Introduction The original idea for a compact and portable troubleshooting tool for the Vanagon Digifant engine control system was spawned from attempting to track down a couple of intermittent and stubborn engine miss and failure problems in my 91 Westphalia a couple of years ago. I was having loss of power at highway speeds, and occasional engine start failures after the engine was at temperature. Visiting the local VW dealership, I was told that it would cost me approximately $350 to have them connect their computer to my Vanagon, and parts and labor would be added to that number. Desperate, I made an appointment, and after some thought about the expense, called and cancelled it. I then began some research to try to learn what makes the Digifant tick. I even got lucky, and found a VW Service Training Manual, which provided much valuable information. The 8691 ECU Monitor is a result of my effort to troubleshoot my own Vanagon, and avoid the high cost of dealership service. I hope it helps you as much as it has me.