Mechanics

WHEN SITTING IDLE

1991 Honda Prelude

Engine Performance problem
1991 Honda Prelude 4 cyl Two Wheel Drive Manual 149000 miles

when car is sitting idle engine goes up to 1600 rpm than back down to 1100 rpm over and over. What could be wrong with it?
Avatar
Jkerr1957
August 17, 2010.



Hi jkerr1957,

The idling system has a fault and it could be: 1, Vacumn leakages,
2. Faulty Fast Idle Thermo valve.
3. Lack of coolant.
4. Clogged coolant hoses.
5. Idling speed adjusted too high.

KHLow2008
Aug 21, 2010.