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pinetreeporsche
Samba Member
Joined: June 11, 2009
Posts: 752
Location: Falls Church, VA
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 Posted: Fri Jul 27, 2018 1:24 pm Post subject: High (and higher) revs at idle- comes and goes |
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A couple of weeks ago it would idle at about 2100 rpm. Not hard to put up with, and sometimes was 'normal'. If I shut off the air conditioning it would always drop to 800. I figured in 2 months I wouldn't be using the AC, so wth- just use the switch when needed to get back to 800. THEN: 4 days ago it started idling at about 3000, regardless of the compressor switch. And by later that day it was topping 4000! I had to kill the motor if I get caught by a red light, and if I was in modest traffic that slowed down I had to throw in the clutch, maybe shift to a lower gear so I could keep my speed down. Sure takes the fun out of city driving!
Has anyone seen something like this (like either of these two distinct conditions!)? Any useful hints appreciated. |
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Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50331
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| Posted: Fri Jul 27, 2018 3:52 pm Post subject: Re: High (and higher) revs at idle- comes and goes |
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| You need to go around and pinch each hose going into the plenum in turn or disconnect them and plug the corresponding nipples in the plenum. |
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E1
Samba Member
Joined: January 21, 2013
Posts: 6520
Location: Westfalia, Earth
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| Posted: Fri Jul 27, 2018 5:25 pm Post subject: Re: High (and higher) revs at idle- comes and goes |
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Sticking throttle?
Vacuum leak?
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
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Subtracting weight makes you faster everywhere."
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tencentlife
Samba Member
Joined: May 02, 2006
Posts: 10075
Location: Abiquiu, NM, USA
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| Posted: Sat Jul 28, 2018 7:13 am Post subject: Re: High (and higher) revs at idle- comes and goes |
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Well if it's Digifant it's probably a dirty sticky Idle Speed Control Valve, the tipoff being idle speed rising when the AC is switched on, which is easy to confirm by simply pinching off the ribbed J-shaped rubber hose going to it next time it acts up, and is also easy to fix by removing the valve and cleaning it out with carb cleaner and compressed air while activating it with 12V, it has no polarity, but the OP forgot to do readers the courtesy of putting his year/model in a sig line, so we just don't know.
How was that?
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pinetreeporsche
Samba Member
Joined: June 11, 2009
Posts: 752
Location: Falls Church, VA
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| Posted: Sat Jul 28, 2018 1:15 pm Post subject: Re: High (and higher) revs at idle- comes and goes |
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Sorry to omit the year- it's an '87, a 2.1 (rebuilt as 2.2 several years ago).
E1: likely not a sticky throttle, as it sometimes comes and goes within 5 sec while sitting at a light. Will look for vac leak.
10cent- sounds like a good tail to follow name Idle control valv.e. I'll give it a look; thanks |
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