Boost Vs Afr

[EdGTR]

Hi people, I have a r32 gtr with a cat back and pfc. Its been tuned quite a while ago but is quite happy but recently i fitted a zeitronix wide band o2 sensor. This has opened up a whole other side of things to look at. I have been doing quite alot of freeway driving and with the help of a friend have been cleaning up the maps around the speed limit area. I have been able to get a noticable gain in response and also smoothness in these areas but the big question is what do people think that the relation between boost and afr's should be? As in if you are cruising along the freeway and the afr is 14.7 either with the standard 02 sensors on or off and you come to a hill what do you think your afrs should drop to with say 2 psi and then 4 and so on? I know people say low 12s is good at full throttle but its the middle im interested in.

[JonnoHR31]

aim for around 14.7 at real low boost (2-4psi) then go gradually towards 11.5-12 at the points where you hit full boost. the afr line from 0 boost to full boost should be fairly linear. everyone has their own opinion but this has worked well for me.

[EdGTR]

Thanks that is what i was thinking, it richens up a bit with boost and sits around 13.8 at low boost 2-4psi and then drops to about 12 flat. Its good because i can data log and then see all the graphs on the same page.

[brother_david]

As far as i reckon you should aim for 13.5 when coming on boost, appaerently its supposed to give the best pressure raise :S Its what i run and works great, other then that i run 15.2-15.3 at cruise and about 12 at full boost

[BoostedBarge]

So if you're running 15.2-15.3 at cruise, have you disabled closed-loop? Do you have it off all the time? I'm thinking of doing the same thing.

[JonnoHR31]

yer you would disable closed loop if you spent enough time on the map to get it nice

[BoostedBarge]

Hmmm. I really need to get my own AFR meter. I borrowed a mate's once and tuned the cruise/light throttle stuff, but it would be really good to have an AFR meter pernamently and to tune the 2-4psi area.