my boost guage reads 13psi at max, but the datalogit gives me .75 - .76 which is about 10.8 or so -

what gives with the difference?

 

The PFC boost reading is known to be off. Go with what your boost guage is telling you.

 

 

the stock map sensor isnt very accurate and is known for being 1-2psi off.

 

I have never heard anyone on this forum say that the stock map sensor is that inaccurate. Please list your sources of info for that.

On the other hand, it IS well known and documented that the PFC commander displays lower boost than what the car is actually running (and what the PFC is actually seeing). If you run a ghost trace, you will see that even though the PFC may display 0.75, it is reading from the next highest load cell. It's an error in the PFC commander display, not an error with the PFC or the map sensor reading.

 

ok, sounds good - thanks!

 

oh really, i had always thought the difference between the pfc reading and a real boost gauge was due to sensor inaccuracies. thanks for setting me straight.

 

When I turn my ignition on, but do not crank the car the PFC reads -40. I thought there was a problem with my MAP sensor so I replaced it with the GM 3bar. It still reads off, Today I'm going to check the grounding around the PFC and see if that might help, I really would like for the PFC to show accurate information.

 

its reading absolute pressure (or pressure relative to sea level...cant remember which) when there is a negative number. Theres also a way to change it so it reads zero. Search for it in the PFC forum

 

I would say the guage is more accurate its using actual vac pressure for its reading. less computer calculations involved

 

yea, i've been meaning to ask since the reading on the commander is off how does that affect the performance. if the PFC is thinking it's seeing 10psi but in reality in'ts 12psi i would imagine that's big trouble, but i guess it's an error with the commander and not the actual PFC unit. good to know.