Chrysler to continue using MAP sensors

[GMBoy]

Originally Posted By: brianl703
I think that throttle position sensor in conjunction with a MAF more than compensates for the slower response of a MAF.

At least it does on Ford vehicles, which have used MAF setups exclusively for about 15 years now. The newer Ford vehicles which use a MAF also do not have a BAP (baro) sensor. Some of the old ones did have both a MAF and a BAP sensor, but they now use the MAF readings to calculate a BARO reading. (I've never seen any documentation as to how this is done).

The BARO reading on these Ford vehicles can be used to determine if the MAF is reading correctly. An incorrect BARO reading is an indication that the MAF is not right.



The throttle position sensor just tells the PCM how much you are pressing on the gas whereas the MAF and MAP are calculating air volume. TPS is not related to the MAF or MAP.

 

[brianl703]

I know what the TPS does. I also know that the TPS can respond instantly to what the driver's foot is doing (well, not quite instantly---depends on how fast the PCM is sampling that reading) so that TPS readings can and are used by the PCM (at least on Ford vehicles) to compensate for any delay in the reading from the MAF that would occur as you open the throttle. This is the accelerator pump function in software. The software can also calculate what the expected MAF reading is for a given throttle position. If the actual MAF reading does not agree with what is calcuated, a code is set.


When I changed out my 1988 Mustang GT from MAP to MAF, there was an improvement in throttle response. Since I had to change out the PCM at the same time, I expect some of that improvement is due to improved software.

Note that Ford vehicles do NOT use both MAP and MAF sensors.

 

[mechanicx]

I do agree that MAF is slightly more accurate than MAP (speed density), especially during steady operation and in open loop. The MAP doesn't actually measure air mass like MAF does, so it is making an assumption/extrapolation of actual mass. MAF even without B/MAP is probably just as accurate or more in transitions as speed density. MAF with a MAP as GM uses probably adds an extra layer of precision, but as you pointed out software and ST/LT fuel trim is equalizing factors.

 

[GMBoy]

Originally Posted By: brianl703
I know what the TPS does. I also know that the TPS can respond instantly to what the driver's foot is doing (well, not quite instantly---depends on how fast the PCM is sampling that reading) so that TPS readings can and are used by the PCM (at least on Ford vehicles) to compensate for any delay in the reading from the MAF that would occur as you open the throttle. This is the accelerator pump function in software. The software can also calculate what the expected MAF reading is for a given throttle position. If the actual MAF reading does not agree with what is calcuated, a code is set.


When I changed out my 1988 Mustang GT from MAP to MAF, there was an improvement in throttle response. Since I had to change out the PCM at the same time, I expect some of that improvement is due to improved software.

Note that Ford vehicles do NOT use both MAP and MAF sensors.


I see your point.