If the MAF senses airflow into the eng, why would I need to burn a chip if I perform airflow mods(porting, headers,cat-back, etc)?
It seems like the MAF should see the increased airflow and adjust the injectors accordingly. What am I missing?
Does the chip limit the extra amount of fuel that can be delivered?
Probably a stupid question, but I'm new to TPI.

 

The maf does see the increased airflow, but the computer can only compensate so much from it's base programming, so major changes require reprogramming, while minor ones don't.

 

Indeed the MAF directly measures air flow (volume) into the engine. The amount (mass) of fuel required under varrying engine conditions depends on air flow, air temperature, engine temp, throttle position, load, and other parameters.

The ECM uses these parameters to index into a stored table to determine the injector pulse width. It is this stored (in EPROM within the CalPac) lookup table that is subject to reporgramming.

At part throttle, in Closed Loop mode, the ECM uses O2 sensor readings to adjust or "trim" the injector pulse width in real time. If you increase air flow by say modifying the exhaust sysetm you will observe on a scan tool that the "trim" values will change from prior values. At WOT, in Open Loop mode, the ECM ignores the O2 sensor values so cannot "trim" pulse width to match air flow.

This is why we reprogram the "chip" or adjust an AFPR. Also the "chip" can be prograrmmed to change ignition timing to attain optimum power as well as modify TCC lockup point and coolant fan On/Off points.