2005 Lesabre doesn't idle until engine warms up.

Deamer1

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I have a 2005 Buick LeSabre with a idle problem. When the engine is cold (like sits in the garage overnight) It will start every time, no problem starting, but it will not idle until the coolant temperature reaches almost normal operating temperature. It starts, but if I don't use slightly more gas pedal than idle it will die. And it will continually die each time the accelerator goes to idle position, like taking your foot off the gas pedal approaching a stop sign......it will die every time.. Until the coolant temperature Gets close to operating temps. Then and after that it is fine, until the engine cools down and then the problem is the same. Yesterday I started the engine with a cold engine and waited until the coolant temp got to 194 degrees and started driving, went approx. 20 mile....stopped for two hours, coolant temps were then approx. 130 - 150 degrees. It Drove just fine.
Today it was cold, coolant temps approx. 50 some degrees. It wouldn't idle until the coolant temps reached in the high 180's .
Anyone have suggestions what it could be?
There are no trouble codes.
The coolant is full and clean (New) Also new thermostat and gasket.
Air filter is new.
Oil is fairly new and up to proper level
Battery is good, specific gravity tests good level, voltage is proper, electrolyte is proper level.
I thought maybe it might be the TPS, but don't know where it is on this Buick. Also I don't know exactly how it operates under different conditions.
Any and all ideas are very much appreciated.

deamer1
 

MelsRegal

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some engines have two coolant sensors, one for gauge the other for the PCM, your PCM sensor may be the issue. The other thing is check for a vacuum leak. Hoses are 13 to 14 years old.
 
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Deamer1

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some engines have two coolant sensors, one for gauge the other for the PCM, your PCM sensor may be the issue. The other thing is check for a vacuum leak. Hoses are 13 to 14 years old.
Thank You for the good input. I had no clue there were two coolant sensors. I will check them out ASAP! Will post results when completed.
 

HotZ28

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Thank You for the good input. I had no clue there were two coolant sensors. I will check them out ASAP! Will post results when completed.
There is only ONE coolant sensor on an '05 LeSabre. The older models 95-and below had one sensor for the gauge (one wire) and another for the PCM (2-wire) located under the T/B.
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Deamer1

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There is only ONE coolant sensor on an '05 LeSabre. The older models 95-and below had one sensor for the gauge (one wire) and another for the PCM (2-wire) located under the T/B.
I found the coolant sensor. It's located on the bottom of the thermostat housing. Haven't had the time to do any testing. Will post again. Thanks for the input.
 

Deamer1

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Getting back to my idle problem....
I did find the coolant sensor located under the thermostat housing. Didn't do much with it at that time as I didn't have my DVM for testing.
However, I did take a spay can of WD40 and sprayed all cables and linkages that appeared to hook into the top of the engine on the back side. (Probably sprayed cables that didn't have a thing to do with my problem, but applied the theory that if a little bit helped some, then a lot more would be even better!)
This morning I Started the car with the coolant at approximately 60 degrees F. Let off the accelerator and IT DID NOT DIE! I drove it approximately 35 miles without a incident of stalling/dying! Drove it again approximately 40 mile and it again operated as it should without a incident of stalling/dying. (Lots of stop/go driving) Who woulda Thunk?
So, I didn't pursue the coolant sensor since that seemed to cure the problem.

Thanks to those who responded to my problem. It did help me and I learned a few things.
Enjoy your week!
Deamer1
 

HotZ28

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Thanks for the reply! WD40 (Water Displacement 40-th formula) can work wonders on +- terimanal contacts that are damp or corroded. Anytime I disconnect a wiring connector under the hood, I apply a slight coating of dielectric grease in the connector before reassembly. https://en.wikipedia.org/wiki/WD-40
 
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