Wont idle

[mitsueclipse2g]

Heres my problem, when it colds outside and I go to start the car it has trouble starting. It will crank over then stall. I have to give it a little gas to get it to idle, till it is properly warmed up. Some times when I drive and stop, it will stall out. When it is properly warmed up it drives fine and idles fine.

 

[96TurboGS]

Sounds like your coolant temp sensor is starting to go; change it. If that doesn’t work look into your O2 sensor. Should be either one.

 

[mitsueclipse2g]

This morning I unplugged the cool temp sensor and it still started, but i had to give it some gas. It idled really low though and died. It idled much better with the sensor plugged back in. About the o2 sensor, wouldnt it throw a CEL. I do have a CEL, which I recently got scanned and it is for the downstream o2.

 

[96TurboGS]

I would change it just to be on the safe side. It’s messing with your warm up enrichment's. If it doesn’t work you can always take it back to what ever part store you got it from. Downstream 02 shouldn’t have any major effect on your driving/idle.

 

[rstare]

I would change it just to be on the safe side. It’s messing with your warm up enrichment's. If it doesn’t work you can always take it back to what ever part store you got it from. Downstream 02 shouldn’t have any major effect on your driving/idle.

Your 02 sensor doesn't play a role in warm up. The ecu uses a fuel map in it's memory for warm up (Open Loop). Then after the warm up cycle the it takes the 02 sensors input and adjust fuel (Closed Loop); but this is after inital warm up.
You said you ecu was throwing a code for rear 02 sensor? Get a new sensor; start with something you know is wrong.
Check the IACV as well.

 

[96TurboGS]

Nowhere in that post did I say anything about the 02 playing a roll in the warm up, I said it was his clt. A sensor won't always throw a code to show it's screwed.

 

[rstare]

Sorry; I misread.
That is why it is better to say what exactly your referring to instead of saying "it".

I would change it just to be on the safe side. It's messing with your warm up enrichment's.

The last thing he mentioned was his 02 and the only thing you mentioned in your post was an 02, so I assumed that was what you were referring to.
Sorry for the misunderstanding.

 

[VelocitàPaola]

Sounds like your coolant temp sensor is starting to go; change it. If that doesn't work look into your O2 sensor. Should be either one.

I agree with this diagnosis. CLT's are cheap enough, so buying one and installing it should be your first attempt to fix this problem. You might also scan your ECU for codes; sometimes a DTC might be stored without a CEL showing up.

 

[mitsueclipse2g]

Ok here the deal I took it to a mechanic and had him check it out. He says that its the idle air control valve, Im not to sure about that one though. I think im going to get the coolant temp sensor, put it on and if it doesn't fix it, ill get the IACV and install it and see if that works.

 

[VelocitàPaola]

If you have a multimeter, the IAC is easy enough to check yourself. The resistance between the two outer pins should be approximately 36-52 ohms, as should the resistance between the inner two pins.

 

[mitsueclipse2g]

Now if I unplug the coolant temp sensor and the car starts. Does this mean that the sensor is good. I dont really think its the IACV, because the car idles fine once its warm.

 

[rstare]

AutoZone.com | Shopping | Parts | Product Detail - Coolant Temperature Sensor
Go get one of these and see if it fixes your problem.
Team 2GNT Forum - Viewing topic #91888 - Rough Cold-Start Idle
Most of the time when there is trouble on a cold start it is related to the CLT. So start with the known fixes and move on from there.

 

[mitsueclipse2g]

Ok i bought a coolant temp sensor and installed it, the car still wouldnt start when it was cold. It stopped stalling out whenever I can to a stop though. I went along and baught the IACV and installed it. After I finished putting it in the car started up right away and is running fine.