Differences in MAF and MAP tuning
 

Alright I am trying to figure something out. On my car (98 Cavalier) If i "wanted" to use a SAFC ( I am not, i'm running on megasquirt just using it as an example) I would still need a FMU, to raise the fuel pressure with boost, since the SAFC could not control the fuel enough. My car has a MAP sensor, that is not supposed to see boost. First am I right in Thinking this way.

Second with a car with MAF would it technicaly need a FMU to read the boost and raise the fuel pressure, or will the sensor read the amount of air and add adequate fuel, allowing you to use a AFC w/o a FMU?

Re: Differences in MAF and MAP tuning
 

your thinking TOO outside the box ryanizzle. you wouldn't need the fmu becuase you control how much fuel the injectors throw in w/ the safc. w/ the map sensor thing, it's not supposed to see boost when it's stock. when you use the safc, it alters the readings goin to the map sensor so it acts like the boost isn't there. same thing w/ the maf. the maf doesn't control how much fuel goes in, the injectors do. hence the need for wideband tuning. just gimme a call sometime and i can help ya w/ dis shiznit man!!!

Re: Differences in MAF and MAP tuning
 

the way i was seeing it is the SAFC can only control fuel +/- 50% and its rpm related. so say i get on the gas, get in boost from 2000 rpms+ extra fuel would be needed to run safe/right (obviously) but if i wanted to cruze out of boost which my car does at about 2500rpm's at 60mph, the SAFC would still see the 2500rpms and making the car run super rich, Now if you run a FMU and a SAFC, the car runs like normal until it see's boost then the SAFC is for fine tuning.

Now alot of people run just a SAFC without a FMU on MAF, doesn't the MAF "read" how much air is going to the engine and responds by injecting more fuel?

Re: Differences in MAF and MAP tuning
 

the afc is not adding the same amount of fuel at all map readings (like you said, 2500 rpm in boost or cruising)...its is only implementing a correction factor for the stock fuel/timing tables at that point (rpm and map reading). And yes, up to a certain point a stock maf will read the increase in air and add more fuel

Re: Differences in MAF and MAP tuning
 

ok i guess i was just seeing the afc control fuel by rpm, i guess i didn't realize it's adjusted by MAP reading also. which makes sence now.