1997 Chrysler LHS High idle at all times

Tiny
JIM VANVALKENBURGH
  • MEMBER
  • 1997 CHRYSLER LHS
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 109,000 MILES
Recently my 3.5 engine idle speed started to increase. At first it went up a few hundred RPM, but lately has increased to 2200 RPM. At a cold start it will idle at 1500. Within 5 minutes the RPM will rise to 2200. I checked vacuum lines, cleaned the idle control motor, nothing I do seems to effect it. The check engine light comes on and then after a day or two it will go out for a day. I strongly suspect that too much air is getting into the manifold. I removed the air cleaner and blocked airflow to the plenum and still there was no change in RPM's. What am I missing?
Wednesday, February 13th, 2008 AT 12:13 PM

6 Replies

Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Try unplugging the MAF, and check the throttlebody for binding or worn shaft. Get the codes read! Autozone will do it free, then post the result. Even if the light is out, you have frezze frams data, it will tell you what conditions set the code, and what the code is!
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Wednesday, February 13th, 2008 AT 12:23 PM
Tiny
JIM VANVALKENBURGH
  • MEMBER
  • 2 POSTS
What do you mean MAF? I have an MAP sensor (manifold absolute pressure). Did you mean MAP?
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Wednesday, February 13th, 2008 AT 2:10 PM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
MAF=Mass airflow sensor it is in the intake air plenum, usually just above the air filter box, dont remove it just unplug it. Only as a test to see if your condition improves!
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Thursday, February 14th, 2008 AT 7:20 AM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
It might also be worth your while to buy a scanner, some are in the 30-40 dollar range and can read the P codes in all 96 thru 2008 cars sold in the USA.
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Thursday, February 14th, 2008 AT 7:23 AM
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Check the TPS and on the right strut tower ther is a relay for the manifold tuning valve. Unplug the IAC se what happens
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Friday, February 15th, 2008 AT 7:41 AM
Tiny
GARNZY
  • MEMBER
  • 13 POSTS
Serviced a car like that once, it turned out to be the big hose going to the pcv was cracked and just got bigger over time or once it heated up enough. Those hoses are thin walled and not very durable.
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Sunday, March 29th, 2009 AT 7:34 AM

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