Rough Idle with an odd symptom

Re: Rough Idle with an ndd "pmptom

No suggestions> Wi,d carb cleaner srt any of the sensors in the TB?

I have a 98 XJ 4.0 Auto. In the morning starting it it runs fine for a few mins, and by time Im back inside I can hear it start to idle rough. Now during the day for the last couple of days it's been running fine, but if I get out at a store and come back 10 mins later, it starts up fine and then has a rough idle. Not jumping up high and then back down, but running normal than dropping out. Give it a few mins and a little gas and it jumps back to normal, like it never happened. I know, search and I can read all about it. I searched, but I have a symptom that isnt noted in other rough idle threads. I can hear it sucking in a huge amount of air when it's doing this. I have a rustys airtube, so its really noticable. Its not sucking the air in from idling up, either. Ive tried some gumout, gonna try some drygas tomorrow, and probably some TB cleaner. Any other suggestions?

98XJSport said:

No suggestions? Will carb cleaner hurt any of the sensors in the TB?

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It should not hurt anything on the inside.
I would also suspect a failing coolent temp sensor, your engine is warm but the temp sensor thinks it's still cold.

M A T manifold air temp sensor-may be dirty.Remove and clean,carb cleaner is fine.
Located on the top of intake manifold,1 wire plug,Yes there is a lot of suckage noise from the Rustys air tube--I have one so I know the noise.
Wayne

It could also be the Rusty system because you no longer have any intake air heat and that will cause rough idle and low air temp.

Ive already replaced the coolant sensor for unrelated reasons. Its done it both when the engine is hot and when it is cold. Ive had the airtube for over a year now, with no problems. The amount of air sounded like im revving the engine, but the engine wasn't revving... Will try hosing stuff down during lunch break. Thanks

langer1 said:

It could also be the Rusty system because you no longer have any intake air heat and that will cause rough idle and low air temp.

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IIRC there has been no heated air since the switch from the renix system.
Wayne