ForScan Lite PID

[Ta2dResqr]

I am trying to use ForScan Lite to see how much my car is boosting. I have enabled the MAP PID. This is showing 5 psi at idle, 26.2 psi at WOT, and 29.7 psi spike on shift. Is there a way to interpret this to determine my boost? Is there another PID I should be using?

 

[Ecoboost_xsport]

I am trying to use ForScan Lite to see how much my car is boosting. I have enabled the MAP PID. This is showing 5 psi at idle, 26.2 psi at WOT, and 29.7 psi spike on shift. Is there a way to interpret this to determine my boost? Is there another PID I should be using?

Subtract 14.7

MAP is absolute pressure, which includes 1 standard atmosphere, which is approximately 14.7 psi, depending on your location.

 

[Ta2dResqr]

Subtract 14.7

MAP is absolute pressure, which includes 1 standard atmosphere, which is approximately 14.7 psi

So approximately 11.5 psi? Is that fairly conservative?

 

[Ecoboost_xsport]

So approximately 11.5 psi? Is that fairly conservative?

Yes, pretty much stock boost, IIRC

 

[yaycandy]

Subtract 14.7

MAP is absolute pressure, which includes 1 standard atmosphere, which is approximately 14.7 psi

Yea i always forget to minus erf

 

[Ecoboost_xsport]

If you had a way to datalog like with SCT or HPT, there is a DMR called Boost In PSI (if your strategy supports it) that can tell you (wait for it)...boost...in...PSI (LOL), but MAP is actually more accurate since it's the direct reading from the sensor. Some PIDs are not from sensors directly but either calculated or inferred based of other sensors. You'll just have to remember to subtract 14.7 all the time.

Or, again, if you had SCT or HPT, you could create some User Defined PIDs with formulas that you can datalog in real-time. It's how I recently start datalogging Boost Air Density (estimated since our vehicles, as most, don't have a Relative Humidity sensor), calculated using MAP, Ambient Air Temp, Intake Air Temp2 and Barometric Pressure

 

[Ecoboost_xsport]

Oh, and if you're looking for a pretty decent customizable gauge suite, check out Torque Pro. Not really ideal for datalogging (although you can datalog and save data in .csv spreadsheets), but if you set it up right in your vehicle, you can use it instead of a number of gauges...

It's what I did here:
https://shoforum.com/index.php?thre...maintenance-thread.142193/page-2#post-1553649

 

[stripSHO]

If you had a way to datalog like with SCT or HPT, there is a DMR called Boost In PSI (if your strategy supports it) that can tell you (wait for it)...boost...in...PSI (LOL), but MAP is actually more accurate since it's the direct reading from the sensor. Some PIDs are not from sensors directly but either calculated or inferred based of other sensors. You'll just have to remember to subtract 14.7 all the time.

A small correction if I may... you want to subtract the uncorrected barometric pressure for your location to find gauge boost. Someone in Colorado might only subtract 12 psi. But I personally haven’t logged boost in like a year. Manifold Absolute Pressure is what really matters, and much unlike boost it means the same thing at sea level as it does at the top of Mount Crumpit.

 

[Ecoboost_xsport]

A small correction if I may... you want to subtract the uncorrected barometric pressure for your location to find gauge boost. Someone in Colorado might only subtract 12 psi. But I personally haven’t logged boost in like a year. Manifold Absolute Pressure is what really matters, and much unlike boost it means the same thing at sea level as it does at the top of Mount Crumpit.

Yes...the 14.7 value is very, very approximate. Lots of other variables involved. I also like MAP better but knowing "boost" for purposes of general info and conversation isn't a bad thing. It's a value most of us have used and are more familiar with. I've actually been trying to use Boost Air Density for a reference on modification improvements recently and understanding how that may be more accurate in comparing before and after. But even that isn't 100% accurate without real-time Relative Humidity values to throw into the math.