1.7L TDI Racing Engine No Longer Runs After Winter Break

Hi everyone,

I'm really starting to run out of ideas about what's going on.
Last year, I parked my race car in the garage every autumn and haven't touched it since. Now, he doesn't want it anymore. The engine is a very heavily modified AFN. He starts well and then stalls after 1 second with 2 out of 3 control units. 0 281 001 421/422, 028 906 021 BF, Year of manufacture 96
With the third engine control unit, part number 0 281 001 584, and 028 906 021 EK, (model year 1998), it runs (only tested at idle).
My problem is that the other two control units have a higher performance tuning.
All engine control units have been modified, as well as the wiring harness. The sensors are from the Golf 3 AFN. There is only the engine control unit (diagnoseable) left, and the immobilizer has been removed from all control units. The fuel injection pump is a Golf 4 11mm pump (0 460 414 987)
Another interesting feature is that when I disconnect the battery switch, the control unit (and the entire car) becomes completely without power. The current from the failing alternator is diverted through a resistor to prevent voltage spikes.


What I have done and checked:
-Error codes read out with different results:

Monday, 06, July, 2020, 18:53:03:46872
VCDS -- Windows-based VAG/VAS emulator runs on Windows 10 x64
VCDS Version: DRV 19.6.2.1
Data Status: 20191020 DS308.0
www.Ross-Tech.de





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Address 01: Engine Electronics Label file: DRV\028-906-021-AFN.lbl
ECU Part Number: 028 906 021 CK
Part and/or Version: 1.9l R4 EDC 00SG 0802
Encoding: 00002
Operating Number: WSC 01315
VCID: 5ABC40B8C6A8619F88-4B14
2 error codes found:

01266 - Relays for Filament Bulbs (J52)
31-10 - Interruption / Short to Ground - Sporadic
01269 - Injector Start Valve (N108)
31-00 - Interruption / Short to Ground

Readiness: Not Available


Saturday, July 11, 2020, 00:26:53:46872
VCDS -- Windows-based VAG/VAS emulator runs on Windows 10 x64
VCDS Version: DRV 19.6.2.1
Data Status: 20191020 DS308.0
www.Ross-Tech.de





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Address 01: Engine Electronics Label file: DRV\028-906-021-AFN.lbl
ECU Part Number: 028 906 021 CK
Part and/or Version: 1.9l R4 EDC 00SG 0802
Encoding: 00002
Operating Number: WSC 01315
VCID: 5ABC40B8C6A8619F88-4B14
6 error codes found:

01266 - Relays for Filament Bulbs (J52)
31-10 - Interruption / Short to Ground - Sporadic
01269 - Injector Start Valve (N108)
31-10 - Interruption / Short to Ground - Sporadic
01268 - Quantity Set (N146)
18-10 - Upper Limit - Sporadic
01268 - Quantity Set (N146)
19-10 - Lower Limit - Sporadic
00539 - Fuel Temperature Sensor (G81)
30-00 - Interruption / Short circuit after positive line
01237 - Fuel Shut-Off Valve (N109)
31-00 - Interruption / Short to Ground

Readiness: Not Available


Furthermore, he initially had the coolant sensor G62 installed.
The majority of the time, however, is only
01266 - Relays for Filament Bulbs (J52)
31-10 - Interruption / Short circuit to ground
in the control unit, as it no longer exists. With this error, the car ran perfectly last year.

- Coolant temperature sensor G62 replaced

- Measured the movement of the fuel injector from the control unit under motion

- Controlled mass points

- Diagnostic Findings: When the active engine control unit (EK) is active, all fuel injectors and valves can be heard. When the inactive engine control units (BF, CK according to VCDS), the fuel shut-off valve cannot be heard, but according to AutoData, it receives the correct voltage during starting.

- Cable harness disassembled and inspected for damage to the insulation.


Regarding the possibilities of VCDS, I must admit that I am a beginner, so please assume that if something is not listed above, I have not done it.

I would really appreciate your help.

Best regards,
Hinnerk

Hello,

Since all your engine control units have been modified, no one here knows whether errors are being displayed correctly, along with the corresponding error conditions, etc.

Are the error entries in all three control units identical?

If not, my suggestion would be to purchase a control unit with the original data set, depending on what has been done to the WFS. In this case, it would already be possible to ensure correct entries in the error memory.

Quote:

will go off again after 1 second

Actually typical for the engine start-stop system, in this case, however, there should be a corresponding entry in the engine control unit's error memory.

How did you handle the WFS issue with your car?

The error logs you posted, however, point more towards a cable problem (possibly a problem with the marten?) with the pump connectors or the wiring to the fuel injection pump.
Delete and see what comes back after turning off/on.

Best regards, Rainer

Hi Rainer,

Having an original control unit is an idea, and I will start looking for one. Then, one has another point of reference.

No, the fault codes are not identical; most of the time, only the indicator relay is present. The two protocols with the most entries have been posted.

The chip responsible for the start-stop system in the control unit was reprogrammed, and the start-stop control unit was completely removed.
In all the error logs, there was never anything mentioned about the immobilizer.

Regarding the wiring harness, I agree with you. However, I haven't found any traces, and the resistance measurement of the wires to the fuel pump was within the normal range...
Since I was also suspecting the wiring harness first, I'm working on a second one, but it will still take a few more days to complete.

Are there diagnostic blocks that provide helpful information during the startup process to determine the cause of the engine shutting down again?

Greetings
Hinnerk

Entries in the fault memory seem to indicate a communication interruption between the MSG and the VP37...

Hi everyone,

Thank you. I'm going to take a closer look at the wiring harness again.
I will get back to you as soon as I have something new.
Or the new cable harness be completed.

Greetings
Hinnerk

Hi everyone,

such a small update.
I have re-examined the wiring harness and, based on the schematic, checked and measured all the wires.
- No errors found

Then I also borrowed another 1.9 TDI ECU from my garage and tested it. As expected, the ECU had locked due to the missing start-up lock. However, the car ran significantly longer than with the two ECUs that were not working. The car was running and was parked, and one could no longer hear the starter being cranked like with the other two control units.
Furthermore, the diagnostic test for the control unit functioned properly, similar to the other active control unit, and not just partially, as with the inactive ones. Below is the read error memory:

Monday, July 13, 2020, 15:25:45:46872
VCDS -- Windows-based VAG/VAS emulator runs on Windows 10 x64
VCDS Version: DRV 19.6.2.1
Data Status: 20191020 DS308.0
www.Ross-Tech.de


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Address 01: Engine Electronics Label file: DRV\028-906-021-AHU.lbl
ECU Part Number: 028 906 021 AH
Part and/or Version: 1.9l R4 EDC SG D4A
Encoding: 00000
Operating Number: WSC 00000
VCID: 55A65384AFB64EE7A5-4A68
1 Error found:

17978 - Engine Control Unit (ECU) disabled
P1570 - 35-00 -

Readiness: Not Available

If you don't agree, I think the control units are obsolete. Bad / Cold solder joint where the calibration chips were installed.

Best regards,
Hinnerk

Hi everyone,

I can at least report some partial successes.
The engine is running again.....
The cause was mechanical. The car had been stored in the garage over the winter and wouldn't stay running with the modified control units. It ran fine with the older, less modified control units, but then it ran too rich - resulting in soot at idle, but a smooth engine running.
What I did now was to give the old engine a few bursts of gas, and lo and behold, the first two seemed to accept it reluctantly, and it jerked a couple of times when it revved up. In addition, there was a lot of black smoke, which could probably be due to all my attempts to start it.
Then I plugged in the problematic device again, and lo and behold, it was working perfectly.
Okay, a problem has been fixed and two new s have been added.
1. What could be the mechanical cause? For me, it seems that the fuel metering unit is slightly clogged, which prevented the control unit from accurately regulating the fuel quantity during the transition from starting to the cold-running phase.
2. The problem with inconsistent diagnosis and the malfunctioning actuator diagnosis on the tuned control unit. (No problem in the original series) (Fuel shut-off valve is not audible and the turbocharger pressure regulation is not audible)
At least, I need to check if this continues to occur after the diagnosis, because in the meantime, I have cleaned the contacts (they actually looked pretty good before).

Best regards,
Hinnerk

Hello,

If you have installed a vent cover (in front of the intake manifold), make sure it remains open and that the mechanical actuation is not broken.

Also, this flap must always be open, except when stopping.
Not that a solenoid fails and the increasing vacuum in the vacuum system after starting immediately closes the valve.

A stuck quantity control system can generate an error message in a normal engine control unit, and possibly even cause the engine to stall.

Best regards, Rainer

Hi Rainer,

Thank you for the feedback.
No, I don't have one.
Further up, I had posted about the intermittent errors related to the EPS.
Of course, it's possible that electrically, something isn't quite right. But I interpret the behavior during the first gas strokes and then the rapid improvement in the responsiveness more in the direction of mechanics.
Understood, I might be wrong and I appreciate any ideas.

Greetings
Hinnerk

One more tip for storing diesel: Current normal diesel fuels in the EU contain biodiesel, which, in the long run, has a tendency to cause sticking and promote corrosion.

No problem as long as the car is running, prolonged standing with the substance in the tank and ESP is not recommended.

In this case, I would prefer to (only for storage) fill it with Ultimate or something similar and then drive it. If, of course, there is no biodiesel (rapeseed methyl ester) present, then it shouldn't be.

Currently, I had a problem with a tractor with a 50-liter tank. The fuel had spoiled because it was simply too old.

Best regards, Rainer