Need help keeping Lambda where it is...

[Super73]

The situation:

I am basically out of injector on motor..
When I put my wet N20 kit on it, IDC often climbs as Cyl Airmass climbs..
-- NA 505rwhp = 1.08 @ 6,900 = 94.5% IDC
-- Smallest N20 (single 57n jet) 710rwhp = 1.19 @ 6,900 = 100.2% IDC

I don't really run it on motor, and would like to up the fuel jet in the N20 kit to bring down the IDC. This part is easy.



The more complicated part..

I was on the dyno recently and found quite a bit of power on my smallest N20 tune up going from 660rwhp to 710rwp. I found moving from .82 lambda with 23* timing --> .77 lambda and 27* picked me up that 50rwhp... I made this fueling adjustment by simply putting a bigger fuel jet in the N20 kit. This means my PE multiplier is still at my previous 1.205 (0.83 lambda).

The problem this poses is my AFR ERR Histogram would now be off as I am looking for .77 when the PCM is commanding .83.

I am worried if I simply move PE 1.205 --> 1.30, IDC percentage is going to try and climb unless some other change is made and I am thinking that change needs to occur in the VE table (lowering VE in the upper cells). This would effectively be tricking the PCM, less air = less fuel.

I know the best solution would be to to put a set of bigger injectors in it and I plan to, but can't get to it before my next race Dec/4.




So, for the temp band aid, if I scale PE 1.205 --> 1.3 is there a direct correlation to VE?

I am effectively adding 7.9% fuel via the PE, can I lower VE that same 7.8% where PE is enabled (above 4,000rpm)?




Thanks for the input.

[Super73]

Interesting there are no thoughts on this.

[mowton]

If I understand the issue correctly, you are only worried about your Lambda Error calculation. Then I would just do the math long hand and make the changes per that....or you could just setup a user defined math for both commanded and error where as you use a Eq commanded value of .77 and an error function that uses that cmd value as well.

Changing the PE and lowering the VE will work but is a bit hokey I would think...

Ed M