What is this ground wire?

[berndtj]

While removing the broke cruise control, I noticed this ground wire(s) just dangling. I’m wondering what it goes to. The other disconnected wires are for the cruise control, and I believe the O2 sensor (which has been deleted by PO).



I’m assuming it’s part of the lambda system, which won’t work without the O2 sensor.

Thanks!


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[berndtj]

Maybe I should include it’s an 83. Thanks.


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[gazzerr]

That's usually connected to the outer stud on the number 3 cylinder intake runner. I can't recall what the wires are for without searching a wiring diagram. I'd assume CIS.

[berndtj]

Well that answers at least part of my question . Curious what parts of my CIS aren't actually working. I know the frequency valve is not doing anything, but I assumed that was because the O2 sensor was disconnected. It could also be that the ground is disconnected.

[Walt Fricke]

The FV should work with the O2 sensor disconnected. It's pulse width is then just set by the three position switch on the right side of the throttle assembly - one PWM value for idle, one for part throttle, and back to the same (rich) one for WOT.

You should always be able to feel a vibration in the FV by putting fingers on it with the engine running. Most of the grounds where gaxxerr puts it are for one or another CIS control feature.

These engines run fine (on the track, anyway) without use of the O2 sensor's input. Without the FV working, not so well. Hard to start. Did the previous owner delete the whole system? Is the silver box with the mini-ecu under the passenger seat in place? Can you confirm that the nearby relay which powers it is sending electricity to the ECU?

[gazzerr]

There's a bunch of stuff in that area so it's a ground for something like the blower fan (does it run?), cold start injector, throttle micro switches, FV, safety contact on the CIS air flapper, temperature switch, oil pressure light switch (I'd say those two are probably grounded internally to the engine case). If you trace the wire back you should be able to find out what those wires belong to. If you clean the dirt off the wires should be brown.

[berndtj]

LOL, sounds like a LOT is disconnected. It'll be a week or so till I get the car back together and see what happens when the ground is connected. I'm hopeful that it helps, as the car does not currently run very well, especially when cold. Nor does it feel like it's making full power (though I don't have anything to compare it to). The blower fan and WUR do seem to work, but the FV certainly does not.

In any case, thank you for the info. It's super helpful.

[gazzerr]

No worries good luck with it! Note I didn't mean that everything I mentioned was disconnected I was just spit-balling a list. If the FV is not running it will definitely run like garbage like Walt mentioned.

[berndtj]

I finally got my wheels back and was able to test drive the car since reconnecting the ground. Wow… what a difference. The cold-running problems are gone, and it’s much peppier. Basically fixed all the drivability and performance issues I had.

I have no idea how long the previous owner was driving it around disconnected. No wonder he sold the car.


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