How is the performance upgrade achieved from an ECU reflash

[sek]

Hey All,

Apologies in advance if this has already been covered.

I recently got the APR ECU upgrade done on my MK6 GTI which i'm really happy with. It got me thinking, with an ECU reflash how is the performance upgrade achieved? Is it mainly playing with the power / torque band and increasing the boost? If it mostly concerns increasing the boost, does anyone know what the stock boost is and what it is after the reflash?

[Nuggos]

Explanation to how it works
VWVortex.com - ECU reflash - how do they work?

Google is your best friend

and forum blabber about boost How much boost for APR tunes ? - VW GTI MKVI Forum / VW Golf R Forum / VW Golf MKVI Forum / VW GTI Forum - Golfmk6.com

that might help a little

[sek]

Cheers!

I'll read up on it.

[Beer Baron]

to understand it, first you need to understand what an ECU does.

the ECU = engine control unit.

it's a computer that controls the delivery of fuel and the timing of ingition events to the engine (it can control many other things but these are the basics).

in your GTI the ecu also controls the boost pressure.

it does all this buy taking in various inputs (usually things including: throttle position, cam or crank angle - to determine where in the cycle the engine is and to calculate rpm MAP or MAF, they stand for manifold absolute pressure or mass air flow from memory a GTI uses a hotwire type MAF). so the ECU takes all these inputs and those inputs tell the ecu which part of a map to reference at any given time. that map contains figures for fuel delivery and ignition timing.

what a reflash does is re-write that map with more "aggressive" figures in those cells. in the case of a modern turbo car which has boost controlled by the ECU it also raises the boost across the rpm range.

that's usually where the biggest/easiest gain comes from. simply add more boost and more fuel.

it's not quite as simple as all that. some parts of the map may actually 'need' less fuel as they may be so overly rich from the factory.

but the basic idea is it re-writes the fuel/ign and boost maps in your ECU so the same inputs as before now give a different amount of fuel/ignition advance and boost. that gives you more power.

this is only possible due to the large safety margins that are built into the factory tunes. if the car was tuned to the peak of it's components from the factory just doing a re-tune would do nothing for you.