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Warm Idle about 650 RPM but act like it will stall

Tiny
PEPI-V
  • MEMBER
  • 2002 SATURN SL1
  • 1.9L
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 123,000 MILES
Saturntech9,

I have seen a lot of your responses to issues, so here is one for you. My daughters car, once warm likes to idle about 650 in drive. When we come to a stop and the idle starts coming down, it will drop down to almost 600 then shudder and back up to 650. It has new plugs (NGK's) and plug wires, new idle air control valve, throttle body cleaned and just recently a new ECT. The connector has been replaced before and looks to be good.

Thanks
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Sunday, September 10th, 2017 AT 7:10 AM

16 Replies

Tiny
SATURNTECH9
  • MECHANIC
  • 30,870 POSTS
Try this let it idle in park then get some carburetor spray or brake cleaner insert the straw into the nozzle and spray around where the intake manifold meets the head by the power steering pump area. If the engine stumbles or shuts off or rpm's increase then you you have a leaking intake manifold gasket, very common on those cars.
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Sunday, September 10th, 2017 AT 5:02 PM
Tiny
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Actually, I thought about that too and tried that, no change in rpm's.
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Sunday, September 10th, 2017 AT 5:09 PM
Tiny
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There is a short PCV hose that goes from the intake manifold to the valve cover, see if it is clasped or has holes in it?
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Sunday, September 10th, 2017 AT 5:24 PM
Tiny
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I will double check that, but I tried spraying carburetor cleaner all over the engine thinking a bad vacuum line, but did not notice any rpm changes.
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Sunday, September 10th, 2017 AT 5:26 PM
Tiny
SATURNTECH9
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Have you checked for codes in the computer yet?
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Sunday, September 10th, 2017 AT 5:33 PM
Tiny
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Yes I have, no codes. I should add, that we bought this car used a couple of months ago and the guy had replaced the cylinder head because something broke on the original one I thought he said for the cam. Otherwise the car runs great, just the idle dropping to almost killing after warming up If we have the AC on, it kicks the rpm's up a couple hundred and we have no problems at all. Turn AC off and the idle drops below 600 before it comes back up. Almost like the IAC is reacting slow. I could try another IAC, even though this one was new.
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Sunday, September 10th, 2017 AT 5:58 PM
Tiny
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This is for sure a SL1 not a L model Saturn?
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Sunday, September 10th, 2017 AT 6:44 PM
Tiny
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Yes, SL1.
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Sunday, September 10th, 2017 AT 6:52 PM
Tiny
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Okay, I have seen the four cylinder engine in the L 200 idle too slow and with the A/C on idle fine. Caused by needing a updated engine control module software.
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Sunday, September 10th, 2017 AT 7:05 PM
Tiny
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I suppose anything is possible, but I am wondering if the guy we bought the car from ever changed the ECM and used one from a L series.
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Monday, September 11th, 2017 AT 3:40 AM
Tiny
SATURNTECH9
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That would not plug in or work on that car. You could have a bad or carboned up idle air control valve, it is screwed to your throttle body. You could try lightly tapping on the idle air control and see if the rpm's rise to the normal level.
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Monday, September 11th, 2017 AT 9:16 PM
Tiny
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Okay, I did not get a chance yesterday to check anything, but I will try today. Thanks.
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Tuesday, September 12th, 2017 AT 4:00 AM
Tiny
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So it has been a while since I have posted anything and that kind of annoys me when I see people with problems and suggested answers and they never return for an update to let others know what worked or didn't work. So enough with my ranting and here we go.

I checked everything over and made sure no vacuum leaks. Couldn't find anything. As my daughter drove the car more and it started happening less and less. She never told me it did ever die on her. I don;t know if it just took a while for the new IAC to"sync" up with computer and find the right position or speed to which it reacted, but seemed to stop having issues. We have since sold the vehicle because we no longer needed it.

Saturntech9. Thanks for all your help and suggestions.
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Saturday, February 3rd, 2018 AT 1:23 AM
Tiny
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Your welcome the idle air control valve sets itself as soon as you start it after replacing it.
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Saturday, February 3rd, 2018 AT 1:33 AM
Tiny
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I know it should, but just seemed weird that the more we drove it the better it got. And by more we drove it, I mean almost over 1,000 miles.
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Saturday, February 3rd, 2018 AT 1:34 AM
Tiny
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Maybe you had water in the fuel tank and worked itself out. Thsts the worst and sometimes a pain to pin point that's what it is.
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Saturday, February 3rd, 2018 AT 8:52 AM

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