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rpms keep suddenly dropping and going bak up constantly

 
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Old 08-24-2011, 09:48 PM
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rpms keep suddenly dropping and going bak up constantly

I got a 99 prelude H22 5spd. When I bought the car it had no issues, the motor was rebuilt to about 90k and the trans was untouchd at 180k. I noticed when the car is cold and I start it, the rpms drop rele fast from 3k to 1k and then bak up to 3k and dropping to 1k contstantly. My car has anaftermarket exhaust so you can only imagine how annoying it is in the morning so I'm forced to either keep turning the car on and off or to just drive it off until the engine warms up. I also noticed after driving the car a while and comming to a stop, the oil light starts to flicker and the rpms drop almost to the point of stalling at times even tho my oil isn't low..if anybody knows wuts going on please help me out. Thanks!
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Old 08-24-2011, 11:27 PM
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Re: rpms keep suddenly dropping and going bak up constantly

Sounds like a bad vacuum leak somewhere, but I'm not sure. As far as the rpms dropping sounds like an idle issue. Electrical or fuel related. What RPM's does your car normally idle at? Does it drop severely when you turn on your A/C. or use any powered features. I.E Windows and Sunroof?
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Old 08-24-2011, 11:48 PM
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Re: rpms keep suddenly dropping and going bak up constantly

check out the 5th gen research guide, there is a great idle problem thread, if you would have searched for it first you would have found it
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Old 08-25-2011, 03:49 AM
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Re: rpms keep suddenly dropping and going bak up constantly

sounds like you have a bad oil pump lol. The light is blinking.
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Old 08-25-2011, 08:49 AM
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Re: rpms keep suddenly dropping and going bak up constantly

Clean or replace your idel air control valve
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Old 08-25-2011, 09:05 AM
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Re: rpms keep suddenly dropping and going bak up constantly

yeah i doubt it's the fitv or iacv since his oil light is blinking, don't drive the car till you figure it out.
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Old 08-25-2011, 05:34 PM
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Re: rpms keep suddenly dropping and going bak up constantly

only when its cold the idle flickers? sounds like a fast idle to meeee, and the oil light flicking on and off even tho the oil isnt low souunds like a connection problem or the oil pressure switch is bad
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Old 08-25-2011, 08:43 PM
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Re: rpms keep suddenly dropping and going bak up constantly

iacv or fast idle valve. There is a good write up on here. Search idle problem thread and it will tell you how to fix it.
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Old 08-28-2011, 07:13 PM
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Re: rpms keep suddenly dropping and going bak up constantly

Check your vacuum hoses
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Old 08-28-2011, 07:22 PM
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Re: rpms keep suddenly dropping and going bak up constantly

Could be a bad IAC valve, I'd check that first
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