I knoe it been beat to death....but, what are some of you guys numbers when pulling on a stock fuel system? Also what are some of you guys Lo and HI throttle settings. Im trying to tune my car via widband and highway and im in the -25 range and still getting 13.1. Ive read it adjusts timming and im not sure which way it is going, so.... while im at it how does the ecu adjust for for compensation? Ohh... there are tons more questions but these will do for now.
Safc tuning
- Thread starter Cya
- Start date
Cya said:
Very quick run down:
At WOT, I would say generally 10.5 is where the stock ECU likes to be. 11.5 is a safe tune. 12.0 is a good performance tune. 12.5 is getting quite risky. 13.0 is not good. At WOT, the ECU ignores sensor inputs (open loop), so it isn't compensating. That's why you can tune with the S-AFC. At idle you should see ~14.7, cruising will vary across the board because of ECU control, throttle postion and other variables. The stock ECU retards timing sharply at ~5,600RPM so SAFC tuning anything above 5,600RPM is relatively pointless.
SAFC advances timing as it pulls fuel due to the nature of dinking with the AFM frequency to trick the ECU into thinking that it's flowing less air, so it puts in less fuel, and puts in more timing advance. Basic SAFC 101. This is a good thing, and a bad thing. More timing + less fuel = more power BUT too much timing and not enough fuel are very bad. You probably have no way of knowing what your timing is once you're running, so set your base timing at 8-10 (for safety) and try not to advance the S-AFC farther than -20%. What you are doing is adjusting fuel while reducing the risk of over advancing timing (which can cause detonation). If you must go farther than -20%, then set all back to 0% and reduce fuel pressure to lean your motor.
You can go lower than -20%, but *I* prefer to try to keep the S-AFC as close to 0% as possible while maintaining proper AFR. You can always add timing later by increasing your base timing. While good in principal, I usually end up in the -18% range at the upper RPM. :icon_conf
The S-AFC is a TRIMMING TOOL, intended to FINE TUNE the fuel curve. It's not intended to be tweaked out -40%... Once you get your fuel dialed in, you can advance your timing a bit. Detonation is not your friend.
Disclaimer - All this assumes reasonable engine condition - boost levels - fuel and supporting mods... It's best to do this on a dyno, and with a professional overseeing your work. If you blow up your engine after reading this, it still 100% your fault. :biglaugh:
So pretty much what im getting is that as long as I tune it to 12:1 I will still have ample fuel? What if I retard my timming from under the hood?
You say it's not designed to do +/-40 but it goes to +/-50. Im sorry to ask such questions, but im just trying to understand as much as I can before a do anything extreme.
You say it's not designed to do +/-40 but it goes to +/-50. Im sorry to ask such questions, but im just trying to understand as much as I can before a do anything extreme.
Cya said:
base timing = timing as set by rotating the CPS with the diagnosic jumpered properly. See the TSRM for how to set your timing.
The SAFC is a generic piggyback that can go from -50 to +50 HOWEVER it is intended to be used as a FINE TUNER. It doesn't have the flexability of a standalone. The closer to -50% you are, the more you are advancing timing, and the less fuel you are putting in. Until the maftpro, there was really no good way to know how much you are advancing timing with any SAFC type piggy back. Under -25% has been *my* safe number (-20% target) that I've seen and used over the years.
Sure you can go higher (lower?), but at any amount of SAFC correction you have no idea how much you are affecting timing. Since timing advance (detonation) under WOT is an unknown and potentially engine destroying factor, it's better to play it safe and eliminate/reduce timing as a factor. You do this two ways. Reduce your base timing, reduce the amount of timing the SAFC is putting in.
To put it another way - Assume you are tuned for a 11.5:1 AFR on your wideband (very hypothetical - as in I'm making these numbers up):
Your way:
SAFC average = -40% | base fp = 43psi | base timing = 8
You are over correcting with the SAFC for a high base fuel pressure and have to run a low base timing to prevent detonation at WOT. At lower RPM and cruising you have retarded timing and generally crappy engine performance. You run rich at idle, and the ECU will likely have a hard time controlling the mixture (Look up Vf)
My suggestion:
SAFC average = -15% | base fp = 23psi | timing = 12
Your base settings are close to nuetral, with a bit more timing. The advanced timing gives more power and helps the turbo spool. Having a higher advanced base timing = more power across the whole RPM range.
Speaking generally, again. Some of the above would be skewed by other factors but I'm discussing within the circle of what you have control over. Set up your car to run well with the SAFC set to 0% across the board. Adjust your fuel pressure to get a reasonable idle and AFR. Set your timing a bit retarded to give a margin of error. Tune your fuel w/ SAFC. Then advance your timing SLOWLY. If you don't have an AFPR, then look at buying one because it should come before the SAFC.
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hmmm...good info, i've been looking into an Aeromotive AFPR. Any other suggestions, anybody sell kits for our cars?
Also, high throttle should be 70%, and low throttle should be 69%.
I don't like the Safc to do the "guess work" (interpolate) the fuel.
I don't like the Safc to do the "guess work" (interpolate) the fuel.
Cya said:
no offense, but if you dont know the basics you dont need to be tuning your car.
a/f = air to fuel ratio. the higher the number, the more air to fuel ratio and the leaner it is.
10:1 is 10 part air, 1 part fuel.
13:1 is 13 part air, 1 part fuel.
you are lucky if you didnt detonate the car running that lean under boost. be thankful for good gas and knock sensors.
imo you need to go back in and put 15% fuel back in straight away. then find someone to help you tune it correctly.
dbsupra90 said:
Well... thats part of the reasons WHY we have disscussions, to get our facts straight. And secondly, im not paying $160 per 1 hour dyno session if I don't know the im guarnteed more power, my money could be put into something more useful. I see nothing but benefits from KNOWING whats going on in my car which IM dedicating ALOT of MONEY, ALOT of TIME and MANY sleepless nights.
BTW everything is already back at zero, I only use the settings that one night and set everything back to zero after I had written everything down.
Lots of good info guys.....keep it coming.
Hmmm....Knock sensors, how does this apply when using the afc? How is it measured, what are some signs I need to look for?
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well this is true. but the questions should have been asked before you started tweaking. there has to be someone in your area familiar w/ tuning?
besides, w/ a wideband 02 you can do a rough tune- say 11:1 range on the street or track. then take it to the dyno for fine tuning. i can usually get them where i want it in about 3-5 runs. also, on an untuned car i generally pick up 30-40rw just from a conservative tune.
most important thing is always make changes in small steps.
besides, w/ a wideband 02 you can do a rough tune- say 11:1 range on the street or track. then take it to the dyno for fine tuning. i can usually get them where i want it in about 3-5 runs. also, on an untuned car i generally pick up 30-40rw just from a conservative tune.
most important thing is always make changes in small steps.
There are a few but they are wishy washy (at least the people ive spoken with) and want $80 per tune via longstretch of highway. So from what ive given I would want to turn the air up right?
Because when I turned it down and went WOT at-25% I got the 13:1.
Because when I turned it down and went WOT at-25% I got the 13:1.
Has anyone tuned a SAFC on a stock fuel system? I was looking on HPF and they offer a kit w/o a AFPR. I agree with what everyone has said so far but this just got me to thinking....
http://www.horsepowerfreaks.com/pri...HorsepowerFreaks/Horsepower_Kits/Stage_3_Kits
http://www.horsepowerfreaks.com/pri...HorsepowerFreaks/Horsepower_Kits/Stage_3_Kits
conservative tune is 11.5:1 range. most lean youd ever want to go is 12-12.3:1 it will make a little more power running that range, but less room for error. 11.5:1 range you can make really good power yet still have a good margin of safety.
as far as putting more fuel back in you need to change your -25% to around -10% then go from there.
yes you can use the afc to tune in any condition. ive tuned supras from near stock to over 400rw.
i have a really good friend that runs a dyno and knows supras and tuning really well. he is in virginia tho, which is ~200 miles from where you are.
as far as putting more fuel back in you need to change your -25% to around -10% then go from there.
yes you can use the afc to tune in any condition. ive tuned supras from near stock to over 400rw.
i have a really good friend that runs a dyno and knows supras and tuning really well. he is in virginia tho, which is ~200 miles from where you are.
If the knock sensors start reading knock will it show a CEL usually?
After my cams install I went out to get a AFR reading on my laptop and went lean from about 6200-7300. Scary when I got home and checked the data and saw it peaked at 13.0:1. I never threw a CEL and have never gotten one since I did my swap, but it does blink with the correct pins jumpered. I'm curious if it even works right.
After my cams install I went out to get a AFR reading on my laptop and went lean from about 6200-7300. Scary when I got home and checked the data and saw it peaked at 13.0:1. I never threw a CEL and have never gotten one since I did my swap, but it does blink with the correct pins jumpered. I'm curious if it even works right.