Cold start injector Q Options

[rjames]

Should the cold start injector have voltage going to after the engine is warmed up? I thought that it was only supposed to fire when temps were below ~32 degrees. I haven't pulled the injector out to see if it's actually spraying fuel, but I'm pretty sure it is given the change in how the engine runs at idle when I unplug it, even after the engine is warm.

[rjames]

Are you sure?

My understanding form a post from McMark a while back here is that the cold start injector power wire is connected to the starter wire. Which means that it should only fire when the engine is cranking, not when the engine is running. So disconnecting the injector while the car is running shouldn't have any effect, regardless of if the thermoswitch is operating properly.
However, If I disconnect the cold start injector when the engine is warmed up, the idle starts to wildly fluctuate.

[GregAmy]

Are you sure?

Yes, I'm sure I was wrong earlier.

I rechecked my wiring diagrams and that's correct: at least on the D-Jet, the 12V comes from the starter circuit; specifically the 4-pin D-Jet connector on the relay plate, wire #4.

However, the thermoswitch closes the circuit to ground below around 32F/0C, so if the temps are above that the valve doesn't fire.

So you've got two weird things going on: power when the starter is not engaged, and apparently a ground somewhere in the thermoswitch side.