Baro Presssure Max/Min

[HPLouis]

What does this do for our cars? Common practice for blown cars is to put both at 27 to shut it off but I've seen some tunes where they modify it from 21 Min and 30.5 Max to 27 Min and leave the Max at 30 or they just leave it stock.

Does anyone know why the different settings? What happens if you just turn it off?

Thanks

 

[decipha]

This might stem back from the fox body days. The foxes have an actual bap sensor which some people mistakenly hook up to manifold reference since the older speed density ecu's used the same exact sensor but to manifold pressure for map instead of to atmosphere for bap. The problem that caused was that at WOT manifold vac would drop and BAP would go to full altitude causing the wot spark modifier to dump in 12 degrees of timing and cause engine problems.

After the foxes almost all fords use inferred baro pressure based on the difference between actual load and inferred load (TOTLDST).

If its off quite a bit then it assumes its due to altitude since barometric pressure would affect the airflow which is how load is calculated.

The problem tuners run in to is that they don't dial in inferred load so inferred bap can go ape shit and cause drive-ability issues.

Up until about 5 years ago it wasn't possible to dial in inferred load since OBD-2 logging is too slow and none of the commercial software had access or the ability to setup histograms to dial it in properly.

This is one of the major benefits of tunerpro using the moates quarterhose as it automatically populates the inferred load histogram for you. You simply drive and it requires no user input so the software actual tells you how far off you are and gives you the actual correction percentage to get it perfectly dialed in. The added benefit is that inferred load is also used for anticipated airmass which is a transient fuel feed forward correction. You'll notice the engine runs smoother when its dialed in properly and fueling is more consistent.

Another side annotation to inferred bap is that the isc duty cycle code uses the same FN095 ACT temperature compensation for correcting the isc duty cycle based on altitude. So if inferred bap goes too far off it can actually affect idle too. My custom target iscdc code was affected by this too til I found it in fbgi0 since it has specific isc pid bypass code I hadn't seen in any other strategy.

In any case I have found the best option is to just dial in inferred load. I clip minimum inferred bap to 29.875 in all my tunes as an additional safety just so if something goes off or isn't functioning correctly its safer.

 

[HPLouis]

This might stem back from the fox body days. The foxes have an actual bap sensor which some people mistakenly hook up to manifold reference since the older speed density ecu's used the same exact sensor but to manifold pressure for map instead of to atmosphere for bap. The problem that caused was that at WOT manifold vac would drop and BAP would go to full altitude causing the wot spark modifier to dump in 12 degrees of timing and cause engine problems.

After the foxes almost all fords use inferred baro pressure based on the difference between actual load and inferred load (TOTLDST).

If its off quite a bit then it assumes its due to altitude since barometric pressure would affect the airflow which is how load is calculated.

The problem tuners run in to is that they don't dial in inferred load so inferred bap can go ape shit and cause drive-ability issues.

Up until about 5 years ago it wasn't possible to dial in inferred load since OBD-2 logging is too slow and none of the commercial software had access or the ability to setup histograms to dial it in properly.

This is one of the major benefits of tunerpro using the moates quarterhose as it automatically populates the inferred load histogram for you. You simply drive and it requires no user input so the software actual tells you how far off you are and gives you the actual correction percentage to get it perfectly dialed in. The added benefit is that inferred load is also used for anticipated airmass which is a transient fuel feed forward correction. You'll notice the engine runs smoother when its dialed in properly and fueling is more consistent.

Another side annotation to inferred bap is that the isc duty cycle code uses the same FN095 ACT temperature compensation for correcting the isc duty cycle based on altitude. So if inferred bap goes too far off it can actually affect idle too. My custom target iscdc code was affected by this too til I found it in fbgi0 since it has specific isc pid bypass code I hadn't seen in any other strategy.

In any case I have found the best option is to just dial in inferred load. I clip minimum inferred bap to 29.875 in all my tunes as an additional safety just so if something goes off or isn't functioning correctly its safer.

Thank you so much for the detailed and informative post. I really appreciate it.