Boost gauge not reading correctly
 

I've got a P3Cars Vent gauge, and while I'm mostly using it to keep track of my oil temps, I've noticed the boost seems to be reading incorrectly. At idle I'm between -18 and -21, which seems about right, but at full boost it's only reading at 4psi when I'm actually boosting about 9. Since it's going through my OBDII I'm not sure why it would be reading so low. What am I missing (probably a lot)?

Are you using the stock sensors? It may be maxing out :)

Yes I am but I haven't heard about needing to change the sensors before. Other people with boosted 86s using the same gauge haven't mentioned it. Would I just change my MAF?

You need to change your MAP sensor (and get a reflash to accommodate that sensor).

Thanks. So does that mean the stock sensor just doesn't read past 4psi?

i thought it was 7psi

i got about 5.3psi out of my stock one.

i believe it's 5.3, but only if your tuner expands the scaling to go that high.

This. Also remember that if you do get a different MAP sensor, your tuner needs to adjust the scaling for it or your car might not run.

Good to know. Thank you guys for all the help again.

I also thought the stock would read up to seven. That is where all the tuners say you will need a map sensor to go higher. Well either way good to know.

This. I have a 3BAR sensor in my car, but my boost readings through ECUtek data log reads a max of about 4psi. My car still runs though.