Diagnostic Interface Issues: Troubleshooting Guide

Hello,

My problem is that my VAG-Com interface only works when the engine is off. When the engine is running, it cannot establish a connection. However, I wanted to check the injection timing at the diesel pump and the torque, so the interface should also work with the engine running.
Does anyone happen to know the reason for this malfunction?

Best regards,

Hi.

Apparently, unnecessary background software can overload the entire PC-based automotive system to such an extent that, when the engine is running and placing a higher processing load on the system, communication can be disrupted.
Sometimes the engine misfire only occurs at higher RPMs.

However, I also experienced problems related to voltage fluctuations with immature or improperly matched adapters: the extra 2 volts of onboard voltage while the engine was running caused communication failures.

What applies to you now:

Hi Ulf,

Thank you for the tip. The car is a 2001 A4 with AKN engine, and the computer is an HP Omnibook with a Pentium 1000 processor. I bought the interface cheaply on eBay. I also suspect that the problem lies with the interface not working correctly.
Where can one get a decent KKL interface at the best price?

Best regards,

vikinger wrote:

Where can one get a decent KKL interface at the lowest price?

If it's primarily about being affordable: Building it yourself .

You can find circuits and accompanying tips, for example, in the "Tips & Tricks" folder on Rainer's website, specifically under "Diagnostic Adapter."