In a four-cylinder engine, the number one piston is typically the one located at the front of the engine, closest to the timing belt or chain. This configuration can vary slightly depending on the engine's design, but conventionally, it is the first cylinder in the firing order. In inline engines, it's often on the left side when viewed from the front of the vehicle. In V engines, the designation can differ based on the manufacturer’s specifications.
on the engine
Turbo position is on the right front next to the p/steering pump if your A4 is a turbo unit if not it mite be a A4 L only no turbo specification. You can not install turbo because the piston are different from the turbo engine.
Under the hood on the back wall behind the cylinder block
I believe on this model you need a special tool to push the piston back. You can go to the website I have below click the link below!
Each cylinder has 5 valves. Three intake valves and two exhaust.
The 2003 Audi A4 has an inline 4 engine.
The 2001 Audi A4 has an inline 4 engine.
The 2006 Audi A4 has an inline 4 engine.
The 2008 Audi A4 has an inline 4 engine.
The 2007 Audi A4 has an inline 4 engine.
The 2013 Audi A4 has an inline 4 engine.
The 2004 Audi A4 has an inline 4 engine.