91 Si - Surging Idle

[underdog3]

I've been all over this forum and done quite a few searchs. I've read some posts related to this problem, but I think I have something different.

When the engine is hot, and the clutch in, the engine surges from about 1k to 1.75k holds there for a sec, then drops.

There are two situations where the surging dosen't happen.

1. when I've pulled the vacuum hose from the fast idle soloniod valve and cover its vacuum pressure ( I don't think that when the engine is warm it should be pulling vacuum)

2. when I pull the engine temp sensor cable from the sensor (under distributor) turns the check engine light on.

The check engine light isn't on, unless I pull the temp sensor cable.

any ideas??

[optimuscivic]

http://www.automotiveforums.com/vbul...d.php?t=199271 go to this thread. seems like these civics are always having idling problems.

[underdog3]

Well I found the problem. Contrary to all who have posted this problem before, mine was the fast idle soloniod valve. It was stuck open creating a huge vacuume leak at warm temperatures.

To diagnose..
1. run the car til warm. (til the fan comes on)
2. Unplug the vacuume line comin out of it and see if there is vacuum pullin into the soloniod.
3. If no - you're done, its a good soloniod
4. If Yes, unplug the 2 pin connector going to the soloniod.
5. If there is still vacuum, you're soloniod is screwed
6. If there is no vacuum, check your ECU and cables for a short to ground.

Hope this helps someone!