93 CIVIC IDLE SURGE

Are you getting a check engine light? It surges whether the engine is hot or cold. Have you had any work done to the intake manifold area? Another concern is the coolant level of the engine. If it is low or has air pockets this can cause the problem as well. Try bleeding the system. The idle air control valve can mess with this as well. The IAC senses the temp of the coolant and helps the engine regulate the fuel needed, much like the old carb and choke system. When it is out of whack the engine is confused on the mixture of fuel to supply. Another good possibility is the idle air sensor that is located opposite the throttle cam on the throttle body. Sometimes as they get older they stick and this is a cause as well.

[quote:e0518a8f51="Bruce Hunt"]Are you getting a check engine light? It surges whether the engine is hot or cold. Have you had any work done to the intake manifold area? Another concern is the coolant level of the engine. If it is low or has air pockets this can cause the problem as well. Try bleeding the system. The idle air control valve can mess with this as well. The IAC senses the temp of the coolant and helps the engine regulate the fuel needed, much like the old carb and choke system. When it is out of whack the engine is confused on the mixture of fuel to supply. Another good possibility is the idle air sensor that is located opposite the throttle cam on the throttle body. Sometimes as they get older they stick and this is a cause as well.[/quote:e0518a8f51] No he doesn't have a check engine light and it does surge no matter what the weather is. the only thing he has on there is a cheapy short ram intake from advance, but he had that on a while before this started. we bled the coolant and it is good. we still have to check the other sensors though. maybe get lucky.