Either one. When the sensors fail, it takes a couple of seconds before the computer decides to turn off the ASD relay. The fuel pump remains powered up and running for those few seconds but since the pulses coming from the failing sensor could be cutting out intermittently at first, there would be a misfire from the computer not knowing when to fire a coil or an injector. It all depends on how the sensor fails. To get technical, the signal voltage from the sensor varies from approximately 0.0 to 5.0 volts. There is a magic number where the interpretation in the computer switches from "on" to "off", and there is a gray area. For an example, lets say anything below 2.0 volts is "off" and anything above 3.0 volts is "on". Transistors inside any electronic equipment including some types of sensors really hate heat. When they get enough to fail, they rarely quit suddenly like flipping a switch. Instead, they might generate a 4.0 volt signal instead of the normal 5.0 volts. As they heat up some more that voltage might drop to 2.9 volts. That's in the gray area where the computer doesn't recognize it or becomes confused by something that is neither on nor off. It will ignore that pulse but the pulses right after that might reach 3.1 volts. That is high enough to be recognized. As that sensor continues to fail the misfires will become more frequent until the computer decides to turn off the ASD relay. All of that can happen within a few seconds or that could go on for many minutes. The misfires that can occur will feel exactly the same as running out of gas. One potential clue, but only if you can hear it, is the fuel pump will still be running for one or two seconds after the engine stalls. If you don't hear the pump, don't draw conclusions from that observation. Be aware that the air gap of your new crankshaft position sensor is critical. Depending on where it comes from there will be either a thin plastic rib molded onto the end of it or there will be a thick paper spacer stuck to it. Push it in all the way until those make contact with the ring on the flex plate. If you remove and reinstall one with the plastic rib you are to cut the remaining part off and use a paper spacer from the dealer. If you don't use some type of spacer, the sensor could contact the flex plate and be broken.
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Saturday, March 26th, 2011 AT 8:45 PM