injector resistance

[fatboybell]

I am still trying to chase down my rough idle problems.Today I eliminated the ignition system,maf connector,and vacum leaks.I read the article on checking injector resistance.I am confused because it says to hook a meter to the battery,then to your injector wire and then measure resistance.I have never checked resistance using battery voltage.Is this a new style of meter,because normally you do not hook an ohmeter to a power source.What am I missing?

[Jesda]

The injectors are tied to the rest of the vehicle's electrical system. You complete the circuit and check the resistance.

[elwesso]

The injectors fire by the ECU grounding them (I think)... Thats why theres only 8 wires going to the ECU for the injectors, instead of 16...

Im really not sure why you do it that way... maybe Robert can chime in.. But thats how its done so i can live with it!

[DAEDALUS]

The intent is to measure through the positive cable back through the injectors. You''re not measuring through the battery since that would probably burn out the meter (but you can confirm this by taking a voltage measurement). I'm only concerned that by measuring through to the battery cable, the measurement may not be accurate--I don't think the injector circuit is isolated. The method I've always posted mirrors the FSM. There is a 2nd connector near the 8-pin connector that provides 2 more terminals for measurement. If you go through both connectors the injector circuits are completely isolated.

[autotech43]

The injectors work with a power supply and a pulsating ground from the ECM (engine control module). Keep in mind that the diagnose can be tricky, due to the resistance value be within specifications and you CAN still have a faulty injector. The injector and circuit may check fine electrically and the injector not be working mechanically. I've seen through the years that folks can get burned by thinking the electrical test is the only check for a accurate diagnose.

[Q45tech]

Power balance test to see if loaded [AC on] and unloaded [Ac off] variations are within a 13 rpm range [ie 87-100, 75-87, 100-112, or similar].