I was out doing a bit of playing with my lambda reader, and a mk2 Digifant. I know the WOT just richens up the whole fuel table, but I wasn't expecting it to move by so much! Cruising along, and on light, medium and relatively wide throttle opening, I was running anywhere between 14.5 and 17: 1 AFR. Put the boot in fully, and hit the WOT switch, and it dropped to 12/12:5: 1!!! Is that normal? Engine is fresh, a very recent rebuild including a mild cam and some diy headwork.
Digifant 2 cars at WOT, tend to run 14:1 at 2000rpm, then down to 12:1 at 3000rpm, which tend leans out to 13.5 to 14:1 near the redline. That is the profile I have seen on the dyno and on road over the years. You can make richer or enlean that profile with the AFM. However without mapping that does not change.
What do you recommend, Adlai? You're the man, when it comes to tweaking Digi. Should I lean it out a bit more? I was concerned it might be too lean then when driving "normally" or say briskly but not flat out.
Another thing has cropped up now is I can get very little adjustment on the CO with the Allen key. once the screw gets to about half way out, it doesn't seem to get any lower on the CO, winding fully in does increase it. How many "useful" turns are there from fully in?
It is a base mapping issue. Some cars might run a different profile, depending on the age of the ECU. Only rectified via mapping. I have done it for PGTI cars, and it is long and the gains are not all that, just more consistent fuel control to rev limit. CO adjustment is just a bleed to by pass the flap and the reported AFM resistance back to the ECU. If the flap is already set in a rich bias, then the CO will not change by a lot. You have to open the AFM and bias mechanically, which is not straight forward and assumes the engine is mechanically sound otherwise.
Just trying to get it right for idle and "tip in". We're allows up to 3.0 % ish, but I'd like to have it around 2 -2.5.
