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1999 Cavalier Z24 runs, but idles funny?


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1999Z24
User
1999Z24 profile image

Feb 26, 2011, 12:21 AM

Post #1 of 4 (2988 views)
1999 Cavalier Z24 runs, but idles funny? Sign In

i have a 1999 Cavalier Z24 with the 2.4L motor with an automatic transmission with 157,xxx miles.
the check engine light is NOT on.

it starts, no problems. it runs and drives great when its cold, but when it warms up, this is what happens. when the motor warms up, it about dies, but then idles up. sometimes it does die though. when im driving, il push the petal softly, and it will idle down, and almost die. i let off the gas, the RPS's go back up to where they were. if i tap the gas over and over, or step on it, the RPM's will go up, and it runs fine, and DEFINETLY has power at higher RPM's. it NEVER does this when its cold. ive Changed all 4 fuel injectors with used fuel injectors, but i know the injectors were fine cuz the motor i took them out of, ran completely fine, just had a spun rod bearing. also put in idle positioning sensor, air filter sensor, and some other sensor on the front of the carb from that other motor, BRAND new fuel filter, new spark plugs, and ran 2 bottles of sea-foam through it. seems like all of that helps a LITTLE at the beginning, but then it keeps doing it. my next guess is the Catalytic converter? but i REALLY dont want to change that, and it ends up not being the problem(its NOT cheap) if ANYONE has had this same problem, or has a suggestion, please let me know. i have another motor that has a spun bearing, so i can cop parts off that until i find whats wrong. thanks.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 26, 2011, 6:12 AM

Post #2 of 4 (2981 views)
Re: 1999 Cavalier Z24 runs, but idles funny? Sign In

  You may have a bad IAC ( idle air control) but try eliminating any vacuum leaks and cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



1999Z24
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Feb 26, 2011, 6:22 AM

Post #3 of 4 (2976 views)
Re: 1999 Cavalier Z24 runs, but idles funny? Sign In

i googled the IAC to see what it looks like, and thats the other sensor i was talking about that i also changed, but didnt know what it was called. first, me and my uncle carefully cleaned up the current IAC in it, and put it back on, but it didnt do anything. then we changed it, and it still did this. i tried cleaning the intake with my uncle with a rag too, but that didnt do anything neither. i guess il try cleaning up all up 1 more time, and maybe i'll hit something i never cleaned before. thanks for the suggestion.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Feb 26, 2011, 6:25 AM

Post #4 of 4 (2974 views)
Re: 1999 Cavalier Z24 runs, but idles funny? Sign In

The back of the throttle plate and the bore in that area are important.

On a side note, I hope you haven't tried to adjust the base idle screw because that will cause this also.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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