Tuned as a 2 bar MAP but is actually a 3 bar

[barbermi]

Hi all,

I have been having troubles starting my supercharged LS1 since day dot and i think i may have worked out what the issue is.
The car was tuned by a guru and i think the MAP sensor may have been overlooked.
Overall i am very happy with the tune (480rwhp) but the car doesnt start without touching the throttle pedal and sometimes wont start at all if hot!
I looked at a few things and found the MAP was reading ~40kPa without the engine running. This should be at around 101kPa as per the manual etc.

I have a sneaky suspicion the car has had a tune with the wrong MAP scaler in it hence making it hard to start.
I want to set it right and put the MAP scaler {C6301} to a 3 bar setting =288 but i am worried if i do it will ruin the entire tune.
Are my fears correct? If i make a change to the scaler so that the MAP reads 101kPa without the engine running instead of ~40kPa it currently reads will it mean i will have to re-tune the entire fuel map again?

Thanks

Mark

[joeygc5]

When you reset the MAP scaler value you'll need to rework the VE and probably the timing tables as well.

[joecar]

By changing the MAP scaler you are now changing the indexing into the columns in the VE and OLFA tables...

a retune is safer than mathematically shifting/expanding the columns in the VE tables.