I have a 96 5.7L Vortec Chevy Tahoe which I bought a month ago.
I was checking the sensor values using an OBD2 connector and noticed that the MAP sensor is not producing good values.
I see 28 kPA / 0.977 Volts when idle and 27.7 kPa / 0.918 Volts when throttle half open.
Now what I am wondering:
- What I understand is that the MAP sensor output should stay static when RPM is steady. Is this correct? What's the ideal behavior?
- Could this be because of a vacuum leak?
- Does anybody know if MAP sensor for this vehicle is 1 Bar, 2 Bar or 3 Bar type?
I can remove it and take a look but I have suspicions that the previous owners might put a wrong type of MAP sensor. Does this question even make sense?
UPDATE: After seeing comments about the need for more data and possible latency problems in the scan tool, I have managed to create a nice graph with more reasonable data.
Both charts are in the same time scale. I wanted to have 2 charts because otherwise lines go over each other too much.
With these charts, things look much better to me than I initially thought.
- A: When throttle is at ~25%, engine load is at ~55% and engine speed is at ~2000 RPM, I can see the MAP at ~70 kPa.
- B: 50% throttle, 100 kPa
But I don't understand C. When idling throttle position is %0, RPM is ~600 and the load is 25%. MAP sensor is at ~40 kPa which makes sense when I compare with engine load. This probably means the engine load is too high when idling, doesn't it?
Any suggestions to provide better data?