2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

S-AFC running too rich

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Old Aug 21, 2002 | 04:03 PM
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SilviaS13Drift's Avatar
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S-AFC running too rich

I think im running pretty rich with this S-AFC.. I finally got it figured out due to someones help... what should the percentages look like on high, and low throttle. right now im running at 7k rpm like 32% extra fuel... I have the 720cc secondarys...

Thanks
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Old Aug 21, 2002 | 04:40 PM
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Dyno tune.
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Old Aug 21, 2002 | 04:46 PM
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yup! put it on the rollers.
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Old Aug 21, 2002 | 05:04 PM
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Well, start leaning it out. Putting the larger injectors in richens the mixture up a ton, then you use the Super-AFC to tune for power.

Dale
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Old Aug 21, 2002 | 05:29 PM
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i only have the stock injectors, not nearly as big as yours and i have them on the minus side, way far from 32+%. do you have a turbo and lots of mods, than i can maybe see going positive.

okay i see you have quite a turbo, yeah maybe you need to be in the positive, but not that much if it is running rich.

Last edited by wpgrexx; Aug 21, 2002 at 05:40 PM.
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Old Aug 21, 2002 | 08:24 PM
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with 720's you should probably be "-"... not added fuel. unless you are running crazy boost. mine is at -14% with stock injectors.

so you are adding 75% more fuel them me LOL..
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Old Aug 21, 2002 | 09:21 PM
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the AFC is suppose to help when you have bigger injectors... the computer doesnt know that the engine has 720cc's in it.... Im not exactly sure how that works...

~Mike
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Old Aug 21, 2002 | 09:39 PM
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its not the SAFC's fault

i really don't see what the problem is, ur running rich....so put it on a dyno or get a wideband seperate(what i willl be doing) and use the SAFC to tune ur fuel.....after all thats what its meant for.
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Old Aug 21, 2002 | 09:39 PM
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yes.... the 720 injectors are 25% bigger then the stock 550's... since you now have 2 550s, and 2 720's. you have 12.5% more fuel. so if you lean the AFC to minus %12 from 4000-7000, the car would run the same as with stock injectors and it set to 0. or more or less... but you really need a wide band 02 sensor to tune it right.
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Old Aug 21, 2002 | 09:41 PM
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Basically, the Super-AFC doesn't work super well to add fuel with the stock injectors - the stock ECU can and will peg them out on certain occasions. This isn't a hard and fast rule, but a Super-AFC works best tuning in larger injectors on a turbo. On a non-turbo, the Super-AFC works best to optimize the stock fuel curve for better power - the ECU runs it pig rich at full throttle, and you can get some pretty good gains on an NA with a Super-AFC.

Anyhow, on a turbo, when you install the larger injectors, the ECU will run 'em just like the stock injectors. So, for every squirt the injectors do, more fuel is going in the engine - there is more fuel at the same pulsewidth. You use the Super-AFC to dial the fuel down for optimum power.

As I've said before, this setup works and works well for a stock turbo and probably a hybrid turbo as well. It's probably not enough for a large turbo - that's what I'm fixin' to be using the E-manage for .

Dale
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Old Aug 22, 2002 | 01:44 AM
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Ok so i should start from +/- 0 and just work my way up from that.. at times i run like all 4-5 greens on my A/F meter... I dont know if thats too good...

Thanks for the help, and the helpful hints...
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Old Aug 22, 2002 | 02:08 AM
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Originally posted by Scott 89t2
with 720's you should probably be "-"... not added fuel. unless you are running crazy boost. mine is at -14% with stock injectors.

so you are adding 75% more fuel them me LOL..
14% is what I was using on my S-AFC with my old TII....and that focker ran and ran and ran...so it looks like the tuning's done right on your side and was on mine!.

at 32%.....you're killing your gas mileage for sure...not that it matters with rotary's or anything. Turn that focker down! What turbine are you using and what boost are you running?
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Old Aug 22, 2002 | 10:07 AM
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From: Bremerton, WA
T3 hybrid turbo, and like 8-10 PSI... depends if its cold or not....

~Mike
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Old Aug 22, 2002 | 08:48 PM
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Turbo is too small.


-Ted
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