Okay when you go +10 Is this adding more fuel and timing over the base ecu maps? Or is -15 adding more fuel and timing over the ecu base maps?

My car seems to run the best fully maxed out To +50? Does this mean i need bigger injectors? Please help.

Depending on the specific load and rpm, +10 would add fuel and pull timing, -10would pull fuel and add timing. If your car runs best at +50 you have some serious issues you need to resolve. Is your modifcation list in your profile up to date?

Once you go negative you are adding fuel. SAFC's dont add timing. Your ecu might pull timing though if it sees knock

Okay these 2 posted replies are conflicting each other? My mods are up to date.

2gGSXEclipse is right, If you are negative you are adding fuel. So If you are on 550's your safc should be around -10 to - 15 not +50.

2gGSXEclipse said:

Once you go negative you are adding fuel. SAFC's dont add timing. Your ecu might pull timing though if it sees knock

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That is not correct, negative numbers on the SAFC will lower the amount of airflow the ecu is seeing, which in turn removes fuel and adds timing. Take a look at some fuel and timing maps. Lower load cells almost always have more ignition timing, when the safc tricks the ecu into seeing less airflow, fuel is removed and timing is advanced.

http://www.dsmtuners.com/forums/articles-tuning-ecu/366004-safc-tuning-how-why.html

Read the 9th paragraph to verify what i said, then read the whole thing to get an idea of how the safc works in conjunction with the ecu

Luke is correct.

The SAFC doesn't directly change timing. But since it alters the airflow signal to the ECU it makes the ECU "think" that the volume of air entering the engine is different from what it actually is. If the ECU "thinks" that the volume of air is more than what it actually is (+ adjustment on AFC) then the ECU might use a different timing map in effect pulling timing and vice versa.

Just think to yourself... + is adding fuel and - subtracting fuel....

Oh my goodness i don't know what is true? Please more people chime in here. Is + on the safc adding more fuel or taking away more fuel?

You need to listen to logic here. You can not add more air to your engine by simply adjusting AFC . You can only alter the signal the ecu receives. You tell the ecu more air is coming in than reality and you have a fuel enrichment because the ecu will try and match that air with extra fuel. So when you adjust in the + direction on your controller you tell the ecu hey more air is coming in... now whether that is true or not your ecu will adjust duty cycle on injectors to supply more fuel. adjusting in a - direction and you get the opposite.

Just read the information provided in the links until you understand.

http://www.dsmtuners.com/forums/articles-tuning-ecu/105569-how-safc-works.html

http://www.dsmtuners.com/forums/articles-tuning-ecu/58403-definitive-piggyback-tuning-guide.html

chanley talon said:

Oh my goodness i don't know what is true? Please more people chime in here. Is + on the safc adding more fuel or taking away more fuel?

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+ adds fuel and compensates for a lean condition.

- removes fuel and compensates for a rich condition, say, when you add larger injectors.


It's much more common to be in the "-" range if you have larger-than-stock injectors, except if you're a 1G car using a 2G MAS.

Because of the timing correction by airflow, it's better to make fine-tuning adjustments with an AFC than it is to max out the settings at 50% +/-. Your best bet is to have an EPROM chip burnt (if possible) to your fuel injector size, then do fine-tuning with the AFC, or even correct for injector size using a MAF Translator then fine-tuning with the AFC.

Well i tuned it last night on 20 psi no knock. My settings for the high side run +31 across. Also the low side seems to have a profound effect on it. I tuned the low side at +31 +31 +31 +27 +26 +25+22. Seems to work for now? It has a 2 gmas and it has 264/272 cams. I believe my injectors are really to small so i'm going to get some 650cc or bigger.

What kind of AFR's are you getting at WOT?

chanley talon said:

Well i tuned it last night on 20 psi no knock. My settings for the high side run +31 across. Also the low side seems to have a profound effect on it. I tuned the low side at +31 +31 +31 +27 +26 +25+22. Seems to work for now? It has a 2 gmas and it has 264/272 cams. I believe my injectors are really to small so i'm going to get some 650cc or bigger.

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Those number are whacked if you really have a untouched 2g MAF and 550's and a 1G.

steve said:

Those number are whacked if you really have a untouched 2g MAF and 550's and a 1G.

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Especialy the +31 across the board on the hi setting? Should vary from rpm to rpm correction point....

Is there a good tune shop around Nashville,Tn? I don't have a wide band so maybe i need one.

What logged info have you been using to tune with (eg-narrow band O2 voltage)?

A wideband will definitely make tuning much easier and reliable. You could use the money you would spend to have a shop tune the car for you to get a wideband.

Hey i don't use 02 voltage i just try to tune out knock with the safc . I'm getting some tax money back here's what i'm going to do. I'm buying a wide band 02 and i'm buying new plugs and wires and i'm going to get some 650cc injectors so i don't have to adjust much also. I have a Meth injection kit i have to figure when that needs to be kicked on as well. Needless to say the car is pretty frigen quick but i know its not right and it's killing me.
I think i better get the right tools and leave it alone for now.

As already mentioned, your numbers indicate that you are adding a lot of fuel and, if accurate, you should be running very rich. If that is the case then continuing to run the car can potentially cause accelerated wear of engine internals since the excess fuel will get into the oil and break it down. Have you noticed any signs of running rich? Eg-Smell fuel in the exhaust? Are the plugs black and smelling of gas? Puffs of black smoke out of exhaust when shifting?

Also keep in mind that you can get knock from running too rich. If you can log front O2 sensor voltage you can use that to get a rough tune until you get a wideband. Aim for .92-.94 volts during WOT and no knock. Lower voltage values indicate leaner conditions and vice versa.

i'm going to get some 650cc injectors so i don't have to adjust much also

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Figure out why your current adjustment values are so far off of expected values before you get larger injectors.

Yes i notice a rich smell when the safc is turned towards the _ area? Im going to do a log and post it.

Okay i found the problem. It seems that safc and the chipped and tuned ecu don't like each other. I unhooked the safc and wired the ecu back up to control things and man did it help instantly. The ecu has been tuned for the target airflow of 11.1 afr . It also has had the timing maps tuned down because i have 2g pistons. Needless to say the knock i had vanished and there was a big top end power gain.
So now i think i will put my timing back to stock 5 btdc. I had it set to 0 of course it adds 3 degrees back.

If your ECU is already compensating for the 2g MAS, and set for your size injectors, then the SAFC should be set at zero across the board. Do you have the settings for your chip?

A log would make things much easier.

I found the problem it is the ecu! The safc is good. Some how the ecu circut that is running the air flow sensor is not working. What i did is swapped in a new ecu that i borrowed and wall la fixed. I want to report back and let everyone know the problem.

chanley talon said:

I found the problem it is the ecu! The safc is good. Some how the ecu circut that is running the air flow sensor is not working. What i did is swapped in a new ecu that i borrowed and wall la fixed. I want to report back and let everyone know the problem.

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Do yourself a favor and at minimum get a palm pilot, MMCD, Logging cable. These can all be found very cheaply on ebay or the classified on this sight. I'd bet your fuel trims are horribly off.

*Edit* Just noticed your TMO logger. What are the fuel trims at?