Just finished swapping out the standard 1.5 for a 1.6 out of an si and the engine will idle fine sometimes and then for no reason rev to about 1500 and stay there and go back to normal idle after a minute or so. Also im using all the 1.5 dpfi also. The old engine did not do this just wore out and also no check engine light has come on. Any ideas?
Idle problems
- Thread starter ttpruden
- Start date
i had a 1990 civic dx and it sat for 3 years and i bought it for $150 got it running but idle would stay at 1500rpm then some times go back down to 900rpm i was told it was the coolent temp valve cause when the car is cold the valve stays open to keep the engine reving at 1500rpm and when the coolent reaches a certain temp the valve closes and the rpms drop to 750rpm that was my guess. or could be a valcum hose?