Vacuum switch to increase engine idle for A/C load; desi hack or standard way?

[stranger729]

A vacuum switch (race-valve in desi talk) was installed today. (4EFE engine in EE80)

Now there is hose/pipe connecting one port of switch to engine's air intake (apparently, after the throttle body assmbly). The other port of vacuum switch is left open.

From what I understand, when the compressor turns on, this switch lets extra (unfiltered) air flow from the atmosphere into engine's air intake.

1. Is this a Toyota design or a successful desi hack/jugaar?
2. Should we let unfiltered air get in like that? Can an air-filter be added to this setup?

[Xulfiqar]

its correct toyota design but the atmosphere port is never left open, in original form it shares a port from the airfilter box or a port on the throttle housing depending on the version of 4EFE you have.

In simple words - any air that has to enter the engine will be filtered first.

how did your mechanic connect it btw - the original is a valve with a screw on top to adjust the rpm and is triggerd by the ISC pin on the ECU which sends a negative 12V to make it work.

Did your mechanic connect it to the ECU or just spliced into the compressor wiring?

[stranger729]

From the images on this page, it seems that I have 2nd generation of 4EFE (with its peculiar shaped air intake).

The mechanic spliced it into the compressor wiring. The A/C system's wiring was untouched when the 4EFE was swapped into this EE80 (86 Corolla) few months back.

Now, my immediate concern is to ensure filtered air goes through this switch. Apparently, it should be a hose/pipe from the switch's port to one of the places you mentioned. I will try posting photos of the airbox and throttle body.

[capsat]

@syncview @ser_gtr TOOOTKAz

[SER_GTR]

This Kinda Valve Comes In 4AFE 5AFE To Adjust A/C Load

Forget Abt ISC PIN...Its Usually Used Or Connected WIth A/C switch Directly Here....

[stranger729]

Thank you @capsat for pulling in the experts!

Thank you @ser_gtr for the clarification.

@xulfiqar
Took the car early morning to the engine-mechanic. With experienced hands, he felt an unused port on underside of the throttle housing. Then he connected a pipe from the switch's open port to unused port on throttle body and... problem solved! And yes, this valve has a screw on top to adjust the rpm. Thank you for your insightful and very helpful answers.

[Xulfiqar]

Thank you @capsat for pulling in the experts!

Thank you @SER_GTR for the clarification.

@Xulfiqar
Took the car early morning to the engine-mechanic. With experienced hands, he felt an unused port on underside of the throttle housing. Then he connected a pipe from the switch's open port to unused port on throttle body and... problem solved! And yes, this valve has a screw on top to adjust the rpm. Thank you for your insightful and very helpful answers.

That unused port connects to a "tree" which also leads to the power steering high pressure switch, it also raises rpm when it senses that the steering vane pump is working too hard.

[stranger729]

@xulfiqar This is new for me!

Where is this power steering high pressure switch located on a 4EFE?

And to increase engine rpm, is it wired to turn on the vacuum switch for A/C ?

[Xulfiqar]

@Xulfiqar This is new for me!

Where is this power steering high pressure switch located on a 4EFE?

And to increase engine rpm, is it wired to turn on the vacuum switch for A/C ?

its on the pump itself, its a mechanical valve which opens up under a certain pressure.

[stranger729]

Hello,

It has been a while.

In the meantime, I visually inspected the pump few times; no trace of valve on it. I rev up engine slightly to easily move the steering wheel; its now a habit.

[Xulfiqar]

Hello,

It has been a while.

In the meantime, I visually inspected the pump few times; no trace of valve on it. I rev up engine slightly to easily move the steering wheel; its now a habit.

this valve also replaces the banjo fitting on the high pressure pipe, it has two vacuum tube fittings on it.

[lahori]

My car drops RPM when AC switched on, the mechanic says that vacuum is not building which increase the RPMs on AC load. Car is Lancer having 4G13.

[Xulfiqar]

My car drops RPM when AC switched on, the mechanic says that vacuum is not building which increase the RPMs on AC load. Car is Lancer having 4G13.

carburettor 4G13?

[lahori]

no its fuel injection 2006 model