IIRC, the stock MAF does not have the ability to compensate for the temperature of the air going through it (i.e. it is not "internally temperature compensated"). That is why GM put the IAT sensor near the MAF. If you look in the code of a stock chip, you will see that there are very large tables that are used to adjust the reading from the stock MAF to a "corrected" value depending on the IAT reading. So, a stock chip reading a stock MAF will look for the IAT reading to create a corrected MAF reading for fueling purposes.
Those tables take up a lot of the available space in the stock code in the chip. Therefore, many chip makers eliminate those tables and use the space for code for other features. Even if the chip maker does nothing with the IAT reading and just takes the raw MAF reading with no correction, well, it seems to be close enough. The BLM's might move around a bit more as the intake air temperature changes, but that would probably be the only drawback.
The more modern MAF's (LT1, LS1, etc.) are internally temperature compensated, so there is no need for an IAT reading. Chips that are designed to work with MAF translators usually do nothing with the IAT reading other than feed it out to the data stream so it can be displayed. Fueling, spark advance, etc. are not affected at all by the IAT reading when these MAF's and chips are used.
At the next level of technology, which is MAFless (such as with a MAFTPro), the IAT reading is absolutely required. Air mass flow is determined based on the engine speed, MAP reading, and IAT reading (a.k.a. "speed-density"). In this case, it is usually a good idea to put the IAT somewhere close to the engine so that it is reading the temperature of the air going into the cylinders. This usually means the up-pipe or the intake manifold.
Hope this helps...
Those tables take up a lot of the available space in the stock code in the chip. Therefore, many chip makers eliminate those tables and use the space for code for other features. Even if the chip maker does nothing with the IAT reading and just takes the raw MAF reading with no correction, well, it seems to be close enough. The BLM's might move around a bit more as the intake air temperature changes, but that would probably be the only drawback.
The more modern MAF's (LT1, LS1, etc.) are internally temperature compensated, so there is no need for an IAT reading. Chips that are designed to work with MAF translators usually do nothing with the IAT reading other than feed it out to the data stream so it can be displayed. Fueling, spark advance, etc. are not affected at all by the IAT reading when these MAF's and chips are used.
At the next level of technology, which is MAFless (such as with a MAFTPro), the IAT reading is absolutely required. Air mass flow is determined based on the engine speed, MAP reading, and IAT reading (a.k.a. "speed-density"). In this case, it is usually a good idea to put the IAT somewhere close to the engine so that it is reading the temperature of the air going into the cylinders. This usually means the up-pipe or the intake manifold.
Hope this helps...
