3sgte ISCV issues and repair., iscv repair, boost leaks & fixes Options

[delusionz]

Ok so my ISCV seized so i had to pull it apart to soak in carby cleaner.

Heres how it works, theres 3 wires, pin#2 is positive, pins #1&3 are ground.
Grounding out the left side it closes it, grounding out the right side it opens it.
It basically powers an electro magnet to magnetically motion the door open or shut.




What I found was, it wouldnt free up right away, I had to let it soak for an hour and keep spraying and trying to turn until the grit has dislodged.



Then there was this gasket here, because I didn't have a spare I had to some how manage it back in there while it was warped and expanded. I did this by putting it in the freezer for a little while and then using a few drops of Ados glue to hold it in




Anyhow, I got it fully working now with good cold(1400rpm) start and warm(900) idle, however I noticed a few problems with the design.

1. the standard clamps on the water lines dont hold a good seal and should be replaced.

2. even in the ISCV's fully closed position, by charging the left pin, i could still blow air through it, indicating this is a major boost leak as this is plumbed to the air filter(atmo), and not to a pressurised source like the intercooler, so i propose welding a new breather nipple into the intercooler and securing the hose on both ends with good clamps.

I wanted to invoke some discussion on this as Toyota could have designed it this way if they wanted to but chose not to, and also, what about alternatives such as external stepper motor or 2 wire solenoid units, how would you convert the 3 wire pwm signal...



PS. While on the subject of factory boost leaks, I found the PCV valve can be blown through aswell, I've ditched the factory pcv setup in favour of dash 10 fittings and catch tank. Same goes for the power steering idle up valve which can be ditched, and the port on the back of the manifold capped off.

This post has been edited by delusionz: Jun 16, 2012 - 7:27 AM

[lagos]

2. even in the ISCV's fully closed position, by charging the left pin, i could still blow air through it, indicating this is a major boost leak as this is plumbed to the air filter(atmo), and not to a pressurised source like the intercooler, so i propose welding a new breather nipple into the intercooler and securing the hose on both ends with good clamps.

Do you think this has anything to do with the idle bypass screw on the throttle body?

[Sunny]

Hi,

there is a bimetall spring under the water channel, notice that the throttle body should be hot before you think of a air leak, possible you are currently able to test this too


greetz

This post has been edited by Sunny: Jun 17, 2012 - 10:40 AM

[delusionz]

Lagos sorry I didn't see this post before,

That is NOT and idle bypass screw, atleast for 3sgte. That is throttle return stop! So that the throttle plate doesn't return past closed otherwise it will grind off a new path to make throttle open again. There is a tiny little hole in the throttle plate for vacuum escape when you switch off the motor if thats what you mean by idle bypass

All additional engine air is controlled by the ECU via ISCV and solenoids. the engine should NEVER free breathe outside of ECU control, this takes away from engine braking, idle control, cold start, it makes the ecu think youve always got your foot slightly on the gas and runs in a driving mode when it should be in a closed loop idle mode