dme

Looking at the DME temperature sensor, it looks like I should lower the level of the coolant before removing it. Being the lazy mechanic, will coolant come rushing out if I don't do this first? Draining antifreeze from this car can be a messy chore. I just got the garage floor cleaned up...

Droops83

If the engine is cold, only a minimal amount of coolant will come out if you remove the coolant temp sensor at most, if at all.

But, I will ask why you are removing the sensor?

dme

Thanks, I'm measuring infinite resistance between the terminals. Either they are very corroded and need a good cleaning or the sensor is kaput.
I'm starting to think nobody ever removes this thing.

Droops83

That could be an issue---when the engine is cold there should be very high resistance (I think a few thousand ohms, don't have the specs in front of me), but only a few hundred ohms when the engine is hot. So if your DME temp sensor was open, the engine would run very rich at all times.

Make sure you are checking the correct sensor: the DME temp sensor (NTC II) has the blue connector, whereas the temp sensor for that gauge has the two separate spade connectors.

dme

OK, this is something I definitely need to clear up. I thought the gauge sensor was the one with the single barrel type connector next to the throttle body and the DME temp sensor was down below the number one intake runner forward of the idle speed controller. I wish I could find a map for all appropriate sensors on the 951.

markl951

Both temperature sensors are next to each other and screwed into the cylinder head. It seems the one you might be talking about is the turbo coolant temperature switch. It's a switch and not a sensor. When the coolant temperature is not hot, that switch is an open circuit, i.e. infinite ohms on your ohmmeter.

Seattle 993

DME, the temp sensor is next to cylinder 1 and feeds data to the DME (no pun intended!) so that it can regulate more fuel when your engine is cold. I don't think it sends a signal to the temperature gauge on your dash, but I could be wrong. Never had to think about the dash temp gauge.

The cylinder barrel shaped connector in front and below the throttle body connects to a temperature switch (as the member before me said) that activates the electric water pump for the turbo after shutdown so that the turbo doesn't cook the oil when the engine is off and the water pump isn't circulating coolant.

Indeed, the turbo engine has more stuff like vacuum hoses and sensors - it can be very complicated. After doing a bunch of work in the engine bay, my car wouldn't start - but I had fuel, air, spark. Turned out that I had set the connector to the DME temp sensor but didn't fully seat it - and the only way I found it was to literally check all connection s by feel rather than sight. Learned a lesson on that one!

dme

I'm gonna have to pull the intake off again and really check things over. Fortunately I can remove the intake in my sleep now. When I had the intake off before I remember seeing the one temp switch (not counting the turbo temp switch), the IAC, the knock sensor, the cycling valve (CV), and the thermal switch with the two vacuum hoses.



In this huge picture which I should have reduced somehow, the sensor I'm referring to is circled. Which sensor is this and where in relation to it is the other temp sensor (not the turbo temp switch)?

Scott H

That one's for the instrument cluster, the one for the DME is forward of that a few inches, just out of frame to the left. It should be blue.

dme

By Gosh, you're right. I missed that underneath the water pipe and shielded by a large vacuum hose. I'm going back to retake remedial 951 engine 101...
Thanks to all.