Q: Runs fine with the map sensor vacuum line plugged off

asked by on October 09, 2016

If I leave the map sensor connected the enine load up and stalls. I already replaced the tps,map sensor,injectors, distributer , fuel pump and filter, ecm.

My car has 180000 miles.
My car has an automatic transmission.

Hello, the map sensor is an input of engine load. When the map sensor is disconnected it will set a fault code which is emission base and check engine will come on,this cause the system to go into a default mode. It uses engine vacuum as a measurement of that load. There is also an electronic aspect - the map sensor uses a five volt reference (0-5 volts). Zero volts would represent low engine load and 5 volts would be high load. You need the correct vacuum at the sensor to operate. Things that could affect this are having a vacuum line that’s plugged to the sensor or blocked at the intake manifold. There would be several steps to take in a diagnosis process. The overall health of the engine can create false input information to the computer (ECM). If you’d like, a certified technician from YourMechanic can come to your location to diagnose the issue.

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