Hi, I just installed a GM 3 bar map sensor, and have a question about the scale and offset in settings 3 in the FD3S datalogit. I asked/ looked around and found several different settings.

Rotary Performance - 43000/ 0 offset
Pineapple Racing - 46575/ 5592 (option 4)
Chuck Westbrook's notes - 43500/ 0
wRex-Racing.com - 41800/ 0

I drove the car today, using Rotary Performance's setting, and it seemed to run fine, other than hesitation at about 4500-5000 rpm, but when I'm driving normal in-town driving, it runs great.

Those of you run this map sensor, what do you have your scale/ offset set to? How would an incorrect scale/ offset affect how the engine runs?

Thank you very much.

 

With a MityVac or the like it is pretty easy to calibrate a sensor:

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

 

You need to study how a map sensor is used with a turbo charged EFI engine.
Map Sensor Voltage --> ECU : (1) modified by the scale & offset = PIM ABS pressure, (2) used to select P rows --> timing and fuel.

If they were off from what the tune in the PFC expects, then bad timing and bad fuel are the results. Unless you calibrate the old to new map sensors and adjust the MAP REF values, your engine will need retuning.

 

ok, thanks a lot. I'll calibrate the next chance I get. I need to get it tuned anyways. I'm still on the base map.

 

How do I read the PIM voltage? I have a datalogit, but not a commander. Thanks

 

Open up monitor on the Window menu, on you Datalogit.
It is the top value on the sensor row.

 

does the elevation the vehicle is being operated at affect the settings you should use?

 

It will change the offset - but should have no effect on the scale (which is a characteristic of the device).