EFI Quick Probe: Is this tool legit?

Have you not been satisfied with a cylinder balance test, noid light or test light?

A cylinder balance test is a very precise way of measuring cylinder contribution.

Have you done a cylinder balance test? If it passes, you'll probably need to look elsewhere..............

Fix the idle problems first. If you haven't already seen and gone through the idle/surge sticky, here it is again: "Surging Idle Checklist” for help with all your idle/stall problems.

I have that tool, and it is a very quick way of knowing if the injector is opening. it will not tell you if the injector is plugged, it just flashes if the injector solenoid is working. It is a quick and fast way of doing a preliminary check. Faster than installing a noid light. If this tool does not flash while on the injector while the engine is running, then I put a noid light on, if the noid light flashes, then I know for sure and for certain that the injector is bad.

And a CBT will tell you that for free.

A Multimeter or DMM will test the wires and is a lot cheaper and has other useful functions. The wiring for the injectors is simple to test using the low Ohms (typically 200 Ohms range) to test the wiring for broken wires and bad connections.

Remove the passenger side kick panel and loosen the 10 MM Hex head bolt that secures the computer connector to the computer. Pull the connector out of the computer.

The red wire on each injector is the power source and the other wire is switched ground provided by the computer. The resistance of the ground signal wire coming from the computer will be between .5 and 1.5 ohms measured from the computer pin and the same wire color on the injector.

Injector switched ground #1 - tan wire, pin #58
Injector switched ground #2 - white wire, pin #59
Injector switched ground #3 - brown/yellow wire, pin #12
Injector switched ground #4 - brown/Lt blue wire pin # 13
Injector switched ground #5 - tan/LT blue wire pin #14
Injector switched ground #6 - Lt green wire pin #15
Injector switched ground #7 - tan/orange wire pin #42
Injector switched ground #8 - lt blue wire pin #52

Computer connector as viewed from the computer side


If you come up with a resistance reading higher that 1.5 Ohms, the 10 pin connector is suspect. The black 10 pin connector contains all the injector wiring connections to the main wiring harness. Separate the black connector and clean and tighten the pins. See http://www.oldfuelinjection.com/?p=85 for the how to do it article.

While the wiring is disconnected, measure between each of the ground signal wires coming from the computer and ground. You should see an infinite open circuit. A wire shorted to ground will read less than 100 ohms, and needs repair or replacement. See http://www.oldfuelinjection.com/?p=7 for help in that department.



Diagram courtesy of Tmoss & STang &2birds