Injector Current Case Study

90 Pontiac T/A 5.7 PFI 117k Miles, this was a good test bed for the low amp probe since almost all of the injector's were bad. This thing ran lousy. Here are the waveforms.

#1 #2

Easy to find out of range injectors with the Amp probe, easy hookup if you can get to the wiring. Most of the Injectors here were out of the normal parameters, all were ohm'd out with engine at O/T. Cylinders #1, 12.7 Ohms and #2, 7.1 Ohms. GM says at 68 Degrees, 15.8-16.6 Ohms or about .5 Amp draw. With Engine at O/T resistance will be somewhat higher.

#3 #4

Cylinders #3, 8.0 Ohms and #4, 17.3 Ohms. Number four, the only good Injector.

#5 #6

Cylinders #5, 11.1 Ohms and #6, 14.4 Ohms.

#7 #8

Cylinders #7, 15.0 Ohms and #8, 10.7 Ohms. In closing, Ohm checking these cold may or may not give true readings, check them cold first, then check them hot.