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Discussion Starter · #1 ·
Okay guys, i'm relatively new to tuning and to 3s's. The previous owner had the SAFC2 tuned by a friend of his. Only thing is, i have an open-atmosphere BOV and was having deceleration idle problems, which i believe isn't super uncommon. So i watched a couple of videos on it, read some of the posts on here and Stealth316, and was able to fix my issue. But since i changed the settings, it backfires (a lot) almost every time i coast in gear. it's not massive, but you can hear it popping away. Can anyone help me with the settings and give me reccomendations on what to set everything at? It's a '91 Stealth, rt/tt. Thanks yall!

PS. mods that might make a difference with the safc-2:
Big Bore 99 lifters, AEM TruBoost controller+gauge, AEM UEGO wideband, Tial Q bov, NGK BPR8EIX iridium plugs, Non-billet DR650's, EGR blocked, Hotwired Walbro 255lph fuel pump, Fabberge FMIC kit, Boomslang harness, 560cc Evo injectors, ATR downpipe + Single Shot, gutted pre-cats

Once again, thank you all!!
 

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1993 Stealth RT/TT
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To confirm. When you're coasting and you are off the throttle it is popping? Does it recovery when you tip in throttle right away? That would be decel fuel; a function of the OEM ecu and not tuneable by the SAFC. (This is of course assuming that the car is properly tune and isn't loading up and causing the popping)
 

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Discussion Starter · #3 ·
To confirm. When you're coasting and you are off the throttle it is popping? Does it recovery when you tip in throttle right away? That would be decel fuel; a function of the OEM ecu and not tuneable by the SAFC. (This is of course assuming that the car is properly tune and isn't loading up and causing the popping)
Thanks niterydr. yes, when i'm coasting and my foot is off the throttle it starts popping, and yes, the moment i start back on the throttle it stops backfiring. To my knowledge, the ECU hasn't been properly tuned.
Something that i forgot to mention when i first posted this thread was at idle, when it sees anywhere between the slightest amount of pressure on the gas pedal (usually just under 1%) and about 10% throttle, the engine/rpms lope. I don't know how else to describe it besides loping. and before I changed the SAFC-2 settings, it never did this. Sorry for neglecting to mention this before.

Side note: super cool name! I wanted to do NiteFury but it was already taken.
 

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1993 Stealth RT/TT
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Thanks niterydr. yes, when i'm coasting and my foot is off the throttle it starts popping, and yes, the moment i start back on the throttle it stops backfiring. To my knowledge, the ECU hasn't been properly tuned.
Something that i forgot to mention when i first posted this thread was at idle, when it sees anywhere between the slightest amount of pressure on the gas pedal (usually just under 1%) and about 10% throttle, the engine/rpms lope. I don't know how else to describe it besides loping. and before I changed the SAFC-2 settings, it never did this. Sorry for neglecting to mention this before.

Side note: super cool name! I wanted to do NiteFury but it was already taken.
What are your throttle settings? For a SAFC there are two maps. A "low" and a "high". Those translate to a set throttle %. I'll usually do something like 25% low and 65% high to start. Then anything 25% and under is the "low" map and 65% and up is your high map. This means low is idle and cruising, high is WOT and more boost related activities. The SAFC blends between the two between the throttle points.

"Niterydr" is a throwback to forums that had a maximum 8 character spelling limit for names. In high school I had a 93 talon turbo that was all blacked out with some red on it...kind of like "Kitt" from the Night Rider series (I know that wasn't a DSM in that show). It's just stuck for 20+ years.
 

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Discussion Starter · #5 ·
What are your throttle settings? For a SAFC there are two maps. A "low" and a "high". Those translate to a set throttle %. I'll usually do something like 25% low and 65% high to start. Then anything 25% and under is the "low" map and 65% and up is your high map. This means low is idle and cruising, high is WOT and more boost related activities. The SAFC blends between the two between the throttle points.

"Niterydr" is a throwback to forums that had a maximum 8 character spelling limit for names. In high school I had a 93 talon turbo that was all blacked out with some red on it...kind of like "Kitt" from the Night Rider series (I know that wasn't a DSM in that show). It's just stuck for 20+ years.
My throttle setting are set at 35% low, and 60% or 65% high. There is a noticable change in power once you get above 35%. I appreciate the help. I'm a relatively new owner, and have done a lot of reading but I still have a ton to learn

I just got the KITT reference. That's very cool! It would make a great custom license plate.
 

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1993 Stealth RT/TT
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What are the % on the low and high? Typically low ends up similar to the mathematical difference in stock vs aftermarket injectors. High ends up targeting a wot fueling lambda/AFR of your desire.
 

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Discussion Starter · #7 ·
What are the % on the low and high? Typically low ends up similar to the mathematical difference in stock vs aftermarket injectors. High ends up targeting a wot fueling lambda/AFR of your desire.
I can get you my high throttle settings later, i’m sorry I don’t have them in front of me at the moment.
My low throttle % are:
800 / -27%
1400 / -25%
2000 / -24%
2600 / -25%
3200 / -24%
3800 / -24%
4200 / -24%
4600 / -24%
5000 / -23%
5400 / -23%
6000 / -23%
6600 / -23%
 

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1993 Stealth RT/TT
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That is directionally accurate. I've never been a fan of over 30% correction.
 

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Discussion Starter · #9 ·
That is directionally accurate. I've never been a fan of over 30% correction.
no kidding? so i have those settings right? or at least close to?
My high throttle % are:
800 / -21%
1400 / -22%
2000 / -23%
2600 / -25%
3200 / -27%
3800 / -28%
4200 / -29%
4600 / -30%
5000 / -30%
5400 / -29%
6000 / -28%
6600 / -28%
thanks for the help!
 

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1993 Stealth RT/TT
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Gasoline Stoic is 14.68:1. E10 is 14.1:1. Most fuel today is E10.

Ideally get a WB02 (Wide band o2) and shoot for 1.0 Lambda off boost. Narrow Band 02 (NB02) is what your factory ecu uses to Trim around stoic. STFT (short term fuel trims) and LTFT (Long term fuel trims) are used to keep the vehicle running around stoichiometric AFR (air fuel ratio) in closed loop (aka with 02 feedback).

Wide open throttle or Open Loop Fueling target AFR/Lambda is vehicle dependent. Many are targeting 11.0 Gasoline AFR +/- .2 points or .75 Lambda.
 

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Discussion Starter · #14 ·
I might try leaning out the Lo table a little bit at lower rpm, and see if it helps the loping. I´m also thinking it might have to do with my throttle position sensor, the other day at idle I noticed the SAFC2 was reading between 0.6% and 0.7% throttle at idle, and a lot of the time i´ve noticed it return to about 0.3% when my foot is completely off the throttle. A quick blip of the gas pedal usually causes this to return to 0.0%, and the idle stabilizes there.
 

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Discussion Starter · #15 ·
Update: Leaning out the lower Ne points did not work. It still started loping from the moment i gave it gas up until about 8-9% throttle. i was, however, able to shorten the 'loping' range by adjusting the Decel Air %'s. It now only lopes up until about 6-7.5% throttle. It also cured the issue of not returning to 0.0% throttle at idleThe RPM's bounce between 500-600 and 900 rpm. Nothing else seems off, the correction is staying about the same, voltage isn't massively fluctuating, but the moment it starts loping, the AFR gets really lean, really quick, and in a moment it's lean enough that the wideband o2 blanks.
 

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Discussion Starter · #17 ·

the photo without the red circle was taken from the bottom up, where the mas meets the Y pipe. You can sort of see the lip where they’re supposed to join, and how they’re kind of separating at the bottom.The other picture is from the top, and I circled where they start to separate. Do you think this would cause a leak?
 

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You need to log your ECU or at least view live data... everything you are doing will be with one eye covered with your UEGO as the only point of reference. Evo injectors will always idle like crap (rich) due to major latency difference with 3S - need better management or different injectors to be optimal. Heat range "8" plugs are also unnecessarily cold for what you have, atm.

What spring is in your TiAL Q? Why not use a QR instead for now...?

Have you even pressure-tested for leaks? Definitely sounds like you have some.

Everything needs to be on point first. Tuning an S-AFC should not take more than an hour or so start-to-finish.

-sent from my Galaxy S22 Ultra
 

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Discussion Starter · #19 ·
I haven't pressure tested for leaks yet, and i'm not sure what spring is in the Tial Q. I just got this car a few months ago and DM'd the previous owner asking him about those. I'll let y'all know when i find out. I'm on the list at a local speed shop to get an AEM v2 with speed density installed, as well as dyno tuned (they've worked on the car before).
Should I buy a datalogger? which one would y'all recommend?
 

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If you are already planning on switching to a standalone, then just bide your time until then instead of messing with it now... unless you absolutely need it to drive better beforehand. Better hope (or confirm) that the shop specializes in these cars and can/will work out any and all bugs before hopping straight onto a dyno, otherwise, you are looking at more time, money, and effort.

-sent from my Galaxy S22 Ultra
 
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