MSefi.com read only forum (Jan.15,2018)

Hello,

I have been testing my MS-II V3 board for use with a fuel composition sensor. Initially I was consistently seeing ethanol percentage values of about -6% in TunerStudio. Bench testing of my sensor revealed that it was always sending a signal of about 43Hz.

I obtained another fuel composition sensor which bench tested OK. However now that I have hooked it up to MegaSquirt, I am not seeing any reading for the sensor in tuner studio. When I connect my multi-tester to JP4 on the MS daughter card I am seeing 111Hz and about 3.26v DC. TunerStudio always shows the ethanol percentage to be 0%. This is true whether the sensor is connected or not. And it is also now true for the non-working sensor as well.

I can read the sensor output on the JP4 pin with my meter, but the ethanol percentage shown in TunerStudio remains pegged at 0%.

I have wired the flex fuel sensor as recommended at http://www.megamanual.com/flexfuel.htm, with a 10K Ohm pull up resistor from the proto area 5v to the sensor output lead. Is there anything I can do to further verify whether MS is seeing the signal on JP4?

Maybe I should clarify the problem I am having with MegaSquirt and the Flex Fuel Sensor....

MegaSquirt was working fine and I was seeing data from the fuel composition sensor in TunerStudio. However, the fuel composition sensor was bad. It was sending a signal <45Hz indicating an error condition. Also I later discovered that the bad sensor occasionally emits a high voltage on its output wire. While bench testing, I have seen spikes of approximately 12v.

I have swapped out the bad fuel composition sensor for another one that works fine. Unfortunately MegaSquirt does not seem to be seeing the sensor's signal any longer. If I connect my multi-tester to MegaSquirt JP4, I can see a 112Hz signal from the sensor. Unfortunately, nothing is showing up in TunerStudio.

I have a hunch that the voltage spikes from the bad composition sensor may have fried MegaSquirt's JP4 input circuitry. I have read in some other forum threads that the fuel composition sensor wiring instructions published in the MegaManual are poor and lack circuit protection for JP4.

Has anyone ever seen a similar problem where the JP4 input on a MegaSquirt-II daughter card stops functioning? If not where should I begin to look for an answer to this problem?

Thank You,
Brett