H23 Intake Idle Surging

[GTRON]

Hey Guys,

Me and a friend out in a H23 Plenum and runners in my car yesterday (Also Manual Swap if that would have anything to do with it). To our dismay when we started it, it has this atrocious idle surge from 1k to 3k. After fiddling around with vacuum hoses we found that if we took the vacuum hose to the MAP Sensor it would stop surging. We've checked the idle valves and such, even swapped them out, but nothing has stopped the surging (besides taking off the MAP Sensor vacuum hose).

Help would really be appreciated, as I need to drive this car home!

[rustyaccord]

I'm having a similar issue. I have tried everything short of tearing out the intake manifold and replacing all the gaskets and vacuum lines.

[excalibur02]

spray some brake cleaner around the intake manifold, If it stops idling then you might have an air leak.

Have you tried to adjust the fast idle valve?

[GTRON]

I'm having a similar issue. I have tried everything short of tearing out the intake manifold and replacing all the gaskets and vacuum lines.

Does it make a really loud hissing/air noise?

Mine was the idle valve on the throttle body.

If it's making a loud hissing noise, and surging really bad, try sticking your finger on the bottom of the two holes inside the throttle body while the engine is on. (If that makes sense) The two small air holes right before the throttle butterfly valve (when you take off your filter/intake).

If that stops your surging problem, that's what's wrong.

Hope that makes sense

[Raf99]

Yep and check at the other end of that vacuum line...

[rustyaccord]

It doesn't make any abnormal noises, it goes back and forth between idling really high (1000 - 2000) and fluctuating between 1200 - 2000. I emptied a whole can of carb cleaner all around the intake, vacuum black box, brake booster but couldn't find any vacuum leaks. It's probably just the throttle body needs cleaned and adjusted.