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1993 Honda Prelude unstable RPMs

Tiny
ROMANATOR23
  • MEMBER
  • 1993 HONDA PRELUDE
  • 4 CYL
  • FWD
  • MANUAL
  • 187,788 MILES
It starts when engine is turn on rpm going up and down from 1000rpm to 3000rpm when its warms up it goes a way but then I drive for 1min and check engine light comes on. During driving the rpm some times goes up and down also when in speed shift 1, 2, 3, 4, 5, no gas car jumps vhen rpm goes up and then slows when rpm goes down. Can you help me please. Thank you.
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Friday, February 26th, 2010 AT 10:06 PM

1 Reply

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Hi romanator23,

The engine is surging and possible causes are :

1. Low coolant level.
2. Clogged coolant hoses to IAC (Idle Air Control ) valve.
3. Faulty IAC or FITV
4. Leaking vacumns
5. Idling speed adjusted too high.
6. Faulty FITV ( Fast Idle Thermo valve)

Retrieve the trouble code.


https://www.2carpros.com/forum/automotive_pictures/192750_SCS92Prelude_5.jpg



Bridge the SCS and turn ignition switch ON. Count the blinking of the CEL and let me know what it says.
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Saturday, February 27th, 2010 AT 8:13 PM

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