tnt76
New Member
- Messages
- 11
- Location
- Portland, Australia
Fastegg, I have made a couple of assumptions and I hope you dont take this the wrong way, but I think you need to study the whole EFI structure, including the ignition mapping side of both factory and aftermarket setups.
For example, the ignition timing advance in an ECU controlled vehicle are more than just advance vs rpm where traditionally the timing advance would start at a set figure, say 12 degrees at idle and slowly ramp up to a predetermined max of say 36 degrees (typical chev) by around 3000rpm and then sit at that until full revs.
In EFI that timing can do that, plus more, eg. have an idle timing of 12, ramp up to 30 + before peak torque(3000), reduce down to 27 at peak torque(4500) and then ramp up to 36 at peak hp(6000+), then throw in a load sensor (MAP, MAF or just TPS) to tell the ECU that it isn't at full throttle (high vacuum), in which the timing advance can go to 40+ at cruise (1500-2500) where normally it would be around 20ish. So it's a 3d map. Then there's the corrections like coolant temp and air temp corrections, which turn the spark map 4,5or 6 dimensions.
Same for the fueling side.
If I were you, I would get your OBD going and study what is going on in the factory ecu and watch how things change in different conditions and go from there.
Also go and download some of the free software for the aftermarket ECUs and flick through all the different maps and get an idea of how everything comes together to supply that certain spark advance figure or injector pulse width.
For example, the ignition timing advance in an ECU controlled vehicle are more than just advance vs rpm where traditionally the timing advance would start at a set figure, say 12 degrees at idle and slowly ramp up to a predetermined max of say 36 degrees (typical chev) by around 3000rpm and then sit at that until full revs.
In EFI that timing can do that, plus more, eg. have an idle timing of 12, ramp up to 30 + before peak torque(3000), reduce down to 27 at peak torque(4500) and then ramp up to 36 at peak hp(6000+), then throw in a load sensor (MAP, MAF or just TPS) to tell the ECU that it isn't at full throttle (high vacuum), in which the timing advance can go to 40+ at cruise (1500-2500) where normally it would be around 20ish. So it's a 3d map. Then there's the corrections like coolant temp and air temp corrections, which turn the spark map 4,5or 6 dimensions.
Same for the fueling side.
If I were you, I would get your OBD going and study what is going on in the factory ecu and watch how things change in different conditions and go from there.
Also go and download some of the free software for the aftermarket ECUs and flick through all the different maps and get an idea of how everything comes together to supply that certain spark advance figure or injector pulse width.
