EFI tuning basics question

[blofly]

alrighty now this is probably a bit of a dumb question but I have to ask anyway! With all the aftermarket computers out there I have always read that you NEED them to tune your car for good horsepower results and driveability, but why do we need to tune the car again? the car already has the throttle position sensor, oxygen sensor and knock sensors so basically I can only immagine that the car should already know what the engine is doing right? only thought about it the other day and wondered how come the car really needs cuctom tuning

 

[Techo]

It's the computer that you must tune not the engine. The sensors on the engine tell the computer what it's up to & then the computer decides whats going to happen. So when you get a "custom tune" they rewrite the fuel & spark maps on your memcal to suit your engine. Just about all car dealers have their computers mapped for extra fuel & less spark advance to save the cat converter & to avoid pinging on their mass produced engines. A custom tune can take out this extra fuel when it's not needed, add some when it is, & give you extra spark advance if you like to shell out for PULP.

 

[Konker]

and in simpler form: when a manufacturer builds a car they must meet regulations and so on. thus when they make a computer to stick in it they find a balance between power and efficiency. putting an aftermarket computer only "tips" the balance (usually towards more power aye boys). hope this helps but any other questions keep them coming