1999 LeSabre running temp/idle questions - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 12-06-2010, 08:53 AM   #1
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Default 1999 LeSabre running temp/idle questions

New thread!! Yes the 1999 Lesabre is running again after the UIM failure, but has some lingering issues.

1) The car has been "burped" several times and the coolant level is fine. After warm-up yesterday, with the heater in the "off" position, the engine temp climbed to 195 according to the guage. the system built pressure and the upper radiator hose was hot. At 195, both fans kicked on and instantly dropped the temp to 160, where the car seems to like to run all the time. the thermostat is new, but the old one behaved the same way. What is happening? the fans shouldn't kick on until over 200? could the gauge be wrong? Bad temp sensor?

2) I have a high idle problem. Even when hot the car idles at 1000rpm. I removed the IAC and cleaned the "port" it opens and closes, I have cleaned the throttle body, I have checked every vacuum line and connection 5 times, complete with spraying every line and connection with Carb cleaner with no response. Could the IAC not be closing all the way? could it be related to the temp issue? How can the IAC be tested?

I would appreciate any help or insight. My girl says the car runs the same as it did before the UIM failed and was repaired. IE--it always idles high, and the temp always sat at 160.

what is a man to do to fix the car that carries his family?

thanks---
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Old 12-06-2010, 09:00 AM   #2
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Sounds like a bad temp sensor. The temp should go up to about 215 or so, then drop to perhaps 180-190. You idle is controlled in part by the ECT. If the PCM thinks the engine is cooler then it is, say 150 instead of 200, the idle will be higher. Changing the ECT is not to much work, but will need to have some coolant drained.
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Old 12-06-2010, 04:15 PM   #3
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Do the radiaotor fans get their information to turn on from the Temp sensor? I can understand the temp sendor being out of whack, and giving a wrong reading at the dash, but if the temp sensor thinks the engine is cooler than it really is, wouldn't it be telling the rad fans the same thing? " I'm cool and don't need fans?" Maybe?

thanks Danthurs---you' ve been a real help--
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Old 12-06-2010, 04:28 PM   #4
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Ya, they should turn on about 210 and 220 depending on the fan.

Other things to check is the PCV valve, and the EGR.
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