jdmz

I got the SOS stage 1 installed on my AP1 and been trying to tune it with the fpr that it came with. Out of the box, my wideband o2 was reading it in the 13's at full boost which is way too lean. I am 7 full turns clockwise from the factory pre-set and can hit 11.4 at redline. It is 12.5 ish with less than redline rpms. According to the installation manual, I should be at just a tad bit over 11.5 a/f ratio starting from 1000 rpm and just exceed 12 a bit at 5000-6000 rpm. Do you guys think there is a problem with install or is the regulator faulty? I don't really want to turn the fpr too deep or damage may occur but it seems like i need to be richer.

s2000Junky

Sounds like your a bit too rich at 11.4. 12-12.5 is optimum for your low boost SC with the fpr. You wont get an exact linear fuel curve with your fpr, but anywhere between 11.5-12.5 is safe/good.

jdmz

Well if that's the case I am feeling a bit better about it. Just a bit nervous because I had to crank the fpr so much to get in the ballpark from preset. I was just thrown off because the manual was showing under 12:1 at 1000 rpm and up, I don't get to 12.5 until mid rpm. I will do some more testing today.

I am running a resonated test pipe and also a Borla cat back. Maybe that I'd the reason why I had to richer so much from present.

Sylvain2000

Just fyi

My first setup with my SC was exactly like yours. Plus Toda header , 70mm TP and exhaust. To get a good afr at wot i had to crank the rrfpr to max. But then cruising and part throttle was way to rich.

At Max the fuel pressure at 6psi of boost was really close to 100psi , that is a lot of pressure . I tried everything , (even against junky's advice ) bought a new rrfpr , cleaned my oem injectors , put the cat back ...

My guess is you got to run this setup with a 100% stock S.

s2000Junky

Yes, the rrfpr from the kit is calibrated for a bone stock w/cat s2k. So its not surprising for the majority of users with aftermarket exhaust and TP that they will need to exceed the pre set SOS adjustment, and thats ok to do up to a point, thats what the adjustment is for. I ran mine at 90-95psi long term to get a safe afr, but at the expense of some richer then ideal fueling at part throttle and out of vtec because its not a perfect calibration across the boards when you exceed the ideal window. If you have to crank the adjustment screw till its virtually buried at the locking nut/95+psi you should reconsider other avenues for tuning employment. Chances are pretty good you wont get to that point though as long as you stick to the stock psi pulley the kit comes with. Where you start getting into trouble is when you get greedy like I did and want to move to the next pulley size coupled with your breathing mods. Stock injectors dont operate consistently at 100psi and risk locking up which would be bad. They will take 90-95psi all day long though in my experience. Just keep in mind its a rising rate fpr, so at 60psi idle pressure, your roughly at 90psi redline.

jdmz

thanks for the information. My adjusting screw is still above the lock nut. See picture below. Do you still recommend that I get a fuel pressure gauge to monitor the pressure? I need peace of mind to drive this thing harder

s2000Junky

That adjustment amount looks very familiar. Its not a bad idea to have a pressure gauge, but based on the thread count on the adjuster there id say your probably ok if thats what you need to get a safe afr in 6k+ rpm range. You are getting close to not wanting to go much further though. At this range, you will find that the preload on the internal spring/diaphragm is a lot and smaller adjustments show bigger jumps in fuel pressure, its not linear at this point, so keep that in mind if you go to make further adjustments. Small 1/4 turns will do a lot.

What afr are you seeing consistently now at say 6500rpm? And near redline? How about bellow vtec rpm?

jdmz

I took it for a short ride today and it is around 11.5 at redline, 12.5 ish at 6500rpm, and 13-14 (I think) below 4700 rpm. I am not too sure on the below vtec as I've been testing the high end. Won't have time to take it out for another run for a while but what do you think?

s2000Junky

The top end is the most crucial, however you dont want to run overly lean down low either. There is a big difference between 13 and 14afr, so pay close attention to that next outing. 13afr would be the safe limit where id feel comfortable bellow 5-6k rpms on this set up, 12.5afr is great at 6.5k, and ideally would be the sweet spot for redline as well, however as mentioned its not a linear fuel curve with the set up so your going to have to figure out a safe/good compromise. 11.5afr is fine, but not needed to be that rich to be safe for your limited boost/set up and is leaving a decent amount of power on the table. 12.5 would be much better. But to get there, you may end up running to lean in the lower/mid range, so thats something you can explore/fiddle with when you have more time. I would not go leaner then 13afr up to 6k as mentioned, and you should start enriching to at least 12.8 by 6.5k and beyond that the fuel will richen up on its own and be what it will be. Thats my tip.

When you start getting greedy after your pallet has been wet for power here. Based on your top end afr of 11.5 and running a hfc, the next pulley size down for 1 more psi could put you in the sweet spot in the fuel curve, since that 1psi is not a linear increase across the rpm range, but just the top end, it would allow for limited enrichment needed but get you a leaner more ideal top end. In my experience, 1psi = roughly 1point of afr, so 11.5 to 12.5 etc. But hone in what you have first before exploring for more, but just saying there are some options in some cases to get a little more safely without having to make any big leaps in investments.

jdmz

When you say under 5000-6000 rpm, do you mean starting from 1000 rpm - 5000-6000? I appreciate all the great info.