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Old 11-17-2012, 10:05 AM   #1
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Another "chirp" thread - rough idle to boot

Gents,
I've had my CEL on for a while now as I literally just got it back after 7 months of being in the shop for transmission issues... lonnnnnng story.

Anyways, the codes are 1128 and 1130 and I've done some poking around, but haven't found any vacuum leaks that are obvious to me. I do know I have a few small exhaust leaks however and am planning on replacing manifold gaskets and all exhaust connections this weekend.

I have a problem though with a really rough idle and now a random "chirping" sound when the idle dips real low (like less than 500). I have THOROUGHLY cleaned my throttle body a couple times already and I didn't even really notice any difference at all. The car drives great except for when I slow down to a stop for a light or something and the idle starts bouncing like crazy, then tends to even out (around 600). Sometimes after it evens out it will do a VERY slow surge.. like every 5 seconds.

What I noticed today was that, if I had to stop pretty fast, or I came to a stop more quickly than just a "coast" to a stop, if the idle dipped real low, I would hear this "chirp" sound that sounded like it came from the driver's side (but doesn't everything when you're in the car ).

For shins and grins I popped the oil cap off and the car shot up to about 700 RPM steady and sounded really "healthy" if that makes sense. Didn't seem to surge at all. I heard the suction while it was removed. Same for the dipstick (heard the suction), but the dipstick had little effect on the idle.

What should I be chasing here? Should I admit defeat and let the dealership do a diagnostics on it so that I'm not throwing parts at it?

PS: The Secondary Air Injection System is a (troll) lol

...I can't seem to get ahead of repairs on this car. Was planning on doing my driver's window regulator today and that chirping sound scared me enough to turn around and park it (that and the hellacious traffic).
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Old 11-17-2012, 10:26 AM   #2
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Well, after posting, I did some more scouring of the web to see if anyone else has had this issue, and I found a post on Renntech (Squeak / chirp at low RPM - AOS related? - 986 Series (Boxster, Boxster S) - RennTech.org Forums) describing the same problem which turned out to be a loose spark plug!

Last weekend, I actually replaced one of the spark plug tubes and o-rings because of a small oil leak from it. Could this really be the culprit?? If oil got onto the actual spark plug, should it be replaced or can I simply take it out, clean everything real well and then replace and torque to spec? could this also cause the rough idle?

man if it is simply a loose spark plug...
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Old 11-17-2012, 07:40 PM   #3
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A loose plug is pretty common and often will chirp.
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