MS-II Oxygen Sensor Voltage Only Ranges 0.175VDC - 0.409VDC

[63Vette]

I recently upgraded my MS-I (v2.2 w/ flyback board) to a MS-II (blue board) in order to run flex fuel. Using the downloader, I pushed the latest firmware (v2.36) into the MS-II daughter board. Communicating with the latest release version of MegaTune 2.25, I changed the code variant to MS-II and activated megasquirt-II.ini.2.3.

The MS-I had been working extremely well with E-85, so I loaded the MS-I MSQ file into the MS-II. The vehicle fired off fine and idled. As it warmed, I realized that the O2 trim was pegged at its maximum. I found that the O2 voltage was only showing 0.409VDC; a values which never varied. Checking the O2 sensor's actual output, I found it was outputting 0.95VDC (or there abouts); obviously rich.

On the stimulator, I found that the O2 voltage only ranged from 0.175VDC - 0.409VDC. As a note, the MegaTune gages are set to display 0 - 1.0 VDC.

I re-flashed the s19 file and re-loaded the msq file, with the same results.

Any thoughts on what might be amiss?

Thanks much in advance!
Evan

[Bernard Fife]

Evan,

This is a known bug in the 2.36 code and the way it works with MegaTune.

To fix it, Calibrate the AFR table to DIY-WB. Click OK, and let it burn the 1024 entries. Then cycle the power, and recalibrate the AFR table back to narrow band. Click OK, and let it burn. Then you should be up and running properly with the narrow band sensor.

Lance.

[63Vette]

Thanks Lance! Works on the stimulator now.

Evan