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Discussion Starter #1
my 92 sts has been running super poorly of late. the idle is abt 1800+ and at times it will sound like it is stalling out. i have changed the ISC and the TPS but there has been no change. i have done some research adn see people speaking of the IAC, Idle Air Control Motor, but i am not sure where it is, what it looks like or if there is a way to test it to see if it is doing what it is supposed to. also are there any steps that need to be taken for the computer after changing the parts that i have? i have done a basic mechanical inspection and replaced any bad vacuum hoses that i could find. would the egr cause problems at idle? i found the egr selenoid but it did not feel like there was any vacuum going from the sel to the egr valve. should there be? the other thing that i find odd is that when the car is idling high if i move the shifter from park to neutral or from neutral to park the motor will kick down and run abt 1100 rpm. still high but at least safer. i would really appreciate any help. i have also heard of a "min air" procedure that may need to be done but i do not know what it is or what steps need to be taken. thanks in advance.
eric
 

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ekvisto,
You need to properly adjust the new TPS. If you can't find the procedure on the internet: For most engines, set it at .5 volt with a mutimeter connected to the "test connection" provided near the TPS connector and the engine at idle. The engine has to first be at the proper operating condition idle (i.e. warmed up). The EGR valve should be closed at idle and have no vacuum applied to it. You can apply a vaccum to it (connect a hose with vacuum to it) at idle and see if the valve moves and the idle goes higher. If not, the valve is probably good. However, it appears you might have an intake manifold leak. You can easilly check the (Idle Speed Control) motor by carefully watching it to see if it is working. To check it, open the throttle until it clears the ISC motor "actuator" or "plunger" (which is connected to the "throttle switch" internally). Upon closing the throttle, the plunger should search for the correct idle speed by moving in and/or out. If it doesn't, you will further have to check the "throttle switch" to determine if it is working to tell the computer the throttle is closed. You could also remove the ISC and see if the engine goes to a very low speed below idle. If it does not, you probably have some kind on intake leak.

Pat

ekvisto said:
my 92 sts has been running super poorly of late. the idle is abt 1800+ and at times it will sound like it is stalling out. i have changed the ISC and the TPS but there has been no change. i have done some research adn see people speaking of the IAC, Idle Air Control Motor, but i am not sure where it is, what it looks like or if there is a way to test it to see if it is doing what it is supposed to. also are there any steps that need to be taken for the computer after changing the parts that i have? i have done a basic mechanical inspection and replaced any bad vacuum hoses that i could find. would the egr cause problems at idle? i found the egr selenoid but it did not feel like there was any vacuum going from the sel to the egr valve. should there be? the other thing that i find odd is that when the car is idling high if i move the shifter from park to neutral or from neutral to park the motor will kick down and run abt 1100 rpm. still high but at least safer. i would really appreciate any help. i have also heard of a "min air" procedure that may need to be done but i do not know what it is or what steps need to be taken. thanks in advance.
eric
 

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Discussion Starter #3
pat,

when you talk of adjusting the tps. is that hooking up a multimeter to the tps, with the wires unhooked to the ecm and adjusting it in the slots for the screws until there is a reading of .5? i noticed that the screw holes were elongated and figured that there must be some adjustment. i will remove the isc and see if the car returns to a lower idle also. thanks for the info.

eric
 
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