CIS Temp Switch

[Superman]

Here's a pretty esoteric question, but I have faith someone will understand it. On my crankcase breatehr plate at the rear center of the engine there is a threaded hole and a 35-degree temperature switch. I believe this switch tells the CIS system when the engine has reached 35 degrees C, at which time the CIS computer adjusts the mixture (leans it I bet).

My switch is no good and will be replaced. It very probably has been bad for a long time. When I fire up this newly-rebuilt engine with a new temperature switch, is it possible that when the switch turns on, the CIS system will become too lean?

BTW the car started and operated like a dream at any temparature, with the bad temperature switch.

[wckrause]

Is that switch seperate from the thermo-time switch that controls the cold start injector? I'm not so familiar with those Computer controlled CIS systems.

[Jdub]

I was going to reply along Bill's lines...that this switch prevented gas priming due to temp of engine.

But can I expand a bit? What do you define as "started and operated like a dream at any temparature..."? Did you ever have a momentary stumble, where the idle went quite low then recovered? I have been experiencing this recently and cannot figure out if I need to readjust the CO or what. Temp has been around 30 to 40 degrees.

Anyone with the low-near-dying-then-recover at cold startup? Any fixes for this?

Thanks mightily,
John

[wckrause]

John,

Sounds like your WUR might need a little adjustment. The little stumble means it's a little lean at start up.

Don't adjust mixture to fix a cold start problem. Set your mixture for best operation at warm temps, and then fix the cold start by adjusting the WUR.

[Jdub]

Thanks Bill - I will take your advice and start by setting the CO at fullup warm.

As to the WUR, that thing scares me a bit since I took it out and could hardly get the square-end machine screws back into the block! But I do remember it seemed clean and the little hole-and-pony show reacted nicely to current. But as for moving that pin, well, I might need some hand-holding here! I will pull out the tech article and have another look.

Thanks again,
John

[Superman]

Thanks for the input guys. I'll check my Bentley. Perhaps this switch is just part of the thermo-time cold start valve thing, in which case neither hot nor cold running mixture will be affected, except at startup.

I know my car does have a separate 90-degree sensor that does impact the mixture control.

No, my SC does not do the almost-die-then-recover bit, but other cars I've had did. I'd guess Bill is right. Partly because Bill has a habit of being correct, and partly from my own experiences.

[Early_S_Man]

Hey, Jim!

That switch goes right to the OXS system control unit, so forget about the cold-start enrichment circuit suggestion!