engine revving after driving???

mitsumotors · Feb 16, 2009

my 91 4.0 is acting strange lately. i installed a vac gauge a while back so i could check for problems and still have it mounted in the cab. when i start up the jeep it idles around 800rpm and is at about 17 on the vac gauge. but after driving for a while when i stop and put it in park it revs up to around 1200rpm and is sitting at about 21 on the vac gauge. i have no idea what could be going on here. anyone?

mitsumotors · Feb 16, 2009

help please

mitsumotors · Feb 16, 2009

someone's gotta have at least a little info that might help me.

winterbeater · Feb 16, 2009

IAC sticking open too high or vacuum leak? Test for leak with unlit propane torch checking in suspect areas like intake manifold.

89xj · Feb 17, 2009

x2, clean the iac and while your at it, clean the throttle body .

mitsumotors · Feb 17, 2009

thanks guys

rydizzy · Feb 17, 2009

Just replace the IAC. They're inexpensive.

89xj · Feb 17, 2009

rydizzy said:
Just replace the IAC. They're inexpensive.

cleaning is even cheaper. why replace if its just gunked up?

rydizzy · Feb 17, 2009

I'm just saying I would just replace it. I like things new.

lawsoncl · Feb 18, 2009

rydizzy said:
I'm just saying I would just replace it. I like things new.

Still need to clean the bore it sits in anyway. I don't really consider $50 to be cheap when 10-cents of carb cleaner and a toothbrush are all it needs. Its not like a bad one will strand you anywhere like the CPS sensor.

winterbeater · Feb 18, 2009

rydizzy said:
I'm just saying I would just replace it. I like things new.

Everybody has a different way. I like things old. That's why I have an XJ. If I can clean it, glue it, or weld it without spending money, I feel like I accomplished something cool. It's like a challenge to me. And I don't trust new parts until they have passed the test of time.:sunshine:

rydizzy · Feb 18, 2009

lawsoncl said:
Still need to clean the bore it sits in anyway. I don't really consider $50 to be cheap when 10-cents of carb cleaner and a toothbrush are all it needs. Its not like a bad one will strand you anywhere like the CPS sensor.

I'm not sure where you saw one for $50. I got new spark plugs and wires, new distributor cap and rotor, and a new IAC all for $50.

89xj · Feb 18, 2009

rydizzy said:
I'm not sure where you saw one for $50. I got new spark plugs and wires, new distributor cap and rotor, and a new IAC all for $50.

i will do some searching, but the last time i checked, i think the IAC for my 89 was around $30. not expensive, but i see it as a maintenance item that is cheap to clean.

did a quick search at advanced auto and the cheapest they showed was $49

http://shop.advanceautoparts.com/Pr...=BOR&MfrPartNumber=21771&PartType=506&PTSet=A

engine revving after driving???

mitsumotors

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