CAN BUS - Irregular Readings

I purchased the CAN-BUS shield by sparkfun. The shield seems to be operating reasonably well and the example sketches were helpful for getting started. I’m plugging into the CAN-BUS of my car and have been able to read a handful of parameters (RPM, WaterTemp), but with a few hiccups.

My issue is that the values being printed to serial are not consistent and there seems to be other parameters printed as well. For instance, when requested values for the water temperature:

Water Temp: 97 degC
Water Temp: -40 degC
Water Temp: -40 degC
Water Temp: 97 degC
Water Temp: 97 degC
Water Temp: 97 degC
Water Temp: 97 degC
Water Temp: 97 degC
Water Temp: 98 degC
Water Temp: 98 degC
Water Temp: 98 degC
Water Temp: 98 degC
Water Temp: 98 degC
Water Temp: 1 V
Water Temp: 98 degC
Water Temp: 98 degC

I occasionally get a high value as well ~160 degC. This is essentially the case for all parameters regardless of whether my car is at idle, under load, or if I have lifted the throttle. It’s not directly linked to these conditions, but at the same time I do feel that they may contribute to the frequency of these values interrupting my readings.

I’m looking into this, but I am having a lot of trouble determining the issue because it’s working as I would like most of the time.

There are many things I would greatly appreciate help with to figure out:

  1. Insight into why I am seeing this variation in values.
  2. How I may go about getting consistent values.
  3. Parameters such as throttle are returning either 0V or 1V. How might I gain greater resolution into this value.

Ultimately, I would like to log these values and possibly display it to a lcd. I am not requesting any help with regard to those aspects of my project. I only mention it to give you an idea of the importance for values that are consistent and accurate.

Thank you for your time and any input will be very helpful.

AlteredDemo_AllParam.ino (1.96 KB)