MAP Sensor

[jmars55]

I was wondering if any one could let me know how to test my MAP sensor on the car. I have a 97 3.4 DOHC. I checked the referance voltage and it is a dead 5V. At idle I get a signal voltage of around 1.3V - 1.6V. As I give it a little gas the voltage dips to 0.6V -0.8V as I give it more gas it will climb to 2.5V then the it won't rev any more like it hits a rev limiter. Do you think the MAP sensor is shot or is there somthing else I shold do?

[HayesPerformance]

Testing a MAP sensor

Hey Jmars55,

There are a few things you will need to check your MAP sensor if you don't have a scanner:
1. Multimeter
2. Vacuum pump

First off I will tell you which of the three wires does what. On the MAP sensor starting at the conector closest to the vacuum port, the connectors are labeled on the sensor "A", "B", and "C"
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"A" (Black Wire) - SENSOR GROUND

It should read 0.7 OHMs or less between the connector and the body ground or the battery ground, if not "T" into that wire and run a ground to the body ground or ground at the battery. Test it again. It should read 0.7 to 0.6 OHMs.
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"B" (Light green) - MAP sensor signal to ECM

With the sensor CONNECTED, Check the MAP sensor voltage reading WITHOUT the engine running.
This represents a barometer reading to the ECM.
MARK DOWN THIS READING.
Apply 34kPa or 10 inch Hg of Vacuum with your vacuum gauge to the MAP sensor. It should cause the voltage to be 1.2 Volts LESS than the voltage you wrote down at the start.
Upon applying the Vacuum to the sensor the voltage change should be INSTANTANEOUS.
A SLOW VOLTAGE CHANGE INDICATES A FAULTY SENSOR!
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"C" (Grey) - Map Sensor and A/C Pressure Sensor Voltage Referance

This Wire Should have a steady signal of around 5 volts. If not check the wire coming from the ECM for breaks, kinks, etc.
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If you have any more questions just ask.

Best Regards,
David Hayes@
HAYES PERFORMANCE PLUS

[jmars55]

Thanks, I checked it and it looks good.