the.hamburglar

so iv been out the last few days tweaking my car and im noticing that my boost guage is showing 10psi positive pressure and when datalogging im getting about 7.5psi at the map sensor that was logged with my laptop. the ecu is using those values of 23.25 ign timing when the motor is really seeing 10psi where timing should be around 21.5. so overall it is 2* more advanced than i like it. why is my map sensor reading a differnt value that my nice boost guage? which one should i trust? id like to trust my map sensor but my boost gauge was realy expensive and id like to understand why they are out so much from each other

mrx

You can't trust both of them until you have some exact mesaurements with some high accurate reference pressure meter or something like this.

Sensor Power supply plays also a role, i don't think the stock 5v reference voltage is 100% stable over all engine operation conditions...

so you have a ton of factors playing a role when reading the map sensor.

i've thought about that too, but don't found a solution for this until now.
but i know and thats a fact: wherever you measure something you measure not only the value, you also measure x amount of error... the critical thing is, to know how big your error can be in max.

100% accurate measurement isn't possible at all.

the.hamburglar

ok