1999 Chevy Cavalier rough idle when returning to idle

Tiny
ERIKMARTIN2
  • MEMBER
  • 1999 CHEVROLET CAVALIER
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 145,000 MILES
Z24 2.4l

my problem is when driving down the road and come to a stop light or if I have to take my foot off the accelerator from freeway speeds to slow, then when I return pressure on the throttle the car stumbles a bit then jumps the rpm up t where I am trying to get them. It will also do it when coming to a stop, it will stumble and sometimes die. I have replaced all the filters and o2 sensors recently. The check engine light doesn't come on at all. I have read on the forumn similar issues but none exactly like miine. I have not changed out the spark plug "wires" yet but will if suggested so. Thanks for your time and help in advance.
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Monday, December 8th, 2008 AT 5:53 PM

9 Replies

Tiny
RHALL77
  • MEMBER
I would strongly look at the spark plug wires if they have never been replaced before. Another thing, when you had it scanned, do you know what cylinder was misfiring
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Monday, December 8th, 2008 AT 6:46 PM
Tiny
ERIKMARTIN2
  • MEMBER
Ok I will give that a try thank you. I haven't had it scanned yet. The issue really isn't a misfire it is a more of a performance issue when trying to return throttle after going to idle. It's more apparent when the car has been brought up to running temperature. I will try to replace the wires and let you know if that fixes it. Thanks again.
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Monday, December 8th, 2008 AT 7:09 PM
Tiny
RHALL77
  • MEMBER
Hi I was just checking up with you to see if you found anything out
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Monday, December 15th, 2008 AT 5:02 PM
Tiny
ERIKMARTIN2
  • MEMBER
I just replaced the spark plug wires/boots last night but no luck. It died today on my wife and it still will stumble when it returns to idle from time to time. I'm in a loss of what it is. Thanks for any help you may have.
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Monday, December 15th, 2008 AT 6:13 PM
Tiny
RHALL77
  • MEMBER
Have you had the fuel pressure checked yet
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Tuesday, December 16th, 2008 AT 5:16 PM
Tiny
ERIKMARTIN2
  • MEMBER
I have not checked the pressure but wouldn't seem to be the issue from what I can tell. The issue only happens when you release the throttle and let it fall to idle. It has great pickup and never has an issue at high rpms
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Sunday, January 4th, 2009 AT 9:10 PM
Tiny
RICHARD09
  • MEMBER
Tryin looking at the IAC valve to see if it is workin proper and the MAP sensor
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Sunday, January 4th, 2009 AT 9:22 PM
Tiny
ERIKMARTIN2
  • MEMBER
Finally think I found the problem with the help of you guys. My wife was driving home after dropping me off at work, and suddenly the car started missing and almost dying and the Check Engine Light flashing with the traction control light turning on and off with the engine light. So I got home tonight and pulled the code. I got a p303, cyl 3 misfire. So I pulled apart the ignition coil pack and swapped the two coils with the other and started looking at the new plug boots that I had bought and at the top of the spark plug to notice plug 3 had some odd tarnish on it. It was on the coil pack tip too. Upon further inspection found that the most inexpensive set of boots from Autozone mind you, was missing the metal spring that is used to connect the coil pack tip to the spark plug tip. So with that finally figured out back to the original problem at hand. So while I am trying to see if the light show was going to start again, the car started to chug getting back to idle. So I revved it more while it's in park and it seemed to continue to do so more and more. Perfect finally the car is having the problem while I can get under the hood. I started taking your idea about the IAC sensor and started feeling around near there and looking around it hoping I would hear or feel it making noise or something. As I was sitting there I could hear a hiss that sounded like a slight vacuum leak. So I looked and finally found a vacuum leak! YEAH! The vacuum hose from the intake manifold to the MAF sensor had rotted away and was collapsing on itself and had cracks all over it where it was beginning to leak. SOO, finally a long story short I will return in a couple of days to let you know if that was the problem and hopefully you can help pass the knowledge on for those having similar problems. Thanks again for all you help.
Cheers! Erik
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Wednesday, January 7th, 2009 AT 10:08 PM
Tiny
ERIKMARTIN2
  • MEMBER
Finally think I found the problem with the help of you guys. My wife was driving home after dropping me off at work, and suddenly the car started missing and almost dying and the Check Engine Light flashing with the traction control light turning on and off with the engine light. So I got home tonight and pulled the code. I got a p303, cyl 3 misfire. So I pulled apart the ignition coil pack and swapped the two coils with the other and started looking at the new plug boots that I had bought and at the top of the spark plug to notice plug 3 had some odd tarnish on it. It was on the coil pack tip too. Upon further inspection found that the most inexpensive set of boots from Autozone mind you, was missing the metal spring that is used to connect the coil pack tip to the spark plug tip. So with that finally figured out back to the original problem at hand. So while I am trying to see if the light show was going to start again, the car started to chug getting back to idle. So I revved it more while it's in park and it seemed to continue to do so more and more. Perfect finally the car is having the problem while I can get under the hood. I started taking your idea about the IAC sensor and started feeling around near there and looking around it hoping I would hear or feel it making noise or something. As I was sitting there I could hear a hiss that sounded like a slight vacuum leak. So I looked and finally found a vacuum leak! YEAH! The vacuum hose from the intake manifold to the MAP sensor had rotted away and was collapsing on itself and had cracks all over it where it was beginning to leak. SOO, finally a long story short I will return in a couple of days to let you know if that was the problem and hopefully you can help pass the knowledge on for those having similar problems. Thanks again for all you help.
Cheers! Erik[/quote:164e46c261]

Success!
It works perfectly now. Thanks for all you help with this problem.
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Sunday, January 11th, 2009 AT 10:27 AM

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