Replaced coolant temp sensor

[turbo_lag92]

just replaced the coolant temp sensor and i still have the symptoms i had before. the car idles at 2k, idles surges till warmed up, and the temp gauges moves a little bit but drops back down. air in the coolant lines is my next process. i don't know if it fixed my early morning starting problems yet either. it takes a few tries in the morning to start. anyone have suggestions?

 

[gofer]

1. Your CTS has nothing to do with your coolant temp gauge, its a seperate sensor.
2. You can tell if there is air in your coolant lines by turning on your heater full blast, if it never gets hot you have air in the lines.
3. Do you still have the FIAV on the bottom of the TB?
4. Have you checked for boost leaks?

How did the wiring to the back of the CTS look? 1g CTS connectors are notorious for crappy connections, just a quick re-wire might fix the issue.

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[9!'clipseDOHC]

Like Corey said, there are 2 coolant temp sensors, they are side by side on the thermostat housing. The larger one with 2 wires is the actual Coolant Temp Sensor. The other, smaller sensor right next to it with a single wire is the sensor for the temperature gauge.

Also like Corey mentioned the 1g wiring is usually brittle and/broken. Cut the hard, brittle section out and solder in some new wire and use a standard female spade connector on the end. The spade connector attaches to the sensors perfectly.

As far as your car idle surging when cold, I would suspect the FIAV, dirty/leaking TB, dead ISC, BISS out of adjustment/leaking.

Here are some handy links:
http://www.vfaq.com/mods/BISS-1G.html
http://www.vfaq.com/mods/wayback/BradBauer/engine/tb.html
http://www.vfaq.com/mods/wayback/BradBauer/engine/surge.html
http://www.youtube.com/watch?v=l7R3gf7SiAo


Hope this helps!

 

[turbo_lag92]

connections were good no hard wires. i did the right sensor it was the two prong one.

 

[misterjose]

its in your throttle body, maybe your isc, your biss screw or the gasket is leaking. i had the same problems with my idle. i bought another tb from the classifieds and now it idles perfectly.

 

[turbo_lag92]

still didnt want to start this morning. wires are good and connected to the sensor. any other sensors i should look into?

 

[gofer]

still didnt want to start this morning. wires are good and connected to the sensor. any other sensors i should look into?

Did you do the checks the 9!'clipseDOHC posted?

 

[niddydsm]

wouldnt a leaky TB constantly idle surge and not just surge till warmed up?...I think it sounds more like a ISC with the high idle and roaming

 

[9!'clipseDOHC]

wouldnt a leaky TB constantly idle surge and not just surge till warmed up?...I think it sounds more like a ISC with the high idle and roaming

Depends on which part of the throttle body is leaking. The lower half contains the FIAV which has the sole purpose of raising the idle on cold starts. There is a waffle gasket which divides the lower half from the rest.

 

[e30_fiend]

Bad gasket cause problems when cold because the metal is cold and the tolerances between the two pieces of metal is larger than when its at operating temp. Once your car warms up, the metal expands enough to close the gap at least enough to mask the problem. So in short, change all gaskets, seals and o rings associated with the throttle body. Yeah its a lot to do at once but you won't have to do it again for like 50k miles.




Taylor

 

[turbo_lag92]

i did not think the throttle body would mess with it cold starting?

 

[gofer]

i did not think the throttle body would mess with it cold starting?

The FIAV (fast idle air valve) is attached to the bottom of your TB. Its there to provide additional air when the engine is cold to increase the idle speed, which in turn, warms up the engine faster. The coolant flows around a small wax pellet, which is in the FIAV. As the coolant temperature increases, the wax pellet melts and the FIAV closes, which slowly decreases the amount of extra air that goes into the engine.

 

[9!'clipseDOHC]

i did not think the throttle body would mess with it cold starting?

Well now you know.

 

[TenjinChan36]

How did the wiring to the back of the CTS look? 1g CTS connectors are notorious for crappy connections, just a quick re-wire might fix the issue.

I just had a problem with wiring this morning...at least that's what I think. I know I have a Check Engine Light for this sensor and upon checking the wires they had been spliced terribly. I still have cold start problems after leaving the car parked over 24 hours. The light has not cleared since I've fixed the wiring so I'm assuming it's the same code, have not checked yet. Fixing the wiring helped get her started in general...running pretty well until today. After cranking 20 minutes like a moron I jiggled the wires on the sensor and she fired right up.

 

[gofer]

To clear the code disconnect the the battery ground and SOLDER the wires to the new connectors, that way you don't have to 'jiggle' them everytime your car doesn't start.

 

[TJCTalon]

Very similare cold start issue im having as well.

I have a fresh 1g TB that was just rebuilt and the FIAV still there.

Im getting bad gas milage and takes a few trys to start when cold. Any tests to see if its my coolant temp sensor?