Smallport - vacum leak.

[Smitty]

Car - ADM AE86 with smallport 4AGE

Problem - Vacum leak (whistling from intake side of engine) on acceleration, launch and low RPM load conditions. Also, used to cold start idle at 2500RPM, then never below 1000 when warm.

Occurs/started when - I got the car on the road about 6 months ago. I have just put up with it but it feels like its lagging and the whistle is pretty annoying. Plus, I'd like to have everything working correctly if I can.

Use - Daily, weekend cruising.

The intake manifold has been cut and shut at the ends. The welding is quite good and not porous. As a temparary compensation, I removed the IAC housing off the bottom of the throttle body, and made a new gasket with smaller passages. It starts, warms, then idles properly now just with a loud vacum leak. My main question is where do the pipes pointing forward under the throttle body (while in RWD format) go in a factory corolla sx? I am using the two coolant lines underneath, the top two pipes going forward, I have joined together and the bottom two are plugged.

Let me know what you think guys, cheers.

[Nikkojoe]

The two that point forward go to power steering and to block them you DO NOT loop them as it just creates a bypass and keeps the idle high. You need to cap them individually. And you are talking about the top two on the IAC housing right?

The bottom ones (one that points sideways) goes to a/c idle up vsv. The other (if there, commonly found on bigports) is a small vac line for a throttle return dampner.

[Schnickles]

On the last manifold i cut and shut there was a small passage in the plenum from the breather pipe on the side which then goes internally to the throttle body and comes out in front of the butterfly not sure if all are like this but when we cut and shut it no longer lined up so we needed to block the original breather on the manifold and also remove the throttle body and block it behind that too this fixed the problem then you can tap the breather into the filter pipe before the throttle body or just run it into a catch can, Not sure if this is your problem but mite be worth a look