ITB's diaphram??

[touge_ae101]

just wondering what the diaphram on the underside of the throttle bodies from a 20V actually does? only mention i can find of it is here viewtopic.php?t=76971&highlight=iscv++valve

is this correct that it is just a cushion to stop the throttles closing too quickly? if so has anyone removed this?

its for a racecar so nasty backfires are awesome, not a hindrence. currently it is stopping the throttles from sitting on the stops properly, causing a nasty rev up on startup and potentially damaging the bearings etc. if we can get rid of it we will but if it is neccessary then more adjustment is needed.

Cheers
Rhys

[fxgt race]

In The bin thats where my one went.

[QikStarlie]

yeh can bin it as above, its there to stop throttles slaming shut as you say. which can cause engine to stall in some cases..

on my old setup i modded it to work as a cold start idle up. new setup ive removed it as it doesnt fit..

[touge_ae101]

cheers guys. my thoughts exactly.

[RedMist]

mmmmm.... antilag idle up. Anyone have a shot of it?

[jondee86]

just wondering what the diaphram on the underside of the
throttle bodies from a 20V actually does?

It is actually the Throttle Opener, and Autoshop101 describes its
function thus...

Non-ECU Controlled Throttle Opener
Starting with 1990 3S-FE and 5S-FE engines, a simple throttle
opener diaphragm was added to the throttle body. The throttle
opener diaphragm is spring loaded in the extended position,
holding the throttle valve open slightly when vacuum is not applied
to the diaphragm. When the engine is started, manifold vacuum
from the TO port retracts the throttle opener for normal curb idle.

The intent of the throttle opener system is to keep the throttle
valve slightly open after the engine is turned off.

Keeping the throttle slightly open is set down in the Black Top
service manual as raising the idle to around 2500 rpm if you pull
the vacuum hose from the diaphragm. AFAIK the idea is to provide
a bit of extra air for starting. But as the throttle opener is retracted
while the engine is running, it will not affect the throttles snapping
closed. That would be the job of a dashpot is one was fitted.

Cheers... jondee86