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4 added charts for MAP and other stuff
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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 and more reasonable data.

enter image description hereenter image description here

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.

For example, A: When throttle is at ~40%, engine load is at ~55% and engine speed is at ~2000 RPM, I can see the MAP at ~70 kPa. B: Full throttle, 100 kPa

  • 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?

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 and more reasonable data.

enter image description here

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.

For example, A: When throttle is at ~40%, engine load is at ~55% and engine speed is at ~2000 RPM, I can see the MAP at ~70 kPa. B: Full 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?  

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.

enter image description here

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.

For example,

  • 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?

3 added charts for MAP and other stuff
source | link

I have a 96 5.7L Vortec Chevy Tahoe which I bought a month ago.

I was checking 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 sensor values using an OBD2 connectorneed for more data and noticed thatpossible latency problems in the MAP sensor is not producing good valuesscan tool, I have managed to create a nice graph with more and more reasonable data.

I see 28 kPA / 0.977 Volts when idle and 27enter image description here

Both charts are in the same time scale.7 kPa / 0 I wanted to have 2 charts because otherwise lines go over each other too much.918 Volts when throttle half open

With these charts, things look much better to me than I initially thought. 

Now whatFor example, A: When throttle is at ~40%, engine load is at ~55% and engine speed is at ~2000 RPM, I am wonderingcan see the MAP at ~70 kPa. B: Full throttle, 100 kPa

  • 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?

But I can remove itdon't understand C. When idling throttle position is %0, RPM is ~600 and take a look but I have suspicions that the previous owners might put a wrong type ofload is 25%. MAP sensor. Does this question even make 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? 

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?

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 and more reasonable data.

enter image description here

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. 

For example, A: When throttle is at ~40%, engine load is at ~55% and engine speed is at ~2000 RPM, I can see the MAP at ~70 kPa. B: Full 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? 

2 added 4 characters in body
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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?

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?

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?

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?

1
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