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13** No difference recognized between the engine MAP reading and the barometric (atmospheric) pressure reading from start-up

Whats that Mean in Idiot Terms I don't understand..
No light was on to check anything, I was just fooling around, and thought I would give it a try and see if anything was really wrong with it, first time I got 13 then the 55 (End of Test)
I waited about 10 mins to do it again and this time I only got 55 (END OF TEST)
So aanyone know?
 

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Well, here's alittle info on the MAP Sensor, then I'll tell you what happen:

OPERATION

The PCM supplies 5 volts to the Manifold Absolute Pressure (MAP) sensor. The MAP sensor converts what it reads as the amount of intake manifold pressure into a return signal. The PCM monitors the MAP sensor output voltage. As vacuum increases in the intake manifold, the MAP sensor voltage decreases proportionately. Also, as vacuum decreases, the MAP sensor voltage increases proportionately.

During engine cranking, before the engine starts running, the PCM determines atmospheric air pressure from the MAP sensor voltage. While the engine operates, the PCM determines the intake manifold pressure from the MAP sensor voltage.

Based on MAP sensor voltage and inputs from other sensors, the PCM adjusts spark advance and the air/fuel mixture.

See, what happen is when you where cranking the engine the MAP sensor took a reading, and then when the engine was running it took another reading and the voltage was the same,(it should be diffrent) so the PCM throw the code. You may have a bad MAP Sensor, or one that's starting to go out.
 
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