I bought a 1997 Golf GTI 2.0 last year because I just needed some cheap wheels. The gas mileage has never been great, but since I don't drive that much I didn't really care. It feels like it's running fine, but obviously 20-21mpg no matter how you drive it isn't going to cut it.
I decided to look for an exhaust leak.
I learned 2 things:
1) I have some form of aftermarket tubular exhaust headers (I'm thinking eBay or OBX)
2) I have a leak nearly 1-2 inches behind the O2 sensor in the connection from the exhaust header to the catalytic converter. I'm guessing it just some bad fitment with the donut seal right there.
How bad is this? It feel like someone gently blowing out (quite soft, but definitely more than a 'pinhole'). Could this be the culprit even though it's behind the O2 sensor? (Only behind by 2 inches tops)
Let me know what you think. I'm planning on fixing the leak and perhaps swapping out what sensors I can (O2, maybe the coolant temp sensor per http://javalins.wordpress.com/vw-gol...-common-fixes/ page).
New air filter, oil, oil filter, distributor cap, plugs, pug wires. I wonder if maybe I should get an ECU that's flashed for this 'after-market headers / loud glasspack muffler' combo it's sporting in addition to the K&N on the intake.