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Old 03-14-2007, 06:31 PM   #1
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Default Sudden idle drop

When I sit at a stop light, or train or whatever I notice that my car will all of a sudden drop in rpm'*. My car idle'* right about 700 and when this happens it drops to about 400 rpm'* and kind of sputters. It has done this since I bought the car, but it'* kind of aggravating.

Any clue what this may be? Or what may be causing it? Should I be worried?
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Old 03-14-2007, 06:36 PM   #2
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Sounds like a really dirty IAC passage. Have you replaced your leaky LIM gaskets yet?
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Old 03-14-2007, 06:39 PM   #3
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That turned out to not be a problem. My LIM is fine according to the dealership.

It has been doing it since I bought the car with 57,000 miles on it. I now have 71,500 miles on the car and this problem has not worsened. It doesn't do it everytime I'm at a light, just sometimes.
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Old 03-15-2007, 12:12 AM   #4
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Is your voltage dropping when this happens?
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Old 03-15-2007, 01:09 AM   #5
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Hmmm.... and are the plugs/wires/coils etc all original?

Edit: after reading this post... http://www.bonnevilleclub.com/forum/...ic.php?t=73925

it made me wonder if you noticed the same conditions... rainy weather? belt squeal?
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Old 03-15-2007, 01:48 AM   #6
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well mine does that too, i will be investigating this summer...

my thoughts on it are most likely dirty sensors. I would clean the MAF, make sure your O2s are good, clean IAT, and make sure the car is tuned up.
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Old 03-15-2007, 08:13 AM   #7
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My first suggestions would be to clean the MAF and IAC. Both can be removed w/o much fuss. (couple of screws). After that, pull a plug or two and review them for needing to be replaced. At 71K they are probably at minimum in need of regapping.

From there, suggestions would be to remove the TB and fully clean it (do not clean on car). Consider plugs and wires.
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Old 03-15-2007, 08:57 AM   #8
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Default Re: Sudden idle drop

Quote:
Originally Posted by Pearl_bonnie02
When I sit at a stop light, or train or whatever I notice that my car will all of a sudden drop in rpm'*. My car idle'* right about 700 and when this happens it drops to about 400 rpm'* and kind of sputters. It has done this since I bought the car, but it'* kind of aggravating.

Any clue what this may be? Or what may be causing it? Should I be worried?

I have the same exact problem and have yet to find out what it is. I am going to clean everything (MAF & IAC) again, and if that doesn't work, replace the o2'*.

http://www.bonnevilleclub.com/forum/...ic.php?t=73797
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Old 03-15-2007, 10:00 AM   #9
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DMLeonard..

I wouldn't suggest the O2'* unless you've had it scanned and know they are slow to respond. An O2 shouldn't cause idle issues.

Vacuum leaks
Not seeing actual air at intake (maf)
IAC (Idle air control) leaking
PCV possibly not being sealed
Plugs
Wires
Dirty air filter

These are the items where you probably want to concentrate your attention.
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Old 03-15-2007, 11:24 AM   #10
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Had the car looked at after work yesterday...

No Vacumm Leaks
Plugs and Wires are fine
O2 Sensors are good
New Air Filter

Basically the guy said he finds no reason for this to be happening. I'm going to wait and see when it does it again if my voltage goes down. I notice I get a similar feeling when I roll down all 4 windows at the same time. And it seems to be worse in the summer than now due to me running the air.
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