ECT reading ~50-60 degrees low

[Talyn]

Here's the deal, some time back after doing some work to my car it wouldn't start, I did some visual checking and found the wires to the ECT snapped right at the terminal end(ie. nothing left to splice back together). Naturally I went out and bought a connector, but it was an oval style connector and did not fit correctly. But everywhere I looked showed the oval connector for my car, thinking that maybe the owner swapped sensors or harnesses at some point, I decided to just get a new sensor to match the new connector pigtail. Well when it was about 40* out it was reading -14, and fully warmed up reads about 150, which I know can't be right, because my gauge which has never given me reason to doubt it(comes to temp normally, and has gone hot when I have legitimately overheated).

And because of this my fans won't kick on, and it actually made me overheat in traffic earlier today, I am also running so rich, that if I accidentally stall it out my plugs foul out instantly, I suspect because of the ECT.

While searching tonight, I did come across this thread:
http://www.dsmtuners.com/forums/newbie-forum/328009-resolved-2g-coolant-temp-sensor-question.html

Which seems to suggest that my 96 talon got an eclipse ECT sensor and harness. That being said, the very last post in this thread seems to suggest that the two different sensors are not cross compatible. Anyone else run into this problem?

Managed to connect the old sensor to check what it was reading, and it was correct, so if anyone else comes across this thread, do NOT switch ECT styles, it WILL read differently, in my case, I have a 96 talon TSI AWD, but the correct connector and sensor for my car are those listed for a 98 eclipse, at least on napa's site, not sure if the one listed for a 98 talon is the same or not.

 

[Disturbance]

This write up might have just saved me from junking my talon. Since i have bought it i have had the worst time ever figuring out what is going on with the ECT sensor. I have replaced it 4 times, it runs good for 50 miles than barely starts, runs super rich, than doesn't start and eventually the CEL comes back on for ECT sensor. No mechanic can figure it out or anything. My harness has been cut and a new one was put on that is square shape, so for clarification i should have a harness plug that is oval shape since i own a talon correct?

 

[Talyn]

You should have whatever your specific car originally did have. In my case, I originally had a square connector, swapped to an oval style because I couldn't find a replacement pigtail for the square, but switching to an oval, made my temp read low, best way to find out is to figure out what temp your ECM thinks it is, if the car hasn't been running in a while it should be pretty close to ambient air temperature, if the car is at operating temperature it should be around 200*.

 

[Disturbance]

Well I installed a brand new oval pigtail and sensor last week (I assume my car takes the oval one because when I look for that part for my car it shows the oval one) and still the same problem, barely starts and when it does it idles super rough, getting about 150 miles on a topped off tank of gas, and god forbid you stall the car because it will not start after that. I know it's the CTS because when I can't get it to start I unplug the harness at the CTS and than it fires right up. Can anyone please help me, I've been dealing with this for a good 4 months now and am about ready to just sell this thing.

 

[Talyn]

Like I said, it needs to have the same style as whatever it was manufactured with, if you removed oval connector, get oval connector and sensor. If it was square, then get square one. If you are really that lost it might be time to take it to a dealership imo. Especially if you don't have diagnostic knowledge and or tools.

 

[Disturbance]

well the pigtail that was in it was replaced by the previous owner because it was spliced in, this was oval shaped so maybe the previous owner had the wrong one in to begin with and i need the square one

 

[Talyn]

If you aren't sure then you need to view the ECT data from the ECM.

 

[Disturbance]

And what exactly do i look for? thank you for helping me so much, this is the only area on cars that i don't have much knowledge in. Also would link do all these readings for me?

 

[Arthris]

use a OBD scanner than has live data. Look at the Engine coolant temp and see what it says. As stated before if it hasnt ran for a while it should be close to ambient and if it was just running close to 200. If you get funky readings I would swap in the other style and if that still will not work pull the ECU and check the caps. Could be the caps have blown and you have acid eating the board away giving you this issue.

 

[Disturbance]

Ok thank you for the info, I think I'm gonna order link, I gotta pull my ecu out anyway for that so that would be a good time to check that