Thread: Understanding how to turn up the boost

Now that my car works and drives well, I have some questions for you guys. I don't quite understand how tuning works in junction with upping the boost, what I do know is that if I up the boost on my car I am going to need a retune. If the amount of fuel that is put into the engine is determined by the amount of air the MAF. So if the MAF tells the ECU xxx amount of air is going into the engine and then the ECU tells the injectors to dump the correct amount of fuel into the engine assuming the tune is correct. So why do I need a retune if I up the psi from 7psi to 10psi if all I am doing is putting more air into the engine? Is it that the maps are not there for anything above 7psi? Also, would I be maxing out my injectors at 10psi with a t25 at 3bar?


Setup:
99 lowport de+t
W10 T25
370cc injectors
Walbro 255
Calum Basic stock de+t tune

That's a perfectly reasonable question. The answer is not too complicated. Basically, like you said, the maps in the ECU are not mapped out for 10 psi. Once you get around 7 psi the maps max out and anything above that you get the same fuel an timing that you'd get at 7 psi. At 8 psi you might be okay, at 9 or 10 psi you're going to have major problems with lack of fuel.

The traditional answer to this problem has been a re-mapped ECU (like a JWT ECU) but these days people also go a little further and get tunable, daughter board modified OEM ECUs like Calum (used) or Nistune (new and used). There are other cheap tricks you can do instead like non-linear rising rate fuel pressure regulators sometimes humorously called FMUs or Fuel Management Units or sometimes just a fuel piggy-back unit is good enough like a SAFC or similar. More expensive methods also exist in the form of fully tunable "stand-alone" ECUs.

Now I do have a calum basic ecu with data logging feature. I got my chips from alfsentra and he said the tune was conservative and the car seems to be running a bit rich and will have my wideband installed this tuesday. How can I view these maps to see if this tune is mapped for anything over 7psi?

That's a question for the Tuning or CalumSult sections of the forum. I'm not sure how to view the maps burned to the chips of a Calum Basic ECU.

Thanks Ben, you have been a huge help thoughout my project.