420A 2gNT Idle at 4k rpm

[Chris072901]

I have a 2g eclipse 420a non turbo and i started my car after a rebuild and it automatically jumped to 4k rpm and sat there for about 15-20 seconds then shut off, i believe i have all of my vacuum lines connected besides the vacuum reservoir for the cruise control i was wondering if that is the cause of the problem or if its the idle air control valve, any help is appreciated thanks!

 

[1990TSIAWDTALON]

The reservoir is usually tee'd into a vacuum source that goes to the acuator, IIRC. If that isn't being used, did you plug the place where it normally would have a vacuum line from the reservoir? If not then you probably have a huge vacuum leak. Put a vacuum gauge on the motor and see how good of vacuum it has. It should be 18-20+ in/hg. If it is low, then you more than likely have a leak. Spraying water around different areas with a spray bottle is sometimes helpful in tracking down the general area.
I am puzzled why it just shut off though.

 

[BLACK'98DSM]

What throttle body are you running? When I first put my 60mm tb on, I had a problem where the cable would get wedged and leave the throttle 1/3 of the way open. It idled at 4k rpm.

Anytime you delete part of the vacuum system, you need to cap it off with a vacuum nipple (or vacuum cap).

If you still think it's the idle air control valve, try taking it out and turning the tip counterclockwise a little bit. Turning it clockwise makes the car idle higher, and counterclockwise makes it idle lower. If you have an upgraded tb, then you may have to adjust it as far out as it goes. That's what I had to do.

Like @1990TSIAWDTALON said, spraying water on the leak should make the engine idle down a little bit or stumble. So that's a pretty good idea in this case, as opposed to using starting fluid which would make it idle up (not good here).

Try holding the throttle wide open while starting the car. This puts it in flood clear mode. The ecu might have gotten confused and richened up a bit which fouled the plugs.