MAP Sensor questions

[2000Falcon]

Bare with me here guys, because I did do a search.

I have a few quick questions regarding the MAP sensor functions and what it controls on our boosted cars (SC Grand Prix's, 3800's).


1- When exactly is the MAP used for fuelling (open/closed loop, or only in VE/MAF fail mode)?

2- Does the MAP control anything in OPEN LOOP? Understand MAF controls fuelling in open loop when functional. (I have been MAF scaling for fuelling until now)

3- When DTC P0107 (Manifold Absolute Pressure/Barometric Pressure Circuit Low Input) is detected, how may this MAP Low Voltage affect fuelling at idle and at WOT. What sort of symptoms would one expect to encounter?

Thanks so much in advance.

[oakleafresin]

I can't provide a definitive answer to your questions but I know this:

According to Gary from Holland Motorsports (the GOD of tuning for 3800's),

"This guide will address VE tuning, in SD mode. Although some may argue the validity, the VE table is not referenced only in the event of a MAF failure. It is referenced in nearly all airflow, fueling, and calculations. If you choose to pass over this section your tune may not be correct."

That is why the VE table is so important to be accurate. I will also tell you this, using the guide written by Gary here http://www.hollandms.com/newbie/tuning_new.htm, I had gotten my LTFT's to close to zero with the MAF unplugged and the second I plugged the MAF back in WOW, car drove completely different (much better). So it definitely effects the power output even with the MAF plugged in. Sorry for the essay.