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Slightly rough idle in park. Anybody have this problem also?
Posted: Mon Aug 29, 2011 12:53 pm
by 2000GreySSEi
I have had this problem ever since I bought the car. In park or neutral (when there no load on the engine) the motor idle a little rough, and the engine shakes. However when the engine in loaded in gear, the idle smooth and the engine doesn't move at all. The car itself runs perfectly. Out of every 3800 powered car I've had (every car I had really lol), I have never had one idle this smooth. It idles so smooth at a light that it feels like the engine is off. It's just in park idle has some misses. The sparks plugs have less than 10k miles on it (AC Delco Iridiums), and I just took off those crappy Bosch Wires the previous owner had on there, and put some good NAPA Belden blues on (changing the back was a Major PITA btw). I know the reason the motor shakes is because the front marshmallow mount is bad, but can that cause it to idle rough.
Re: Slightly rough idle in park. Anybody have this problem a
Posted: Mon Aug 29, 2011 6:55 pm
by nos4blood70
I used to have the same EXACT problem, but when I installed a new front mount the problem went away. :O
Re: Slightly rough idle in park. Anybody have this problem a
Posted: Mon Aug 29, 2011 7:31 pm
by Bing
Ever clean the throttle body yet?
Thinking along the lines of the IAC, but definitely the whole thing if you've never cleaned it before.
Make sure you take out the MAF sensor (expensive) and clean it separately with MAF cleaner or rubbing alcohol and a Q-tip (very gently).
Re: Slightly rough idle in park. Anybody have this problem a
Posted: Mon Aug 29, 2011 10:57 pm
by 2000GreySSEi
Oh Duh. I forgot all about the throttle body. I am going to try to clean it tomorrow.
Re: Slightly rough idle in park. Anybody have this problem a
Posted: Tue Aug 30, 2011 6:06 am
by Bing
Before you start make sure that you have a throttle body gasket. You'll also need a security torx bit set . If you want you can replace the security torx screws with allen head or regular torx, makes the cleaning process that much easier next time.
When you clean the IAC (idle air control) make sure you lightly lube the plunger when you're done cleaning it. Just don't try to push it in or move it around. I would spend some time cleaning out the passages for the IAC to.
What ever you do don't use anything abrasive or try and scrape anything out of the throttle body. Let the solvent do the dirty work.
Make sure that you put everything back together right or
it'll give you fits when you think you're done. The throttle position sensor has to have tension on the spring, just make sure it goes back the same way.
Here's a video on how to correctly install the TPS.
http://s675.photobucket.com/albums/vv11 ... nt=TPS.mp4
Basically take your time and take notes or pictures to help yourself out.