Hi all,

I was testing my injectors today for the first time with the PowerProbe 4 on injector mode and noticed that one injector did not appear to be firing correctly when measured at the injector terminal via back-probing. However, when back-probing at the wiring harness beside the fuel rail the corresponding injector signal was displaying consistent normal values. Therefore what should I conclude from this? The probe was piercing the insulation and making good contact in all cases. Listed figures are maximum or minimum values recorded over a period of 15 seconds.

Table 1 - measured injector values at the wiring harness:

Injector # On Time (ms) Inductive Kick (V) Ground (V) Positive (V)
1 2.7 - 3.1 70.5 0.42 13.7
2 2.7 - 3.1 (no glitch observed) 70.5 0.42 13.7
3 2.7 - 3.1 70.3 0.42 13.7
4 2.7 - 3.1 70.2 0.42 13.7













Table 2 - Measured injector values at the injector terminal:

Injector # On Time (ms) Inductive Kick (V) Ground (V) Positive (V)
1 2.8 - 3.4 70.5 0.42 13.7
2 2.8 - 155 (intermittent glitch) 70.5 0.42 13.7
3* N/A N/A N/A N/A
4 2.8 - 3.4 70.5 0.42 13.7












*Injector 3 was inaccessible to back-probe directly at the terminal