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What corrections could cause a high idle?

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1997 subaru wrx sti

Haltech elite 1000

The car idles around 2300 rpm, and the target idle is around 900-1100. There are no vacuum/boost leaks. Base timing is set correctly, crank and ecu read the same value. the ignition advance is not following the base table. all sensors read correctly. with the tb set screw backed out rpm doesn't change.

30deg advance at 2300rpm

map is -9 psi at 2300rpm

Lambda is rich, 0.75-0.78

The things I'm not sure of is if my injector dead timetable is perfectly accurate, I've tried a few different tables but none seem to have much effect on the idle speed also not 100% on if my coil dwell time is accurate since I'm working off a base map.

When I change values in the ignition base map the ignition advance does not change.

What corrections at idle could cause such a dramatic increase in rpm?

I've messed around with zero demand, bringing the value down around 2300rpm. lowering the value to 9deg of advance brings the idle down to 1700 rpm, going any lower with the value does nothing for the idle.

The engine needs significant air to hold that sort of idle speed - there IS somewhere it's getting into the engine, whether it's past the throttle butterfly which isn't actually fully closing - have you tried physically blocking the intake with a sheet of cardboard, or similar, to eliminate that, as some may not seal totally? - via missed or split vacuum lines, a leak through gaskets/flanges, a faulty brake booster/servo, or something else.

A common check for leaks is to spray a little engine start, or brake cleaner, around the engine as any being drawn into the engine will raise the idle speed.

Only when it's passed, and repassed, air leak tests should you start looking elsewhere.

As Gord said, there has to be air entering the inlet plenum for that engine speed to be maintained.

Is there a small amount of slack on the throttle cable when the throttle is closed? I have sen the cables adjusted so that they are holding a tension when off the pedal, this then cracks the throttle open enough that idle speed is not controlled.

The EJ manifolds have a number of ports off of them, check that each hose is in place and not damaged, and that any of the ports that are supposed to be blocked have their stoppers in place.

Have you backed off the throttle stop screw to reduce idle air?

Have you confirmed the idle air motor isn’t stuck open?

The iac valve was seized up just enough so that it could be moved by hand but the actuator could not move it. I freed it up and it works perfectly now. Thanks guys!

Great, very common with that particular valve. You're welcome.

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