can get results back are from the instrument panel and immobo.

Any suggestions?

Joe
 

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Run engine upto temperature then:

Start VCDS > Select > 01-Engine > Measuring Blocks -08 > group 000 > switch to basic settings > TDI Timing

Select engine type from drop down menu (ACV is fine)

What's the average value on the timing graph ?

HH
 

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Discussion Starter · #16 ·
Hi HH,

Thanks for taking the time to reply, unfortunately I cannot connect to the 01-Engine. I receive the error "No response from controller!"

I will post a thread on VCDS forums regarding connection.
 

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Are you able to post an image of the label on the ECU just to confirm which label file you should be using.
I assume you’re a paid up RossTech user as otherwise you wouldn’t be able to post on their forum, but the 1st thing they’ll do is request a full scan. If you’re not picking up the ECU then they’ll have the same problem with this.
 

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Discussion Starter · #19 ·
Hello guys, I have had a break through, the H wire was damaged in the loom in front of the engine like you said HH. I have repaired this now and able to get comms to ECU. There were some more damaged wires, but I took continuity tests on them and they seem fine. When I previously took the continuity test, I checked the two orange twisted cables, not realising at the time the immobo to ECU grey/white wire was the main ECU coms connection. This was the only damaged wire I found.

Lots of codes, I have the air pressure sensor disconnected on the manifold when took the first reading. Here are the results of the auto scan:


VCDS
Windows Based VAG/VAS Emulator Running on Windows 11 x64
VCDS Version: Release 22.3.1(x64) Data version: 20220407 DS337.0
www.Ross-Tech.com
Dealer/Shop Name:
Workshop Code: 000 00000 000000
Self-Diagnosis Log
Friday,05,August,2022,15:14:59:58974
VIN: WV1ZZZ70Z2H130152 License Plate: T400 JDG
Mileage: Repair Order:
Chassis Type: 70 (70 - VW Transporter/Multivan (1991 > 1996))
Scan: 01 02 03 08 15 22 25
VIN: WV1ZZZ70Z2H130152
-------------------------------------------------------------------------------
Address 01: Engine Labels: Redir Fail!
Part No: 074 906 018 AK
Component: 2,5l R5 EDC 0000SG 3905
Coding: 00002
Shop #: WSC 02757
VCID: 5F9BAD9BEE23F913965-4B7A
WV1ZZZ70Z2H130152 VWZ1Z0B2022104
5 Faults Found:
17946 - Fuel Shutoff Solenoid (N109)
P1538 - 35-10 - Open or Short to Ground - Intermittent
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-10 - - Intermittent
17964 - Charge Pressure Control
P1556 - 35-10 - Negative Deviation - Intermittent
17552 - Mass Air Flow Sensor (G70)
P1144 - 35-00 - Open or Short to Ground
17957 - Boost Pressure Regulation Valve (N75)
P1549 - 35-10 - Open or Short to Ground - Intermittent
Readiness: N/A
-------------------------------------------------------------------------------
Address 25: Immobilizer Labels: 6X0-953-257.lbl
Part No: 6X0 953 257
Component: IMMO 0008
Coding: 00001
Shop #: WSC 00000

VCID: 7DA7F71344EF0B03A49-4B1E
WV1ZZZ70Z2H130152 VWZ1Z0B2022104
No fault code found.
End----(Elapsed Time: 01:37, VBatt start/end: 14.5V/14.5V. VIgn 0.0V)------

I printed then cleared those codes, the only one which stayed on is the Fuel Shutoff Solenoid N109. This would make sense considering the new wire taken from the ignition to the Fuel solenoid.

The timing graph is all over the place. Jumping between 30s and 40s, sometimes goes to 31 or as high as 53.
 

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Discussion Starter · #20 ·
Are you able to post an image of the label on the ECU just to confirm which label file you should be using.
I assume you’re a paid up RossTech user as otherwise you wouldn’t be able to post on their forum, but the 1st thing they’ll do is request a full scan. If you’re not picking up the ECU then they’ll have the same problem with this.
Yes the guys on the Ross Tech site have been very helpful.

The ECU I am using is the bosch 0 281 010 462
 
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