I have the 0-5volt output of my wideband wired to the red/black wire of the A/C pressure switch, and have what seem to be the proper numbers entered in the custom data field on Datamaster (.0390625 gain and 10 for offset, wideband paperwork states 0v=10:1, 5v=20:1, ratio=2xVoltage+10). The number in the Custom Engine Data Display seems about right (at idle, I have yet to drive it with this hooked up), but I can't seem to get it to display on the graph correctly. I selected A/C pressure, and it graphs it down there, but it still shows around 208psi when the wideband is at 14.7, and 452psi when the wideband is on LEAN (over 20:1 after it warms up---key on engine off). Engine running is the same, 14.7=208.x. I spliced into the red/black wire near the PCM, and wired in a switch to switch between A/C and logging. I know I wired it properly, because when I flip the switch, the A/C pressure shows, and changes appropriately when the A/C is switched on/off.

Any help would be greatly appreciated.

 

Maybe I'm just not seeing where to click to make the custom data number show up on the bottom right and the graph. Isn't that the whole point of this, to graph it with rpm, speed, etc., to see exactly where changes need to be made?

 

What kind of wideband do you have? In this writeup https://www.camaroz28.com/forums/com...riteup-535603/ he uses different values for the Innovate LC-1.

To see the custom data, you have to double click on one of the four boxes in the lower right of the datamaster screen( RPM, SPARK A, SPARK R, TPS%) and select what ever you want to graph. In your case select A/C Press.

 

It's a PLX M-300. I already did that, and can see it in the custom data window, but the ac pressure in the box to the right of the graph still shows like 208 for 14.7:1, and 452 for 20:1. I'm trying to get the AFR to display in that box.

 

hmm, just re-looked over your numbers and I come up with a gain of 0.039216
Not sure how much that would affect the output though!