AC Idle Up Connection Plug

ThunderBolt
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AC Idle Up Connection Plug

Postby ThunderBolt » Tue Oct 08, 2019 9:37 pm

I deleted the PS and AC so I capped all the throttle body ports but I noticed there was a loud vacuum leak from the ac idle up connector... I never capped that because there was not the obvious metal tube sticking out like the PS idle up ports it’s just a open hole. Anyhow when I put my finger over the ac idle up hole my idle jumped up quite a bit. Do I indeed cap this port and adjust the idle down some how?

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jondee86
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Re: AC Idle Up Connection Plug

Postby jondee86 » Tue Oct 08, 2019 11:16 pm

Because a picture is worth a bunch of words, here is one...

Image
viewtopic.php?f=9&t=12011#p79889

Not sure how the A/C idle up valve was connected without a tube, but
that tube lets air into the throttlebody to raise the idle when the A/C
turns ON. Therefore, the idle should drop when you block the port.

If you need to adjust the idle you will find the idle air adjustment screw down
a tube on top of the TB adjacent to the TPS. Turn clockwise to close.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

ThunderBolt
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Posts: 18
Joined: Mon Sep 16, 2019 11:40 am

Re: AC Idle Up Connection Plug

Postby ThunderBolt » Sat Oct 12, 2019 6:22 pm

Update!! So I cleaned the throttle body and plugged all the vacuum ports... looped the coolant lines so there's no coolant to the throttle body. On a cold start my motor revs to 5k!! when I unplug the A/C idle up port revs drop down to 4K. I noticed the idle adjustment screw doesn't change rpms at all. this little Toyota is making me PO'd but not giving up till I get this thing.

ThunderBolt
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Re: AC Idle Up Connection Plug

Postby ThunderBolt » Sat Oct 12, 2019 7:18 pm

Looks like the intake manifold to cylinder gasket is leaking somewhere, I sprayed carb cleaner in the area and the engine revved up. Totally bummed because I used a Toyota metal gasket and torqued all bolts like the service manual said. hopefully this is the cause of the idle problem I have.

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jondee86
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Re: AC Idle Up Connection Plug

Postby jondee86 » Sun Oct 13, 2019 3:44 am

Hmmmm.... if you have no coolant running thru the auxiliary air valve to
heat the wax capsule, the valve will stay wide open all the time. This normally
will supply enough air to raise the idle to around 2200rpm. Don't know why the
A/C idle up port acts the way it does ? However, you must have a decent leak
to get the idle up to 5000rpm.

If you have been mix and matching intakes, one possibility is a smallport intake
manifold bolted to a largeport head. You should be able to locate that leak with
a three foot length of garden hose. Put one end to your ear and probe around
the running engine until you hear a "sucking" sound :)

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

ThunderBolt
Club4AG Regular
Posts: 18
Joined: Mon Sep 16, 2019 11:40 am

Re: AC Idle Up Connection Plug

Postby ThunderBolt » Mon Oct 28, 2019 9:13 pm

I installed a IACV delete plate and resealed the intake manifold and my idle is much lower 1600-1700 but my idle is surging now. When I turn the throttle idle adjustment screw fully in my idle doesn't go lower but when I turn this screw out idle does go higher... think i still have a vacuum leak? I had a code 6 but I adjusted the ignition timing on the distributor and the code is gone, now i don't have any codes showing or check engine light but still chasing this surging idle.

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jondee86
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Re: AC Idle Up Connection Plug

Postby jondee86 » Tue Oct 29, 2019 11:31 pm

You either have a vacuum leak or the throttle plate is not closing 100% (same
thing really). If you press down on the throttle arm as if to close the throttle more,
does the rpm drop a little ? It may be that the throttle stop screw needs adjusting.
Correct adjustment has the throttle arm hitting the throttle stop the smallest fraction
of not much at all, before the throttle plate hits the inside bore of the throttlebody.

If you want to try adjusting the throttle stop screw, make sure you mark its position
first. Back the screw off until the blade is actually resting on the inside of the body
and can't close any further. If that doesn't bring your idle down then the problem is
elsewhere. If it does bring the idle speed down, take up the slack on the adjustment
screw until the throttle arm juuuusssst begins to move and the idle speed starts to
increase. Lock it up there.

Now adjust the TPS as you have changed the TPS settings. Use the idle air screw to
find a compromise setting three bears style... not too low for cold starting and not
to high for hot idle.

Cheers... jondee86
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore, all progress
depends on the unreasonable man.

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