I recently purchesed a 02 bugeye w/ vf48, fmic, ebc, 800cc injectors, and a high flow maf sensor . The car came with a "BREAKIN TUNE". Which the previous owner paid to have done after mods. The maf was a nightmare, injector scale was set at 430, ect. Car ran a solid 5 IAM and stumbled quite often. I have read many post and lots of version of how to tune. the best resorce i found was the " The complete tuning guide" by BAD Noddle. All the steps in his guide are very valueable and a must read for everyone.
Getting to the point. I found out if you don't have the right injector scaling and right maf scaling, you almost need to do both at the same time. I started tuning the maf until i was close, then i read many post on 800 cc injector scales. found anywhere from 540 to 800 scale. However most had a scale of around 760cc. so i used 760 as my scale. after doing this, i rescaled maf 5 times to get close. the idle was still off. i end up manually adjusting maf scale in romraider and tested a few times. This gave me a very smooth idle and range up to 2.60. I follow Bad Noodles steps from there. This is not said in many places, you must rescale maf several time to get it close(mainly due to inconsistant load conditions and thottle movement during tests.) I personally used romraiders maf tool and did trial and error as stated above for injector scale. I believe you can be a little off on injector size and scale maf to make up for the difference if you don't know exact injector size. I live in a area the has very little flat long roads, so i stop and start logger in hills and decel. I have just let the logger go all the time(uphill, downhill, stop, starts, ect) as long as log is long enough and the extra bad data isn't to long. it doesn't seem to throw off the maf scale enough to worry about. I did alot of logging in city traffic, using idle time for 1.20-1.25 ranges. and limited the thottle movement(kept steady/slow accel). I hope some of this helps someone. thanks to all the member who have contributed their input and time to help all us tune and make our subbies go.
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You will get a better idea in 20 minutes doing it that way than 3 hours of trying to get closed loop sorted