AW11 20-Valve ST Swap High Idle Problem

[hachidustin]

Okay, so me and a buddy just swapped a ST 20 Valve into his AW11 with a BT ECU and MAP sensor. The car starts up fine, but it idles anywhere between 2900 and 3800 even once it warms up. I disconnected the TPS while it was running and it started idling a little rough. So I'm guessing that's working. Then I unhooked the MAP sensor while it was running and it made the idle shoot up to like 7k. The o2 sensor is not hooked up and we've kind of hit a wall on what to do.

Any suggestions would be great and useful.

[yoshimitsuspeed]

First off hook up an o2 sensor. It's not your entire problem but when you know something is wrong then it's the best place to start.

As for the idle. Too much air is getting in somewhere.
Look for intake leaks, disconnected vacuum lines etc.
Make sure the ISC is hooked up and functioning properly.
Make sure the throttle plates are closing all the way.

[hachidustin]

It turned out to be a vacuum leak. Two of the 4 throttle bodies were not opening due to a vacuum line not attached to a vacuum actuated diaphragm thing that was below and between the 2nd and 3rd throttle bodies.

[yoshimitsuspeed]

It turned out to be a vacuum leak. Two of the 4 throttle bodies were not opening due to a vacuum line not attached to a vacuum actuated diaphragm thing that was below and between the 2nd and 3rd throttle bodies.

Dangit, can't believe I didn't think about that.
Let's just say it's not an uncommon mistake.
It wasn't just a vaccum leak. That dashpot retracts slowly to keep the engine from stalling when you let off the gas. If it doesn't see vacuum it will hold the throttle plates open.
Glad you found the problem.

[hachidustin]

Haha you were pretty damn close though. Thanks for the help though.