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16 October 2006

Data Logs - Stock Baseline

In technical discussions about the 2.0T FSI engine in various online forums, a few topics have been hotly discussed recently. These include the effects of software upgrades (from various vendors) on:

  • Ignition timing & correction factors

  • Air/Fuel ratio (AFR) - mixtures that may be much leaner than original

  • Exhaust gas temperature (EGT) and the effects of high EGT on the turbo due to lean AFRs

  • Requested boost vs. actual boost (may reflect boost leaks from a failed diverter valve or crankcase breather valve)

...and of course with any power-related mod, what's the measurable gain?

Since I have not yet done any powertrain mods and the engine is well-broken-in with 20,425 miles, I decided that now would be a good time to take some baseline measurements that I can use to evaluate future mods. I met up with Jim who had been taking the same measurements on his own A3 (which has a software upgrade), and we used his VAG-COM to do the same logging on mine as a comparison.

The conditions were:
Fairly flat, straight, dry road. Full-throttle from about 2000 - 2200 RPM in 3rd gear until redline. A/C compressor off. Almost full tank of fuel, 93-E10, same type and grade as I've been using. 2 occupants. Temperature 7C (~45F), ambient pressure 1019.5 mbar. Two runs were conducted in opposite directions.

Click below for the gallery of graphs from both runs, plus a graph of the power measurement run we did earlier in the year:

2.0T FSI Baseline Engine Measurements

As I do powertrain mods, I can repeat the same runs and compare the results to this baseline.


11 October 2006

Trailer Light Wiring

In the rest of the world Audi provides plug-and-play wiring for trailer lighting. Since Audi doesn't offer a hitch for the A3 in North America, they don't offer wiring either. The European wiring kits are very expensive and don't correspond to US trailer wiring conventions, so importing one was not an option. (Click here for an article about my custom hitch.)

Since the A3 has a software-configurable variable-voltage lighting system for the taillights, and most models are equipped to detect failed bulbs, a solution had to be found that would work reliably, would not interfere with the car's diagnostics, and would avoid problems associated with how the A3 taillights work. I was able to do this using a trailer wiring converter that protects the car's circuitry and puts no load on the lighting circuits. When connected to the correct circuits (not the three tail/brake/rear fog bulbs on each side) it works perfectly, and if any taillight settings are changed (using VAG-COM, for example) it will not affect the trailer interface at all. The required converter is the Hopkins Manufacturing (Hoppy) 46365. To find one, search for Hopkins 46365 or Hoppy 46365 on Amazon, eBay or Google.

I have produced step-by-step instructions to guide you through installing the trailer lighting interface on the A3 in a problem-free manner. It's about a 1 to 1.5 hour job. These instructions are also useful for anyone wanting to open up the side panels in the cargo area and/or remove the subwoofer, since they contain details and photos on how to do so.

Click the image below to download the instructions as a PDF. The download file size is about 5MB. You will need a PDF viewer (like Adobe Reader) to view and print the instructions (not necessary on Mac OS X - PDFs open in the 'Preview' app).


UPDATE - A reader provided the following feedback regarding wire colors on later A3s:

The taillight wire was grey with light green tracer on my 2013. The wire bundle went to a connector where it then switched to grey with brown. Otherwise all the other wire colors were the same.

Enjoy towing safely with your A3!

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