Map Sensor Testing

this is a vo by rich pin today we’re checking a GM map sensor now when a map sensor goes bad it can lead to excess fuel consumption and it can lead to engine surging also this one happens to be on a Saturn most of them are located in the intake manifold you can see it right here we’re going to start by removing the sensor from the manifold this one is held on by two seven millimeter head bolts now you remove the bolts the sensor will just come right out okay now we have the sensor out of the intake manifold and we want to find the green wire to the sensor and we want to back probe it that is the wire back to the computer I’m using a paper clip here at a bathrobe now this little gasket right here take this off the sensor because you’re going to be using a vacuum pump on that connection right there [Applause] all right now we’ll take a multimeter set it on DC voltage take the negative lead put that to a ground and then we’ll take the red positive lead and we’ll put that right there on our paper clip now we’ll take our vacuum pump I’ve got one of these small handheld pumps looks like that and we’ll hook the hose to this piece of the sensor right here now we’ll turn the ignition key to the run position we’re not going to start it we’re just going to turn to the run position and we should see something close to five volts and that’s correct now we’re going to take our pump and we’re going to pump the pressure and for every five pounds of pressure we should see something like a one voltage drop on our meter this five inches of vacuum and we’re getting for more sonometer that looks good now we’ll go to 10 inches we’re at 3 it looks good now go up to 15 that works good now we’ll go up the 20 1.14 volts roughly around 20 inches of vacuum now we’ll let that sit there a while see if we get any bleed down from

the map needs to be holding steady now if once you hook that up initially if you got no voltage on the reading well then you need to check the live wire to the map sensor or the ground wire that the other two wires live and ground if you don’t have any initial voltage when you hook it up but this one seems to be working properly I’m getting a little bleed down on my vac gauge here but the map sensor looks good and that’s all there is to checking your map sensor