The injectors are supplied with voltage when the key is on continuously.
When the vehicle is cranked, the pluse comes when the ECM grounds out the injector causing a circuit and a pluse.
THe information to the ECM comes from the Crank and Cam position sensors for the initial pluse. The width of the pluse, or open time of the injectors are influenced by the O2 sensors, MAF sensor, IAT sensor, ECT sensors, and TPS sensor.
How did you test for injector pulse?
Wednesday, April 2nd, 2008 AT 8:27 PM