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Old 04-04-2020, 10:34 AM   #1
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Join Date: Apr 2020
Location: scotland
Posts: 3
Porsche Boxster 986 2.7 2000YR hunting / rough idle

Hello, this is my first post in the forum, I am currently at trying to solve the following issue with my Boxster:

From cold: the revs will sit just over 1000 (1100-1250) then after about a minute will drop below to about 750/800 which is normal I think.
At the 750/800 stage the car starts to hunt and run rough at idle approx 500 RPM variance, which feels and sounds like a light misfire. Even when the car is fully warmed up out on a drive sitting at idle this will still occur. Applying the throttle back to the 1100 range will stop the symptoms. No Check engine light or any codes.

so far to try rectify the issue I have:

fitted new spark plugs
cleaned the throttle body (which was dirty)
cleaned the MAF (looked brand new before cleaning) I've unplugged the MAF sensor while running and it made no odds, still rough.
Changed the AOS (Air Oil Separator)
Checked for vacuum leaks (can't find any)

Other than the symptoms at idle the car runs as it should the rest of the drive. I know similar threads have been posted before but I have read as many of those as I can posting myself was a last resort! Any help would be greatly appreciated thanks.

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Old 04-08-2020, 02:26 PM   #2
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Join Date: Jun 2016
Location: Arizona
Posts: 376
Vacuum leak, maybe coil pack (s). So many possibilities.
2002 Boxster S - NHP 200 Cell Headers,test pipes,Borla CatBack,Competition Plenum,74 mm TB, EVOMS Tune,Tarett UDP,Eibach Swaybars,BIlstein PSS9s,TuneRS rear toe links,wheel studs,15 mm wheel spacers on all 4,EBC yellow stuff pads,Sebro rotors, EBS oil baffles,160 deg Thermostat,2 quart Accusump,full filtration remote oil filter,rad fan switch,custom gauge/switch plate, Race Capture data logging, 90K miles
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Old 04-08-2020, 02:37 PM   #3
1998 Boxster Silver/Red
Join Date: Sep 2017
Location: 92262
Posts: 2,134
Time for a smoke test. Sounds like when you're driving... and the Rs are up... the vacuum issue is settled. You hit idle... it starts hunting for vacuum.

The general rule of thumb is to consider what last you were working upon, and before you attended to your list of fixs, and see if a line somewhere didn't break... or become detached.

Report back when you've solved the problem.

And, welcome to the forum!

1998 Porsche Boxster
1986 BMW 325es
2012 Ford Edge Sport
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hunting , idle , rough

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