420A SAFC and 420a

[96 420a-t]

So I have seen that the SAFC doesn't let you tune while in boost. Is this because of the FCD (missing link) that we have to install to use boost in the first place?

 

[95talongirl]

SAFC is not a good tool for the 420A cars. The reason is the SAFC utilizes a MAF sensor for inputs. The 420A cars run a MAP (aka speed density setup.) A MAF sensor works by reading the volume of incoming air and changes fuel demand based on the actual volume, whereas a speed density setup uses Manifold pressure, air temperature, throttle position, and vacuum to determine the air flow and then has a computer algorithm to determine how much fuel is needed. Because of this difference in how the two systems receive their air flow system, the SAFC, which is dependent on the MAF signal will not accurately "know how" to handle the various inputs of the Speed density system. This is why a SAFC is not ideal for the 420A cars.

oh yeah... and on a N/A car the MAP sensor doesn't recognize positive pressure, so you'll have to get a different MAP sensor; which is what I think a FCD emulates.

 

[VelocitàPaola]

oh yeah... and on a N/A car the MAP sensor doesn't recognize positive pressure, so you'll have to get a different MAP sensor; which is what I think a FCD emulates.

Close, but you don't need a new MAP sensor. The FCD prevents the one you have from reading above 0psi and sending the car's control system into a panic mode.

 

[95talongirl]

ok, cool. I just know in the turbo dodge world, everyone liked to run 3 bar MAP's... but thats on a system already setup to recognize positive pressure. Thanks for the clarification!

 

[96 420a-t]

From what I have seen the SAFC can run in a pressure mode as well. Even though it is not as good. So if I were to get larger injectors what would I use besides DSMLink to tune in boost?

I was thinking that if you put the SAFC in pressure setting and wire in a 3 bar map for the SAFC. The SAFC manual is a long one so I'm not 100% on it.

 

[Carter_95RS]

Megasquirt.

Link is for the 4g guys.

 

[96 420a-t]

I was trying to avoid going with a standalone type system.

 

[95talongirl]

yeah, the dsmlink would be cool.... but you guys run a chrysler electronic system and AFAIK cannot be socketed like the mitsu eprom ecu can.

The SAFC can run seeing pressure; my point was it interrupts the MAF signal. The chrysler varients do not run a MAF sensor... this is why the SAFC doesn't work as well on those applications.

 

[96 420a-t]

I have seen them installed and working on hondasoften, and they don't have a maf.

 

[96TurboGS]

Most stock Honda sensors can read up to a max of 10 PSI and doesn't cut fuel at 101 kPa. Anyways, Megasquirt would only be mandatory if you're aiming over 300chp. (IMO) Bigger injectors and a SAFC w/ adjustable regulator, map clamp could be used but the downside is its costly and idle fuel pressures are low, but it works. If not, the 12:1 FMU has worked well for many over the years. (Not the most accurate but again, it works) Also, SAFC could mess with the timing in the PCM; margin of error gets larger as you add PSIg.

 

[95talongirl]

I'm not saying that it won't work..... it just doesn't work as well as it should or could. There's more of a margin for error, as stated above; since it is trying to run off a system for air/fuel control it was not designed for.

And if you are not aiming for high horsepower levels, then this could be fine. Personally I like to be able to control things as best as possible.

 

[tec_41]

Speaking from experience...

I ran one just out of curiosity on my 95 esi-t. At idle you can make your adjustments and it seems like it's working. Then you do a pull and everything pretty much resets itself, as if the ECU is compensating for what the SAFC is changing. So you add more fuel, do a pull, and it goes back yet again to where you started. They just won't work unfortunately.

I know a lot of guys are quick to jump on the "it won't work" bandwagon, but I actually know from experience

 

[96TurboGS]

I've ran the FMU and the SFMU w/ SAFC many years before running MS several years. The SAFC is useless if you have a 12:1 w/ stock or slightly upgraded injectors. I used one to keep me from burning out my O2 @ idle and cruise to obtain good gas mileage but it does work fine with a SFMU. (Not mandatory though) Upgraded cams will affect how big (CC) you can go on injectors without having a rich idle.

So you add more fuel, do a pull, and it goes back yet again to where you started. They just won't work unfortunately.

You can't add fuel with the SAFC. The PCM will open the injectors to its maximum PW while your regulator steps up the pressure from the vac source in boost. You only can subtract fuel to a extent.