Does anybody still use Apexi Neos? Came across a great deal with a Rtek 1.7 and Neo, so I sprung on it. I know how to wire it and all that, but how do you set it up? Ive seen some stuff saying you have to set the Hi throttle to 98, and low to 1-98, not sure what this means, can anyone spread some light. My build is down below

1987 Rx7 Turbo II (S4)
Rtek 1.7
720cc secondairys
255lph fuel pump
parallel fuel system @ 40psi
stock turbo, ported wastegate
stock airbox
RB Rev TII exhaust
Stock engine port

Any input or thoughts are welcome, I do not want to go to a standalone system yet.

 

i've got a PFC, basically the same thing if you're just using the commander, lol

so the AFC lets you adjust fuel in a high load and low load situation (the older 5 **** one was just Rpm based), and the S4 TPS is setup only to read the first ~30% of throttle travel.
what they are saying is that low load is about 30% of throttle, which is 98% of the TPS, and the high load is everything above that, if that makes sense.

once you plug it in, and push the gas pedal a couple times it'll makes sense, if that doesn't

 

I used an apexi neo on a s4 t2 rtek 1.8. The problem is if you tap into the throttle for “low/high” the s4 tps signal only works from 0-~30% throttle range.

long story short, I used the output from the boost pressure sensor to determine where low and high are so it was boost level dependent.

i did a lot of reading on this before tapping into the boost pressure sensor signal. I believe I mostly got my info from dsm forums.

That was years ago and I’ve since been on apexi pfc so I forget the details, but it ran great and did what I needed it to do.

 

I’m using a NEO on my 13B-RE. Parallel twins on 16psi. 550/1050 injectors.
IIRC Low throttle is set at 35% and HI at 80%.
I’ve used Low throttle to tune cruising AFR and idle. HI throttle for everything else pretty much.
It has worked good for me so far.

 

I think I found the DSN forum you mentioned. You teed a vacuum line, or from the original pressure sensor on the passenger side strut tower? Or was is there an electrical signal tied into it? Also, do you remember if you set your low when it was at idle, or 0 psi?

 

I believe I only spliced into the factory t2 boost pressure sensor on passenger firewall 0-5v output signal wire so the safc can see it, similar to how you’d wire the safc to the tps. No vacuum tee should be needed.

I forget what I did for low/high values.

Just thinking about it right now, the stock t2 pressure sensor is a 2 bar map sensor, meaning it should have 0-5v output based on pressure level, correlating to 0 psi absolute to 2 atmosphere (29.4 psi absolute, 14.7 psi gauge).

the real question is what is the correlation, linear or polynomial. I’d assume linear. I’d think ballpark assumptions are good enough as the safc builds it’s own fuel map on a linear/polynomial correlation based on the low/high values which you’ll see on the wideband afr readouts.

sorry this is confusing, I moved to power fc ~6 years ago. My move to power fc was driven by a california state ref ticket, where I had a s5 t2 engine in a s4 car running s4 t2 rtek ecu. Had to rewire the car to s5 wiring with stock s5 t2 ecu, then moved to power fc after that madness.

sorry for the rant, but figured I’d give you some history on my car since I’ve been following most of your threads.

 

Adding:

quick google search found this thread which is probably one I read years ago.

Dsm forum safc with map sensor

I see why you mentioned teeing vacuum source. I used the factory boost pressure sensor signal wire mentioned in my post above. I also see their method of using an additional gm 3 bar map sensor to drive the safc is a great idea, especially since the 0-5v vs boost level is highly documented.

just a note of teeing vacuum lines: I’m a little weary of teeing into important vacuum (wastegate and boost pressure sensor) lines as diameter and length come into play in terms of response and accurate readings. Just keep that in mind.

for what it’s worth, I do believe providing signal to the safc from a boost pressure sensor is more reliable and beneficial than using a tps sensor, especially the s4 tps sensor.

 

yep its linear. it will take a little experimentation to find where one wants the low/high set point.

 

If it’s linear, I’d think 50% (2.5V signal from boost pressure sensor) would be 0 psi gauge, and 100% (5V) would be 14.7 psi.

could wire up the safc and have the ignition on, car off, and you should see 50% at the safc assuming you’re at sea level.

Either way, I think that would allow you to know the voltage boost starts at in the safc.

 

yep its something like that.

 

Thank you all for the input, DR_Knight and j9fd3s, you both reply to almost all my posts, and your answers are always very helpful. Thank you! I got everything figured out with it now I think, here are the links that put everything together.

https://www.rx7club.com/super-afc-12...c-neo-1013094/
https://www.dsmtuners.com/threads/bo...vement.440377/

Ill post once I get it going and let everyone know the results, and maybe a semi detailed install, in case anyone want to install one, which is unlikely.

 

Hope it works out for you.

a write up on this would be a good idea as it seems to just be tribal knowledge, and people will continue to use safc’s.

 

+1, ive got the settings for the 5 **** AFC for the S4 and S5. it would be nice to have it in one place