TDI Tuning: Intermittent Power Loss Troubleshooting

Hello everyone,

First, I'd like to briefly introduce myself.

My name is Markus, I am 43 years old, and since the beginning of August 2005, after a long period of driving gasoline cars, I have been driving a diesel again. This time it's a Skoda Fabia 1.9 TDI-PD with its original power output of 74 kW, but it has been OBD-tuned by ***-Motorsport.

Here's what I've noticed with my Fabia, or the problem I'm experiencing is:

According to the speedometer, the car used to reach a top speed of 215 km/h (on a flat road).

About two weeks ago, I was on the highway again and wanted to let the car run normally. That's when it happened. I was in 5th gear at about 120 km/h (75 mph) and accelerated, but suddenly, around 180-185 km/h (112-115 mph), the power completely cut out without any warning signs, and the car could only reach about 140 km/h (87 mph). I then "limped" to the next exit, drove off the highway, turned off the engine for a short time, and then restarted it. Immediately, the usual turbo boost was back when I pressed the accelerator. After a few days, I went back on the highway and deliberately tried to reproduce the problem, which immediately happened again. I briefly turned off the engine while driving straight and immediately started it again. The result: The engine ran perfectly fine again.

I then checked the current fuel consumption on the onboard computer and found that it was only consuming about 6 liters at full throttle. This was completely different before (according to the onboard computer, at 215 km/h, the instantaneous consumption was approximately 11.2 liters).

Now my question to you diesel mechanics, who are undoubtedly more experienced in this area:

What could be responsible for the error or problem?

So far, I haven't been to the , and I also haven't had the error memory read out. It hasn't been possible for me due to time constraints.

I've already been searching extensively online for a solution to this problem, but I haven't found anything conclusive yet, other than encountering information about faulty VTG canisters and N75 boost pressure control valves.

Thank you in advance for your help.

Best regards,


markus-tdi

Hi,

incorrect search:
/viewtopic.php?t=8832&highlight=*575
/viewtopic.php?t=2002&highlight=*575

Please search for '*575'. Pay particular attention to the results in the 'VAG' forum (knowledge database).

Best regards, Rainer.

markus-tdi wrote:

I then selected the current fuel consumption on the onboard computer and noticed that at full throttle, it was only consuming about 6 liters. This was completely different before (according to the onboard computer, at 215 km/h, the instantaneous consumption was approximately 11.2 liters).

Did you read the 6 liters during the power loss, or at full (tuned) power?

If that's the case, I would say you've gotten a poorly executed tuning job.

Right, that possibility still exists .

If there was a "failsafe mode" (which you call "power loss") active before the tuning and it's no longer active after the tuning... then check the turbocharger boost control system. If everything seems okay, revert to the original software and see if the error still occurs.

Although the company ***-Motorsport is known for cutting corners, I would still check that out first.
Many years ago, I also had a problem with the seller of my generator because, after installation, the engine constantly stalled and eventually shut down (e.g., at night around 1:00 AM in Würzburg, about 200 km from my home, during extremely cold temperatures).
The problem wasn't a loose connection in the wiring harness to the fuel injection pump, but rather a faulty relay 109 . However, you can exclude relay 109 } based on your description of the issue.

Best regards, Rainer.

I don't want to come across as a know-it-all, but...

Rainer K. wrote:

3. Write vague and uninformative titles like "I urgently need help!" and get upset if the moderators give your thread a more descriptive title.

fulda wrote:

I don't want to come across as a know-it-all, but...

You are right -> Title changed

Thank you for the quick responses.

I've read about the "syringe test" before, but I can't really picture what it involves.

"@ulf: I was getting 6 liters per 100km during the emergency mode. When using full power, the consumption is significantly higher; it goes up to 42 liters per 100km in the lower gears and around 17 liters per 100km when accelerating in the higher gears."

markus-tdi