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.

[GregAmy]

Trace the power side of the connector to see if it's going to pin #4 (specifically "IV") on the white 4-pin connector on the relay plate. The wires are all white so you'll have to disconnect both sides and use an ohmeter. For reference, the pins are as follows:

I - powered from the power relay, should be hot with the key on
II - powered from T14-1 start power, signal to computer of the starter being engaged
III - ground side for fuel pump relay, controlled by computer
IV - Power from T14-1 starter circuit to power the CSV

Then go to the ground side of the CSV connector and disconnect the thermoswitch; I'd not be surprised if it was still grounded, indicating a wiring short between the CSV and the thermoswitch. If not, then you can ohmeter the switch at room temperature to see if the circuit is closed (it should be open); then let it cold-soak in your home freezer and see if the circuit is open (should be closed).

Finally, if you're at ambient or above and the CSV is working and you disconnect the CSV plug and the car runs poorly...that tells me the engine is running lean and the CSV is making up the slack. So you might actually have three issues...get the car running without the CSV connected, because that's the way it's supposed to be above freezing temps.

Apologies for the red herring.