Rpm falling below idle at stops

Wyeth Bernardin

Wyeth Bernardin

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Joined
Feb 2, 2017
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10
Location
Bainbridge Island, WA, United States
Hi, I have a 97 Wrangler 2.5 and recently when I stop or slow down suddenly the rpm will fall below idle. It drops to about 500 rpm. I have read that it could have something to do with the exhaust but I don't want to go tearing apart the engine to find nothing. Looking for a quick fix because this car is my daily driver! Also note the temperature outside has been around 30-40 degrees, not sure if that could be affecting it as well. As it stands I'm not super worried about it because it doesn't seem to affect the overall performance of the vehicle. Any thoughts? Thanks.
 
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Mine idles at about 500 and 600. Your water temp 30 to 40? You sure about that? 4.0l or 2.5l? Is it idling rough hesitating?
 
i think someone had a problem similar to this not too long ago and he cleaned his TPS and that sorted it.

there's a link on here somewhere how to do it.

otherwise like Raymond said it could be vacuum leak, check your headers, from underneath, check all the joins and welds if you find big cracks, holes or worse.. this could be your problem.
 
Wyeth Bernardin said:
Hi, I have a 97 Wrangler and recently when I stop or slow down suddenly the rpm will fall below idle. It drops to about 500 rpm. I have read that it could have something to do with the exhaust but I don't want to go tearing apart the engine to find nothing. Looking for a quick fix because this car is my daily driver! Also note it has the temperature has been around 30-40 degrees, not sure if that could be affecting it as well. As it stands I'm not super worried about it because it doesn't seem to affect the overall performance of the vehicle. Any thoughts? Thanks.
Click to expand...
Not sure about the 30-40 degrees..?? Try cleaning your idle air control (IAC). It's easy, quick and cheap to do.
 
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Wyeth Bernardin said:
Hi, I have a 97 Wrangler and recently when I stop or slow down suddenly the rpm will fall below idle. It drops to about 500 rpm. I have read that it could have something to do with the exhaust but I don't want to go tearing apart the engine to find nothing. Looking for a quick fix because this car is my daily driver! Also note it has the temperature has been around 30-40 degrees, not sure if that could be affecting it as well. As it stands I'm not super worried about it because it doesn't seem to affect the overall performance of the vehicle. Any thoughts? Thanks.
Click to expand...
Check this thread out. Jerry has a great write up on cleaning the IAC.
https://wranglertjforum.com/threads/idle-issues.468/
 
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JP98 said:
Not sure about the 30-40 degrees..?? Try cleaning your idle air control (IAC). It's easy, quick and cheap to do.
Click to expand...
I'm assuming he means 30-40 degrees outside temp.
I would start with cleaning the IAC. Quick and easy. There is a write up in the how to's here if you don't know how to do that.
 
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Wyeth Bernardin said:
Hi, I have a 97 Wrangler 2.5 and recently when I stop or slow down suddenly the rpm will fall below idle. It drops to about 500 rpm. I have read that it could have something to do with the exhaust but I don't want to go tearing apart the engine to find nothing. Looking for a quick fix because this car is my daily driver! Also note the temperature outside has been around 30-40 degrees, not sure if that could be affecting it as well. As it stands I'm not super worried about it because it doesn't seem to affect the overall performance of the vehicle. Any thoughts? Thanks.
Click to expand...
Updates? Curious to hear if anything worked out in this case?

Also on a side note...Bainbridge Island, man i'm jealous. Great area!
 
JP98 said:
Not sure about the 30-40 degrees..?? Try cleaning your idle air control (IAC). It's easy, quick and cheap to do.
Click to expand...
X2, your idle issue sounds very much like it could be caused by nothing more than a dirty IAC. IACs don't usually need to be replaced, they can normally be restored to 100% operating condition by simply cleaning them.

If your engine isn't warming up enough, the wrong/too low of a temperature thermostat might have been installed by a clueless previous owner or mechanic. The thermostat must have a 195 degree temperature rating, don't use 160-185 temperature thermostats. Avoid too the use of any thermostat that is a "fail-safe" which only means it likes to fail in the open position. A Stant SuperStat 195 degree thermostat is a great choice.
 
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