Hello all, i'm new to this part of the forum, although i have been a member for some time now. I have a AP power fc with boost kit and i am running a FD map sensor. The problem i am having is that my boost guage and my pressure sensor readings are not corosponding. i have the boost setting set to .6 kg/cm2 and my boost guage reflects this under WOT, but going back and looking at my commander, i show much less then that. Tonight it only read .27 kg/cm2.

So where do i begine to trouble shoot this?

I know the first question asked will be what my PIM value is set at. I have it set on value 1 "normal".

I have read some posts about calibrating the map sensor. My understanding is that a DL is required. Unfortunatley, i do not have one.

Any input would be greatly appreciated.

Steve

 

You will need a Datalogit and a MityVac or the like to calibrate your sensor. Remember, you can always buy a Datalogit, make PFC changes with it, and resell it.

Calibration is as follows:

https://www.rx7club.com/showpost.php...23&postcount=5

 

Just to clarify - while the PFC boost numbers are inaccurate with the pre-canned numbers, the difference is nothing close to the magnitude you indicate. I would suspect that your boost gauge is off too. Buy a MityVac to check both the PFC and your gauge.

 

This problem has been documented since 1999. Welcome newb.

If you search my posts, you will find the CORRET values to put in for the map sensor to make it correct. My tuning notes also contains these values along with the values for the Apexi 3 bar.

 

I would do some testing to see if the problem is in your boost gauge's reading or the PFC's reading. The PFC is typically a LITTLE bit off boost-wise, but if it's truly that big of a difference, something is VERY wrong, like "you could blow your motor" wrong.

Did you get your PFC used or new? I wonder if the "normal" boost sensor map was played with. If you haven't tuned it, it might be worth resetting the PFC back to factory defaults.

Dale

 

I did some further testing tonight. I hooked up my map sensor to my mity vac and put a "T" fitting going to a different boost guage. I pumped it up to exactly 8 psi on the guage that was hooked up to the mityvac. I then checked to see what pressure it was showing on my power fc. It was reading .37kg/cm2. Multiply that by 14.22 and you get 5.25psi. Is this to much of a difference to be a calibration problem?

On a side note, i think i may have uncovered a potential problem, although not the main problem. I have the vac line going to my map sensor teed off to my bov. I unhooked the vacuum line from the manifold and tried to pull vacuum on it with the bov and map sensor connected. To my surprise, it would not hold vaccum. I tested the bov to see if it would hold vacuum and it would not do so. I have never tried to pull a vacuum on a bov before, but i would imagine that it is supposed to hold vacuum . So this intern could be throwing off my map sensor reading sense they are coming from the same vacuum line. What do you think?

 

Never do such silly things!

Run two of the UIM side by side rear ports for the Map Sensor and your boost gauge. That way they sense the exact same pressure at the same point.
Run one of the front ports or side ports for the BOV.

 

Yes, i see know now that it is a good idea to have my map sensor and my bov coming from a different source. Is it normal for a bov to not hold any vacuum at all?

What about my first question, do i still have a calibration issue?

 

The stock PFC scale/offset used by Apexi in the PFC has been bad since day 1 of the PFC (since 1999). By 17psi, it is off by about 2 psi. But it requires a Datalogit to fix the problem.

Fix your problem first then give us the results.