Gen 1 3sg high idle, need diagram

**Rhyno** · 14-07-2012, 02:22 PM

Hi all,

Bypassed the water circuit today through the throttle body, and when I finished my engine is now idleing at 1600rpm.

Thinking I may have an intake leak I had a good look aroind, then started spraying around with some throttle body cleaner to find the leak. Couldn't find any.

So I wound in the idle adjustment screw until it was shut, only dropped the revs by 100 down to 1500rpm.

Then I sprayed some up the intake, and the revs instantly dropped. Their is three ports inside the throttle body before the butterfly, the top being the supply for the pcvv and the other 2 I couldn't identify.

So I partially blocked the bottom port and my revs dropped down...

Can anyone link me to a diagram or point me in the right direction? My Chilton Celica manual and toyodiy.com are not proving to be off any use.

Kind regards,

Ryan

**jonathan yee** · 14-07-2012, 04:34 PM

Hmm, im not sure you can remove the water feed from the tb iscv as it relies on this for cold start idle up. Ie when the water temp is up it will reduce the idle. Now you have disconnected the water feed the iscv will always be open.

If you really want to not have water going to the throttle body you will need to adapt an elec iscv.

**Cuts** · 14-07-2012, 08:50 PM

**thechuckster** · 14-07-2012, 10:14 PM

i had the same problem on an ST162 I helped repair - the idle control valve needs the hot water supply.

**4th surf** · 14-07-2012, 10:17 PM

I'd go with the pic that Cuts has posted. Unless you're using Firefox for a browser from my experience all other browsers don't display the pics. When you do get the pics however unless you know what you're looking for it is hard to find the map for the vacuum hoses. Also do a DTC (code) check as most 'yotas will idle up if there is one present. While I think about it follow the hoses to the power steer "idle up" and make sure that nothing has fallen/broken off there. The pressure sensor will either be on the rack or the pump. Yet for some reason I think that you may have created this problem by bypassing the "cold start" which in this case is an air bleed that makes them "idle up". This all said it's probably going to be something small and stupid that takes ages to find and damn near drives you nuts in the process

**jonathan yee** · 14-07-2012, 10:39 PM

the gen1 iscv is "wax pellet"? type. it directly needs the water to mechanically control the iscv, hence when people don't bleed the coolant system properly or get air locks in the iscv it doesn't get the heated water required to close the ISCV.

**thechuckster** · 14-07-2012, 10:49 PM

yes, and once the small hoses feeding the ISCV get clogged with rust/gunk (usually from a poorly repaired BHG, fancy that), you get epic idle speeds.

**Rhyno** · 23-07-2016, 03:39 PM

Just wanted to thank you all for your help on this one, car ended up sitting for a while due to buying a house, but recently got it back on the road (with a gt3071 :-) and ended up reconnecting the water lines back up the intake and idle was back to normal

Thanks again, and sorry for taking FOREVER to reply

Kind regards,

Ryan