Adj MAF for Boost?
05-04-2006, 09:25 AM
#22
Originally Posted by WAHUSKER
This must be the real reason why they run in SD mode.....I just don't want to because of all the fiddling you have to do whenever the conditions change. I want to tune it in & forget it.
you seem to be under the impression that SD EFI doesnt adapt.
actually, speed density has been used long before MAFs were common on any cars.. and even a few new cars still dont have MAFs..
matter of fact, when you get down into it SD in alot of aspects is MORE accurate.. obviously you cant say one is more accurate then the other overall, but it all depends on your preferred way of indirectly measuring in the incoming air.
the MAP sensor is a ABSOLUTE pressure sensor.. so it can tell if you're at sea level, or at the top of the rockys. no re-tuning for pressure unless you didnt tune a area because you cant drive in it.
for example, i normally drive between 3 ft below sea level to 10ft above it.. its low and flat here. so while i can fill out my 100kpa and 105 rows easily at WOT, theres a "hole" in my tune above that in the table where im just guessing.. because honestly, i cant hold it in the 80 or 85 range there easily..
the IAT sensor tells you the air temp.
so if you know the temp of the air.
and the pressure of it...
and lookup how efficient the motor is at getting air into it at that instant (the "VE")
you can figure out exactly how much is going into each cyl.
and when it rains, with cold air and a low pressure storm above ya... it compensates. whatever the condition it compensates.
if it doesnt, you have something wrong with your tune.
honestly, id prefer a highly accurate and reliable MAP sensor over a finicky MAF sensor anyday... notice the engine will work without the MAF... but not without the MAP..
