Originally Posted by Avinitlarge
Originally Posted by Garage19
If you are looking at making 300 bhp i would drop your injector size by at least 20 %.
If you want a good idle injector size is critical with the original MS due to its 0.1 ms resolution.
I have had problems with it in the past.
With those big injectors you have you wil probably have idle pulse widths in the region of 1.8 ms (of which 1.2 is opening time). MS will not be able to closed loop very well as it can only change the fuelling by 1/6th (in this case) at a time.
If you go smaller injectors your idle pulse widths will go up allowing more accurate adjustment by the ECU and the closed loop will work well.
I was also told to use 500cc injectors to get 300bhp, They are actually 440cc with slightly upped fuel pressure
The idle pulse width is 2.2-2.3, There is a new code out called high res, It can get pulse widths in 0.001 res, I am thinking of upgrading to that, The only reason I am bothered about idle if for the MOT emissions test, Lambda 1 +/- 3 and all that
Surely the new code is 1/100th of a ms (0.01) not 1/1000th (0.001).
Where can the high res code be found? Are there many people running it?
If you do not have the smaller injectors backing your fuel pressure back down to 3 bar (43.5psi) will help increase the pulse width at idle. Are you measuring the base fuel pressure with the vac/boost ref pipe taken off the regulator?