Bigger Fmic And Afr's?

ACRucrazy · 02-07-2004

Sorry for the newbie question but here it goes.

Now say you put a bigger, better FMIC on a vehicle, how much does that change the AFR?

I look at it in 2 ways,
1- the air that the turbo pushes through the IC should be the same about at the same boost setting no?
2-but that same amount will get cooler, so denser... so it would be leaner??

Am I right about this?
Thanks :jammin:

CVD · 02-07-2004

If your ECU has any idea what it is doing, and your fuel pump/injectors are big enough, then it should have no effect on the A/F ratio.

**Shane@DBPerformance** · 02-07-2004

It all depends on what the stock ECU is programmed to do and how it actually meters airflow. If you car uses a MAF/MAS that is located before the intercooler then the car will probably go a bit leaner with better intercooling. If your car uses a speed density(MAP) setup and the air temp sensor is located after the intercooler, like in the intake manifold, then it should do a better job of adjusting the fueling for cooler air, but it might overcompensate and go too rich. If the AIT sensor is before the intercooler or turbo then it should run leaner.

ACRucrazy · 02-07-2004

Well, it has the Stage 1 PCM and bigger injectors.
It has a Map sensor and Tip sensor that work together, kinda wierd, never had to deal with a TIP sensor before.
It made sense, so yes theyre will be denser (more) air goin in, but the Map "should" tell the pcm-injectors to compensate for it.
Thanks!

AGP here I come

**Shane@DBPerformance** · 02-07-2004

Well, the MAP sensor will only tell the ECU the boost level. You usually need an air temp sensor to be used in conjuction with a MAP sensor for the ECU to figure out fueling. Cooling air also causes a loss in pressure as part of the cooling process. An intercooler that exhibits no pressure drop isn't doing crap. Your boost control level could also change depending on where your getting your boost source from, it it's sources post intercooler then it should stay the same, if it's pre-intercooler like off the turbo comp housing then you might actually see less boost in the I/C cools the air a lot more than previously.

What is a TIP sensor do?