Jan 222015
 

The car runs good until it warms up to running temperature then it wants to bog on acceleration and stall out, I try to scan it but I get a connection check notation and no communication with my scanner.

  One Response to “1994 corvette”

  1. usually a blown radio or cigar lighter fuse will cause a NO Communication error with the scan tool.

    The engine uses preset parameters until it reaches normal operating temperature. Would be much easier to find if you could pull the codes. Your local parts dealer generally will do this for free.

    You can rule out fuel pump, fuel pressure and any spark related parts. It is possible that you have a vacuum leak somewhere causing the sensors to send an inout signal to the PCM to cut back on fuel or increase it depending on the leak location if there is one. I would lean more toward a failing sensor if no vacuum leaks are found. Check the Engine Sensors. Check MAF first.

    MAF – Mass Air Flow Sensor Testing

    1.Visually check the connector, making sure it is connected properly and all of the terminals are straight, tight and free of corrosion.
    2.With the engine running, lightly tap on the MAF sensor and wiggle the wires at the connector and watch for the idle to change. A common problem is MAF sensor wire damage.
    3.Backprobe using a DVOM set to the Hertz scale between terminals A and B. Simulate operating conditions by blowing air across the sensor. There should be a frequency swing from the air crossing the wire in the sensor. A normal flow signal will be close to 1200 hertz. If the frequency is not shown, or not proportionate to the air blown across the sensor, the sensor is faulty.

    how to test a MAF sensor

    4.Check for battery positive (B+) on terminal C and ground on terminal B. If voltage or ground are not present. check the circuits back to the PCM for continuity.
    5.If you receive the proper amount of voltage at the electrical connector and still have a driveability problem, replace the MAF sensor.
    6.If the sensor and circuits are functional, the PCM may be faulty.

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