On that whole 2 steps forward 1 step back path getting the cylinder reading working made me realize the multiMAP itself was really working right. When I saw the output didn't match the lowest cylinder I quickly told myself and all of you that's normal....no its not.
Attachment:
multiMAP.JPG [ 169.27 KiB | Viewed 3638 times ]
The blue is MAP1 voltage, which I confirmed with a meter, its right. The purple is the multiMAP output, it doesn't track right and never goes below 1.3V, but by 1.4V its not longer tracking right at all, so while it could read to about 37kPa, 40 kPa it had really lost any hope of calibration.
hmmmmmm........Pulled the wire out of the ECU connector and check with a meter...same answer
hmmmm......where's the circuit drawing, this is normally where I get myself into trouble because, yeah, I suck at electronics, but not today. The analog inputs on the ECU all have a 100k 5V pullup so when they are not connected to anything they read 5V which while often very helpful its buggering my NBO2 sensor reading and I thought maybe this too......but no. What's buggering this is the isolation amp, its apparently not setup right and doesn't have the correct range.. But, this thing is a pretty dead simple analog circuit, I just moved the output wire to bypass the amp and its pretty much fixed. Now I'm pretty sure the 5V pullup is causing voltage reading not to drop quite as low as it should, but that I can and did calibrate and now the MAP is about 1.5kPa above the cylinder reading at atmosphere, and about 1kPa high at the most vacuum I could pull....plenty close enough (red and orange lines)