Idles up and down

1997 NISSAN TRUCK
177,000 MILES • 2.0L • 4 CYL • 4WD • MANUAL
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UHSNOEBIRD
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My truck idles up sometimes to 1,500 rpm's and then down and sometimes quits. It doesn't show any check engine lights . I know the distributor cap, rotor button, plug wires, gas filter and so on are good.
I was thinking it might be the idle control valve I call it. I don't know the technical name for it .
Does the idle control valve give me a check engine code if it's bad or does the IAC give a code is it goes bad ?
Dec 25, 2019 at 7:03 AM
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KASEKENNY
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More than likely you are correct that it is the idle control valve. Your specific component is called the idle air adjusting unit.

If it were me I would go ahead and replace it. You can clean them but again, they are cheap enough I would just go with new one and then clean the old one so you always have a spare.

https://www.2carpros.com/articles/idle-air-control-valve-service

Let me know if you have questions. Thanks
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Dec 25, 2019 at 1:11 PM
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UHSNOEBIRD
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I don't have any check engine lights on. plus I checked for codes with my diagnostic tester and it showed none.
I've been told this might be the problem this part fuel injection thermostat in this web link:
https://www.carid.com/original-equipment/fuel-injection-thermostat-mpn-1639112g00.html?singleid=1795967990&url=4904360#warranty
Dec 25, 2019 at 8:13 PM
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KASEKENNY
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It could but if you monitor the fuel pressure you should see a change that corresponds with the surging if it is fuel related. If you don't then it is air control related.
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Dec 26, 2019 at 11:15 AM