Mighty Shilling

I dunno what they are...I've heard a couple of things though... here's what I'm experiencing:
-running rich (something my Porsche tech said could cause richness was the engine temp sensor)
-temp gauge needle...until the engine is warm, appears to read normally. after warmed up, rides right at the middle line, then instantly jumps to 3rd line, then down a little, then into overheating, then back down...Dad suggests this is the sensor....

any other potential issues that could be caused by a bad temp sensor?

thanks!
-Geoff

by the way, I'm not overheating when the gauge jumps up...because it's not a smooth run up to overheating, I'm pretty sure that it's either a ground or a sensor.

Mighty Shilling

Oh yeah...my fans work well...they come on...right on time...so I'm guessing the fan switch works...

ahofam123

There are 2 temp sensors. The one for the early temp guage will be a single wire that slides onto the end of the sensor. The one for the DME will have a fuel injector type connection. If the guage reads high or low, then check to see if the sensor for the guage has any corrosion on it. If you are running rich, then test the sensor for the DME.

austin944

I think a jumping gauge indicates a bad connection rather than a bad sensor.
Try removing the wire and cleaning the connection, it's pretty easy to do.

Mighty Shilling

cool...I'll look into both...

if the DME temp sensor is dirty or corroded, can I clean it or is it recommended that I get a new one?

ahofam123

The DME sensor actually acts more like a switch than a sensor. With a cold engine, it will tell the DME to send more fuel, with a warm engine, it will run normally. With it being a fuel-injector type connection, it might be hard to get a brush in there to clean it. You could probably use a cotton swab or some of the electrical contact cleaner spray though. To test the DME sensor, see if the continuity (or resistance) changes as the engine warms up. if you end up having to replace it, it is about a $20 part from Napa IIRC.

Uranium-235

Haynes' has the various resistance measurements for the sensor. I think at full temperature it should read around 30 ohms.

Running rich could also be an O2 sensor.

Porsche-O-Phile

Yep, what they said. I'm actually wondering about this one myself. I've recently had an idle problem develop on the Voodoo 951. It wouldn't idle properly (ends up the idle screw in the throttle body backed out) so I fixed it per the Clark's Garage write-up procedure and thought it was fine. It ain't. Now it idles fine when hot but still rough when cold, so I'm suspicious that the DME temp. sensor might be messed up, possibly the O2 sensor.

Where is the sensor anyway? I want to resistance check it. Look under the Clark's Garage manual under "sensors" and there's a pretty good description of all of them and what they do / how to check. It just doesn't say where the heck the temp. sensor is.

Mongo

the engine temperature sensor is located on the head just behind the air-flow meter. You will see a wire plugging into it. Follow it and there's your sensor. I think I need to change mine too since my gauge is jumping..it could solve my richness issue too.

Mighty Shilling

hehehe...if only we were TRUELY rich...

Anyway, I know it's not the O2 sensor, did that last year. just did a FPR, so the two remaining on the list of things to kill running rich are MAF (god I hope not...it's not cheap) and the temp sensor.

Mike1982

I bought a new temp sensor becuase I know the connect is really rusty and just OLD so I am just waiting for time to replace it. I have noticed that my milage has gone down and it doesn't matter how I drive, could this be it? Everything else is new, plugs, rotor, cap, O2, etc.

Charlotte944

ahofam123:

I really hate to pop your bubble, but neither of the temp sensors are switches, they are both NTC, or Negative Temperature Coefficient resistors.

89magic98

OK, what happens if:

1. The engine temperature (resistance measurement) tells the DME the engine is cold, when in fact it has warmed up?
2. The engine temperature (resistance measurement) tells the DME the engine is at operating temperature, when in fact it is cold?
3. Does the cold-start enrichment effect what the DME does (in fuel injector pulsewidth) when starting the car with a cold engine?

Cyrus951

My jumpy temp gauge reading issue was solved with a new temp sender to GAUGE.

Jeff,

The DME temp SENSOR (It is not a switch), is located behind the airbox, it has a blue top.
I can upload a pic if you want.
They're cheap, about $25 new from Paragon IIRC.

Peckster

Idling rough when cold is often a bad head gasket.