around 70% max.

 

Care to share how you got the 20b afm to work with your S4 TII ecu?

I have a 20b afm and wired up the s5 style connector (in parallel) and it drove around just fine, but it refuses to idle. No mater what I set the variable resistor to its just too lean to hold any kind of idle and as you well know the Rtek doesn't have any real idle adjustment. I'll be running a very similar setup except with 9.4 rotors, should be interesting to compare results.

 

There is an air path going around the opening, and it's adjustment is blocked off with plasic filler, but under it is a screw, this is what you need to adjust for idle.

These are s5, but there should be something similar.

 

Assuming simply to much air at idle is the issue and closing the by-pass air doesn't fix, an adjustable FPR might just be the answer.

 

You are awesome! I knew there had to be a way! Unfortunately I just looked and I actually have the n390 afm (13b-re). The bypass functions a little differently; instead of a bypass tube w/ a screw the inner bore of the afm is larger than the diameter of the cone, so that even @ full closed there is a gap between the two which bypasses air and is thus non-adjustable.
(this is actually the 20B maf but the design is the same)




Maybe I'll just have to trade it for a regular s5 tII afm?

Perhaps, but then its too rich throughout the whole map...unless I spend a lot of time making low load fuel corrections. Although I just put in 750cc injectors and I'll start on the 4x720 injector preset so maybe that will be enough?

 

i'll trade you my s5 turbo one for your 20b... then find away to fix/work around this problem and let you know/maybe trade back? i know i'm going to need it when i put my Fd twins on it.. i maxxed out the stock s4 afm on the stock turbo... but you already know my secrets there.

Have you thought of upping the idle with the stop screw on the TB? just to get a high 1500rpm idle and then work your way down.

 

Well, that's not a half bad plan. I actually spliced in the s5 style connector so I can easily switch back to the s4 when/if needed.

I should be starting up my new engine tomorrow (with the s4 tII afm). Maybe it will be like magic an work when I throw the cosmo unit on later? My old engine never pulled good vac , so perhaps that will make a difference.