My car is fast on someday and slow on other days. I am talking about a big difference in pull and response.
I go to the same gas station, drive under same weather condition, never reset the ECU.
I notice on the day the car is faster, the boost always peaks a little higher. 1.3 bar on the slow days and 1.35 bar on the fast days. I did not touch the EBC, so I don't know why the boost changes.
Any idea?

 

any temperature and/or humidity variations on those days?

 

Wastegate fluttering to a very small degree maybe?

 

Depends on how much gas you got. My car feels the fastest at 1/4 tank or less. Weight plays a huge role in our 2.0L engine. The new Evo RS does 0-60mph in 4.4sec compare to 5.0sec on the Evo.

 

But the car feels fast for few days and then slow for few days, on and on...

 

Maybe the stepper motor perhaps? I'm just throwing out whatever comes to mind.

 

Welcome to owning a turbocharged car.

 

I would have suspected the EBC if it is like 1.3bar yesterday and 1.5 today. But in my case, 1.3bar and 1.35bar can not make this much power difference.