Faulty Coolant temp sender
03-12-2022, 08:33 AM
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Faulty Coolant temp sender
Can a faulty temp sender cause idling issues on a 91 z28 5.7 tpi I've unplugged the sender and noticed a difference in idle but thought the sender didn't communicate with the ecm?
03-12-2022, 08:37 AM
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Re: Faulty Coolant temp sender
There are 2. One for the ecm, one for the gauge. Completely separate circuits. Depends on which one you unplugged.
03-12-2022, 09:43 AM
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Re: Faulty Coolant temp sender
I think if you unplug the sensor it'll put the computer into open loop.
The change in idle then would not necessarily be due to a bad coolant sensor. It may be due to the ECM no longer trimming the fuel poorly due to some other malfunction.
In closed loop the ECM will react to a malfunction by trimming the fuel differently than it would if everything were normal. So the poor fuel trim could be what's causing the idle issue when the coolant sensor is plugged in and the ECM is in closed loop.
The change in idle then would not necessarily be due to a bad coolant sensor. It may be due to the ECM no longer trimming the fuel poorly due to some other malfunction.
In closed loop the ECM will react to a malfunction by trimming the fuel differently than it would if everything were normal. So the poor fuel trim could be what's causing the idle issue when the coolant sensor is plugged in and the ECM is in closed loop.
03-12-2022, 11:28 AM
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Re: Faulty Coolant temp sender
The one in the head isn't the [mrspock]sen-sore[/mrspock]. At least not from the factory. It's the temp gauge sending unit.
The [mrspock]sen-sore[/mrspock] has 2 wires; yellow & black. The gauge sending unit has only 1; dark green.
The gauge sending unit is not connected to "the engine" or the ECM in any manner way shape form or fashion. It is totally unrelated to "run". It strictly only works the gauge, just like since the 50s. In fact, except for the threads, it's the same as it's been since the 50s.
Correlation is not causation.
The [mrspock]sen-sore[/mrspock] has 2 wires; yellow & black. The gauge sending unit has only 1; dark green.
The gauge sending unit is not connected to "the engine" or the ECM in any manner way shape form or fashion. It is totally unrelated to "run". It strictly only works the gauge, just like since the 50s. In fact, except for the threads, it's the same as it's been since the 50s.
Correlation is not causation.
03-12-2022, 12:38 PM
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Car: 88 GTA Notch/01'WS-6 VERT
Engine: 5.0 LB-9/5.7 LS-1
Transmission: 700R-4/4L60
Axle/Gears: borg warner 3.27's
Re: Faulty Coolant temp sender
The one in the head isn't the [mrspock]sen-sore[/mrspock]. At least not from the factory. It's the temp gauge sending unit.
The [mrspock]sen-sore[/mrspock] has 2 wires; yellow & black. The gauge sending unit has only 1; dark green.
The gauge sending unit is not connected to "the engine" or the ECM in any manner way shape form or fashion. It is totally unrelated to "run". It strictly only works the gauge, just like since the 50s. In fact, except for the threads, it's the same as it's been since the 50s.
Correlation is not causation.
The [mrspock]sen-sore[/mrspock] has 2 wires; yellow & black. The gauge sending unit has only 1; dark green.
The gauge sending unit is not connected to "the engine" or the ECM in any manner way shape form or fashion. It is totally unrelated to "run". It strictly only works the gauge, just like since the 50s. In fact, except for the threads, it's the same as it's been since the 50s.
Correlation is not causation.
I thought this as well just double checking thank you for the clarification
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