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Unread 06-12-2013, 05:19 PM   #1
nikondsindent
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1989 YJ Wrangler 
 
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Wrangler 4.2 engine temp

i have a 89 wrangler 4.2 I6. i wanted to know what the normal operating temp is. my guage seems to only read up about 140-150. this seams really low.???

Would this cause my jeep to run richer because the computer is trying to put more fuel to get the jeep hotter?

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Unread 06-12-2013, 05:44 PM   #2
roadyrob
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you need a new thermostat, should be running around 190.
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Unread 06-12-2013, 07:13 PM   #3
Rproject
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Sounds like your thermostat is stuck open. I went with a 185 when I replaced mine.
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Unread 06-12-2013, 07:53 PM   #4
nikondsindent
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Would stuck open cause a more rich run less fuel economy since the car thinks its cold?
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Unread 06-12-2013, 08:29 PM   #5
Cashcrazy
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Mine sits on 160 and smells very rich. I'd like to know this also.
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Unread 06-12-2013, 08:47 PM   #6
nikondsindent
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Trying to pass smog, my first attempt failed at 8% CO when it should be .59%. >> Fixed carb and vac lines. Then second attempt brought me to a 2.8% >>> I believe the thermostat is stuck open making the jeep too cold telling the computer to burn more fuel to heat it up causing my rich status.
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Unread 06-12-2013, 09:40 PM   #7
packdog
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Yes

Yes it can affect fuel economy. If the computer thinks the temperature is low it will add more fuel to the mix. I doubt the difference between 140 and 180 would make a noticeable difference in gas mileage though. However, since it takes longer to warm everything up when the thermostat is stuck open, you would be running in a richer condition for a longer period of time. Hope that makes sense.

That is actually how some if those gadgets that claim to improve fuel economy work - they are just a resistor that gets installed in the temperature sensor circuit (usually intake air temp if the vehicle has one) to feed a false reading to the ECU.
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Unread 06-13-2013, 06:47 PM   #8
87laredo
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Quote:
Originally Posted by roadyrob
you need a new thermostat, should be running around 190.
X2 I just purchased a new OE thermostat and water pump and the motor now runs at 190 to 200.
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