I only boost 6psi, and EvoScan logs up to about 33.3 when I hit 5-6psi or so...but I don't know what that actually means. I'm logging JDM MAP with the proper atmospheric pressure, and I am hoping that since I don't boost like you guys, that I can get away with just using the stock MAP.

My goals are the following:

1. determine when the car hits "positive pressure" or when the car is in boost

2. Log exactly what boost is throughout a pull

2 is less important than 1, but I don't know how to interpret the numbers being given to me by evoscan. The formula I have is 0.19347*x-14.3 and that's supposed to be in psig, which I would expect to be "6" (but I see ~33) since that's what my boost gauge says. Thoughts?

Oh, and the lowest thing I log is about -4...which I would expect to be something like, -22 since that's the min I typically see on my gauge at idle, maybe lower if I "engine brake".

 

If I remember right the stock map sensor will barely read over a few psi. You will need to atleast buy a 3bar or 4bar map sensor. If you buy the Omni power 3/4 map sensor it is just a bolt in affair and then you just have to add some tables to your rom. Its pretty easy, Id say it would take around a half hour to do everything.

 

You say "stock" but you also say "JDM". If your Evo is USDM then your stock map sensor is not JDM. If you are using a JDM sensor then you can log up to almost 30psi IIRC. I'm not the man to be telling you if your scaling is correct or not though.

 

By the way if you indeed don't have a JDM map sensor you can get an Evo X map sensor from a stealership and use that. Same thing from what I understand. Or Omni Power has 4 and 5 Bar sensors.

 

The formula is correct, but you will not be able to LOG over 2.2psi with the stock(USDM) map sensor...

You should be able to find a JDM map sensor(3bar) on the evo for sale thread or just get one new at mitsubishiparts.net...

hope this helps...

 

Thank you for the input, as far as "JDM" what I mean is logging that output in EvoScan, which really just means taking the value of the MAP sensor I think and subtracting 14.3 (or whatever atmospheric pressure is). I understand that I may only be able to log 2.2psi, but that would be plenty for me. All I really need to know is when the car hits "positive pressure" for tuning purposes. My question is, even if I can only log a small number of psi, what do the numbers I am logging right now mean? They don't stop at a certain ceiling, they continue to go up as I press harder on the accelerator....but I just don't know how to interpret them.

 

what numbers are you talking about? be more specific... send me a pm if u want

 

The numbers in my first post,

logs from evoscan show -4 to 33
boost gauge shows -22 to 6

formula used is the one in the first post. Any correlation there? all I can figure the first is -22 + 18 = -4 and 6 + 18 = 24....so it's not a linear difference

 

To get an accurate representation of boost you are going to need atleast a map sensor that reads at least the amount of boost you are going to run. You can get a 2 bar map sensor for 50 bucks and Im sure someone has the scalings for it on here somewhere.
In my opinion this is going to be the only way to get your fuel and timing correct without guessing.