93 LX 2.3L low coolant temperature

Dloudin87

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Jan 25, 2020
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I have a 93 lx 2.3L. 43k miles. I have flused and back flushed system. Replaced water pump, thermostat, temp sensor, lower hose and radiator cap. Coolant temp will reach normal when sitting at idle. Soon as I start driving it. It drops down to 130. Seems to go into limp mode. Code I got off jumping the port was 21 (coolant temperature out of range). I can't figure this out. Can anyone help??
 
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Dloudin87

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Jan 25, 2020
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Charleston West Virginia
I only knew of the coolant temp sensor that is on the heater core hose. There is another? Do you know the location? And the thermostat didn't seat snug in the block and I'm wondering if that could have something to do with it.
 

junkyardwarrior

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Jan 10, 2011
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When you replaced the thermostat, was it the correct one? These engines are notorious for running "cold" in the winter.

the theremostat housing itself is a common cause. Was that replaced? When you put the stat in, did you index the thermostat so that it locks tight against the housing? In other words, stuff it in, then spin it until it seals against the housing as best that it can. If it's got a bleed valve in the stat (some do some don't), make sure it's pointing up (12:00), and that's all you can do.

When installing the thermostat, the two little legs need to make contact with the block. This forces the stat into the housing to seal it off. If it's not sealing against the housing, it will leak past and never warm up. I have had to throw an o-ring in behind the stat gasket (between the housing and rubber stat gasket) as a spacer to seal it up.

You will get a code for ECT if the engine is not up to operating temp (160+).
 
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91TwighlightGT

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I took this from another site that I can't link to here...

Are we talking temp gauge or what turns the fans on? Yours is a 8 plug engine. If so the gauge sending unit is in block under intake. The one that turns the fan is in the upper intake between #2 and #3 injector. The is also the ECT sensor for the computer. The computer tells the IRCM on passenger fender when to pull relay in and out. Maurice
IRCM info.
JR's Place - Ford IRCM Schematic & Troubleshooting
92 Mustang wiring diagram. Second page is diagram for the IRCM connections.
http://www.rothfam.com/svo/reference/92-93Mustang.pdf
It sounds like you replaced the ECT sensor. I think junkyardwarrior is on the right track, though - faulty or improperly installed thermostat. The only thing I don't like is that if the thermostat is stuck open it should take a very long time to heat up at idle. If it is leaking past as he is describing, though, I imagine that it could heat up at idle because there is low pressure from the water pump to push a large volume of coolant past the thermostat - once you get rolling, the increased pressure forces enough past that the car cools down quickly.
 

Dloudin87

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Jan 25, 2020
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Charleston West Virginia
I have some diagrams from another forum and I don't have a sensor between the injectors. And haven't seen one on the block. I just installed a Motorcraft thermostat. This makes 2nd one Ive put in with no change. I have an aftermarket temp gauge im going to install today so I can see what is going on. Once I know for sure whether I'm overheating or under heating I will report back
 

junkyardwarrior

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Jan 10, 2011
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Well....interesting and ironic.

Mine is exhibiting same symptoms. Wont' really warm up. Runs about 140 all the time unless sitting still. Replaced thermostat, installed an o-ring between stat and housing, verified it's sealing against the housing because I can't blow through it. Motorcraft 192.

Found a BNIB robertshaw 192, ordered it and will try next week.
 

Dloudin87

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Jan 25, 2020
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Charleston West Virginia
In the end. My ECM needed reset. And I put some cardboard in front of the radiator. Now I am gaining temperature like I should be. I was told that these things are hard to get warm in colder weather. Maybe give the cardboard trick a try and see what happens!
 

vristang

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The dash gauge should be thought of as an indicator on these engines, not as a thermostat... Both of my 2.3's have always indicated cooler than what the actual engine temps were...

Get the data from the ECT sensor before concluding that your coolant temps are too low...
 

junkyardwarrior

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Jan 10, 2011
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Robertshaw thermostat did in fact help mine. It now gains temp quickly.

But....

the gauge still shows "low" temp all the time. So out of curiousity, I pulled the kick panel and accessed the computer. Back probed the ECT pins and watched the ECT signal; it is in fact getting hot (190); however the gauge doesn't really read hot. Probably has something to do with where Ford placed the sensor, may have cool water there-OR might be a wiring issue, dunno. Aint had time to fiddle with it.