Addicted2bass Posted June 23, 2011 Report Share Posted June 23, 2011 My TGP has developed a high idle problem. It will idle normally when its first started and the engine is cold. But once the car is driven the idle will increase to a point that the car is nearly undriveable. My tach is not very accurate but I believe its idling around 1k rpm in park when its first started. After driving for a minute or two the idle in gear will be around 1300-1600. In park closer to 2k or more. I replaced the IAC valve, but that actually made it worse. The idle was so high i could pretty much drive around town without my foot on the gas, the car would actually pick up speed and shift without my foot on the throttle at all. Did I get a bad IAC valve or maybe something else is causing the problem and the new IAC just exasperated it? I did the idle re-learn procedure before and after the new IAC, no change. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted June 23, 2011 Report Share Posted June 23, 2011 i wonder... have any kind of scanner nearby? this can happen if the ECM thinks the TPS is above 0% when it's actually closed. Quote Link to comment Share on other sites More sharing options...
Addicted2bass Posted June 23, 2011 Author Report Share Posted June 23, 2011 I have a mechanic friend who has a scanner that could pull that kind of info. For some reason I have no power at my OBD plug, although im sure I could jump power from the ign switch into it temporarily. Any idea why it would be worse with the new IAC? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted June 23, 2011 Report Share Posted June 23, 2011 you shouldn't have power at the plug... the only two pins that matter for an ALDL connection to the ECM is pin M(8192 baud link, 0-5V) and pin A(ground). no clue why a new IAC would make it worse... have your friend watch both TPS voltage and TPS% while both sitting still and moving around. if i had to guess, i'd day one of those is the problem. Quote Link to comment Share on other sites More sharing options...
Addicted2bass Posted June 23, 2011 Author Report Share Posted June 23, 2011 The scan tool would not connect to my cars computer. I've had this problem before, there must be a wiring issue somewhere becasue I have tried other scan tools in the past and they would not connect either. My friend did tell me that the problem may be caused by the coolant temp sensor. The idle is fairly normal when the engine is cold and gets bad once the engine warms up. He said he has seen the same problem on this engine before. Also my temp gauge on the dash has always read hot, if its a warm day and im at idle for a minute or so it will get right up to 220. I figure its worth a shot to change out. Quote Link to comment Share on other sites More sharing options...
Addicted2bass Posted June 30, 2011 Author Report Share Posted June 30, 2011 The coolant temp sensor fixed the problem. Car is idling normally again! Quote Link to comment Share on other sites More sharing options...
valeck25 Posted October 27, 2011 Report Share Posted October 27, 2011 I have the same exact problem and I would like to try your solution I would be very thankful with your help thanks Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted October 31, 2011 Report Share Posted October 31, 2011 I have the same exact problem and I would like to try your solution I would be very thankful with your help thanks The temperature sensor below the thermostat area(if you have a 3.1 like the original poster). The other temp sensor on the rear cylinder head(1 wire) only operates the temp gauge on the instrument panel. Quote Link to comment Share on other sites More sharing options...
wizkid1795 Posted July 7, 2012 Report Share Posted July 7, 2012 I've got a 2000 Grand Prix GTP that idles high and the air conditioner randomly switches back and forth between hot and cold so it feels like its having hot flashes. The temp sensor has been changed and it has been checked for air leaks but the issue remains any ideas on what the issue could be or how it might be repaired? Quote Link to comment Share on other sites More sharing options...
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