RAF and Effective area, will changing one effect the other?
05-27-2005, 01:58 PM
#1
RAF and Effective area, will changing one effect the other? ok so i went and logged my desired idle airflow vs my dynamic airflow. they were very far off so what i did was take the IAC steps and moved them in the effective area table and built another curve. i notice my ltit and stit getting closer to zero
now my question is, will calibrating the effective area table like this mean i dont need to adjust the RAF table? how do i determine the RAF table, if it is off will the ltit and stit read different reguardless of the IAC effective area table?
pretty much, does the raf just have to do with the trims?
and does the effective area just have to do with the offset of the desired and actual airflow?
now my question is, will calibrating the effective area table like this mean i dont need to adjust the RAF table? how do i determine the RAF table, if it is off will the ltit and stit read different reguardless of the IAC effective area table?
pretty much, does the raf just have to do with the trims?
and does the effective area just have to do with the offset of the desired and actual airflow?
05-27-2005, 03:58 PM
#2
RAF has to do with keeping the engine running.........
it goes this way:
1) an engine with a CI/cam/head/header/etc. will need "X" amount of air to run at some RPM........
2) the RAF table holds this info so the computer can look up HOW MUCH air is needed
3) the computer will look at the IAC effective area table to find out how much it needs to open the IAC motor out to give the required ("X") air needed (too much air = over RPM....too little = under RPM.......thus why if either of these tables are off the engine will act up........the computer can make small adjustments but they take time.......)
4) now that the computer knows how much air should be let in, it will look at the MAF (if there) and VE (compares the MAF to VE) to see that the engine is getting the flow required and now provide the required fuel to match
4.1) if no MAF then the computer will look at the VE table only to find out required fuel
5) fuel and air burns
6) computer looks at O2s to see how far off the air fuel tune was off and adjusts the Ltrims (which are fuel only......the computer can not "add air" to the mix)
it goes this way:
1) an engine with a CI/cam/head/header/etc. will need "X" amount of air to run at some RPM........
2) the RAF table holds this info so the computer can look up HOW MUCH air is needed
3) the computer will look at the IAC effective area table to find out how much it needs to open the IAC motor out to give the required ("X") air needed (too much air = over RPM....too little = under RPM.......thus why if either of these tables are off the engine will act up........the computer can make small adjustments but they take time.......)
4) now that the computer knows how much air should be let in, it will look at the MAF (if there) and VE (compares the MAF to VE) to see that the engine is getting the flow required and now provide the required fuel to match
4.1) if no MAF then the computer will look at the VE table only to find out required fuel
5) fuel and air burns
6) computer looks at O2s to see how far off the air fuel tune was off and adjusts the Ltrims (which are fuel only......the computer can not "add air" to the mix)
