2004 Jeep Laredo Idle and RPM Running High in park

  • 2004 JEEP LAREDO
  • 6 CYL
  • 2WD
  • 140,000 MILES
We bought a 2004 Jeep Grand Cherokee Laredo with the 4.0 six liter engine that has 140,000 miles from a couple who lived in the country (so its all highway). When I bought it the check engine was on so I got one code, p0505. Went ahead and replaced the IAC then its threw the p0505, and p0123 so we replaced the throttle sensor. It did not fix it. Still getting both codes, neither part was OEM though. They were from O'reileys. The vehicle is normal in drive, but when its in park its running at 2000 rpm and if you touch the gas petal it jumps up to 3000 rpm and takes forever to come back down. I have cleaned the throttle body, and look for vacuum leaks. I do not know what to do now, please help, I need the car ASAP.

update - went back today and reset the computer, now I am only getting p0505 again. Going to try a factory IAC and see if that does not fix it. Please send any advice. Thanks - from dallas TX!
Do you
have the same problem?
Tuesday, July 20th, 2010 AT 9:26 AM

1 Reply

Check your pcv vavle also, a bad valve can cause a high idle also clean the bore in which the iac sits, in if you havent already, check the hose coming from the airfilter box for cracks and holes(causes high idle) also make sure there is no obstruction in the airbox, including air filter
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Sunday, August 29th, 2010 AT 2:14 PM

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