I'm very aware that this isn't the best tuning device evAr, so no need to remind me haha.

With that out of the way, on to my questions...

I'm looking for tips/advise from people who've tuned using a VAFC (or similar) in conjunction with an adjustable fuel pressure regulator.

I have a VAFC 2, ADJ. FPR, Fuel pressure gauge,and AEM UEGO wideband o2 setup, so I can safely street tune this setup. In the long run, I do want to have it fine tuned on a dyno, however, for the time being I'd like to get it relatively close.

I know that it's best to ADD fuel with the FPR to the point where it's rich and SUBTRACT it with the VAFC to get it where you want it, as this advances ignition timing. My question, is how rich do you want it before you subtract fuel.

As it stands right now, my idle ignition timing is set at 17.5* advanced, my fuel pressure at idle WITH vacuum is ~40psi. With no adjustments on the VAFC this equals a low 12:1 afr at 5000 rpm dipping to ~11.8:1 by fuel cutoff. I then used the vafc to MINUS fuel to the point where it is 13:1 AFR from 5000 to fuel cutoff. To get the AFR to 13:1 at fuel cut I had to minus 14%. Is that excessive? Does this sound like I'm on the right track? The car feels great but I know the butt dyno is a terrible way to tell.

So I guess basically, my question is, how rich do I want to make it before I minus fuel? And what kind of numbers to I want to see on the VAFC, like what is considered excessive?

Sorry for the long post, haha I like to be really thorough. If you need any more information to help me out just let me know.

EDIT: The car is a 1993 H22a1 Prelude. I originally posted this in the Prelude forum, however, I thought I'd get better quality responses over here.

 

You are on the right track. Dial in the AF ratios & you should be just fine.

 

Thats good to know. I was just unsure as to where to set the AFR BEFORE subtracting fuel with the VAFC. For example if I set it to 10:1 with the FPR then used the VAFC to bring it back to 13:1, would that be more beneficial than having it at 12:1 with the FPR and making it 13:1 with the VAFC? As it is right now, like I said the car feels really strong, no issues at all, I'm just wanting to make sure I get the most out of the setup that I can for the time being. Thanks for the response.

 

Don't over think it.
Set your base fuel pressure to around 44 psi static and tune from there etc.

 

Will do, thanks a lot for the replies man.