1980 3.0 sensors

[K Sykes]

Have done a lot of clean up of CIS related parts and wiring off of my engine now that I am on EFI. Thinking about using one of the no longer used sensor holes/sensors to get oil temp to use for the EFI ECU. Going from left to right, I have the thermotime switch, oil temp and pressure that feed the gauges and a fourth sensor all the way to the right that I don't know what it's for other than it doesn't do anything in my current set up (nor does the thermotime). What I was thinking of doing was using the left most sensor (assuming it's reading temp) or using one of the two threaded holes to for the thermotime or the one on the right to use as a temp sensor. I am the Tbitz sensor on a chain cover bolt which works fine, but was looking for something that was measuring the oil itself.

So two questions;
1. Can someone tell me what that right most sensor is/does?
2. Is the threading on either of those holes the same as a standard temp sensor?

[James Brown]

here, add this to your library CIS Primer for the Porsche 911

[boyt911sc]

Kinsley,

Are you referring to the right side chain cover's temperature sensor (15°C/59°F)? Late SC's (80-'83) all have this temperature sensor mounted on the chain cover for 4-5-6 cylinders. Post a picture for better communication.

Tony

[K Sykes]

Tony

Yes, that one. I'll post a pic in a bit.

[psalt]

Kinsley,

That is not a sensor, it is a switch. It is the switch that triggers closed loop operation. The thread size is 14 mm x 1.5. In my experience, this is not a good location for a variable resistor EFI sensor. It is not in direct contact with pressurized oil, it just sees inconsistent splash. An EFI (water cooled) coolant temperature sensor does not work well in this location. You are better off with a cylinder head temp sensor for warm up enrichment. On all the conversions I've done, oil temperature takes much longer to warm up and give consistent readings than the required cold running enrichment curve.

[K Sykes]

Paul,

Thanks, that all makes sense, but not what I was hoping for. Just trying to take advantage of some unused real estate. The CHT idea makes sense too. I have good warm up from a dead cold start, but less so from a start where the engine has been sitting for an hour or so, but still warm.

Thanks for all the answers.

[psalt]

Kinsley,

If it is slow to fire on a warm restart, lower the hot cranking pulsewidth. If it fires and then stumbles when warm, look up where you are on the map and lean it out. Warm engines need very little idle enrichment. Dialing in warm restart with EFI can be tricky. I have carbed engines that fire so fast they seem to be waiting to go. Some EFI ECU's need a few cranks before they want to make any decisions.