But doesn't the TPS factor in this equation?

I mean if the PCM sees the TPS at WOT, yet the volume of air is reduced by 20% or 30%, would that not throw calibration of the MAF, as the PCM reads it, out of whack?

This is a typical problem in this series. I find it odd that many of us have an identical issue, all unrelated to the restrictor plate.

I appreciate your input.

 

If your MAF is working correctly, then the PCM uses it to measure airflow - TPS is not used for fueling calculations.

Volume airflow reduction = mass airflow reduction, which the MAF is sensitive to - as long as the MAF is working properly, the PCM knows how much air is entering the throttle body.

 

A v6 maf is smaller. I know because I purchased a stock maf from someone one the board here and they ripped me off and sent me a v6 one. its about 1/4" smaller, i beleive. If you search my name and maf then you should find a thread I started when I wasn't sure what the particular maf was.

 

Same thing happened to me from a board member on here. You almost have to request that they measure the thing and post a pic to ensure you are getting the right thing.

 

The PCM uses the TPS position to determine when to switch from stoichiometric (14.7:1) closed loop A/F ratio to the PE mode calculated target A/F ratio (typically around 11.7:1 with stock programming). Once that happens, the PCM uses the MAF signal to determine the air flow, and uses the target A/F ratio to calculate the fuel requirement. Running a restrictor plate should not affect anything, other than limiting mass air flow.

The problem is that the stock programming PE mode "target" A/F ratio is too rich. That is the first thing a programmer will change, and its worth 10-15HP on a stock engine. Its only logical that you would find it running rich at WOT. This is one case where the Granatelli MAF sensor might actually make little bit of sense. It intentionally under-reports mass air flow rate at high flows, and may (if you are lucky) lean it out at the top end/PE mode, where there is no use of the O2 sensor data to correct the fueling. Normally, the Granatelli is a poor choice, when you can simply adjust the PE tables and lean the stock programming out, but if you are running under rules that absolutely prohibit any type of changes to the stock program, "fooling" the PCM may be your only recourse.