tb connections

3.0trd · 04-10-2008, 07:24 PM

ok, like I've said before, I got my supra in pieces, and I've never seen one complete so forgive me. On top of the throttle body there are 2, what I believe to be 3/8 hose connectors. one facing the front, and the other facing the drivers rear. they are rusty, so I assume liquid ran through them but I have know idea why liquid would run to the throttle body... I need to know where these things connect to, an up close pic of a 7mge engine bay would also be greatly appreciated, preferably an 89. Help!

cre · 04-11-2008, 12:32 AM

They're for coolant lines. The hoses run from the coolant hardpipe which wraps around the block from the exhaust side then goes up into the TB at the rear. The coolant then exits the TB at the front and the hose runs then to the Idle speed controller. The final length of this route is from the bottom of the ISC to a nipple in the lower side of the bottom intake manifold's flange.

As for why.... it's to ensure that the TB and ISC stay warm enough in high humidity situations where the incoming airflow may permit not only condensation but freezing on critical components... or more simply put, it's there to make sure no ice keeps the throttle plate open when ya want to stop.

It's not uncommon to find it's been bypassed by former owners.

3.0trd · 04-11-2008, 01:23 AM

thanks so much for that! not quite sure what the isc is but I'll search for it. as for where it connects to the lower intake manifold, I can't find a nipple where it would attach to, but I'll look harder. one more thing. There is a rubber circular cover with a one wire connector inside it coming off the main wiring loom that connects to the distributor and coolant temp sensor etc. I put everything I can think of back together and cant see anywhere this could possibly go. is there maybe something on the block this covers that has a 1 wire connector?

cre · 04-11-2008, 03:17 AM

The wire clips on to the oil pressure sender. It's a metal can mounted just in front of the oil filter. The rubber cap covers the can and wire clip.

The ISC is the idle speed controller. It's bolted to the front of the upper intake manifold and has a 4 wire plug and 3/4" air hose running to it.

3.0trd · 04-11-2008, 04:06 AM

yeah, I thought it was the ops unit cover too, but there is no prong to clip the wire onto...

cre · 04-11-2008, 06:10 AM

If it's not the harness plug and oil pressure sender's cap I'm going to need a pic. There's nothing there that looks even remotely like what I'm imagining.

3.0trd · 04-12-2008, 06:52 AM

no, you were right, I though the connection was for a nipple, turns out it just slides on, hehehe. thanks!

04-10-2008, 07:24 PM	#1
3.0trd 3" Exhaust Join Date: Mar 2008 Location: Cali Posts: 76	tb connections ok, like I've said before, I got my supra in pieces, and I've never seen one complete so forgive me. On top of the throttle body there are 2, what I believe to be 3/8 hose connectors. one facing the front, and the other facing the drivers rear. they are rusty, so I assume liquid ran through them but I have know idea why liquid would run to the throttle body... I need to know where these things connect to, an up close pic of a 7mge engine bay would also be greatly appreciated, preferably an 89. Help!

04-11-2008, 03:17 AM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	The wire clips on to the oil pressure sender. It's a metal can mounted just in front of the oil filter. The rubber cap covers the can and wire clip. The ISC is the idle speed controller. It's bolted to the front of the upper intake manifold and has a 4 wire plug and 3/4" air hose running to it. Last edited by cre; 04-11-2008 at 03:40 AM.

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04-11-2008, 12:32 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	They're for coolant lines. The hoses run from the coolant hardpipe which wraps around the block from the exhaust side then goes up into the TB at the rear. The coolant then exits the TB at the front and the hose runs then to the Idle speed controller. The final length of this route is from the bottom of the ISC to a nipple in the lower side of the bottom intake manifold's flange. As for why.... it's to ensure that the TB and ISC stay warm enough in high humidity situations where the incoming airflow may permit not only condensation but freezing on critical components... or more simply put, it's there to make sure no ice keeps the throttle plate open when ya want to stop. It's not uncommon to find it's been bypassed by former owners.

04-11-2008, 01:23 AM	#3
3.0trd 3" Exhaust Join Date: Mar 2008 Location: Cali Posts: 76	thanks so much for that! not quite sure what the isc is but I'll search for it. as for where it connects to the lower intake manifold, I can't find a nipple where it would attach to, but I'll look harder. one more thing. There is a rubber circular cover with a one wire connector inside it coming off the main wiring loom that connects to the distributor and coolant temp sensor etc. I put everything I can think of back together and cant see anywhere this could possibly go. is there maybe something on the block this covers that has a 1 wire connector?

04-11-2008, 04:06 AM	#5
3.0trd 3" Exhaust Join Date: Mar 2008 Location: Cali Posts: 76	yeah, I thought it was the ops unit cover too, but there is no prong to clip the wire onto...

04-11-2008, 06:10 AM	#6
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	If it's not the harness plug and oil pressure sender's cap I'm going to need a pic. There's nothing there that looks even remotely like what I'm imagining.

04-12-2008, 06:52 AM	#7
3.0trd 3" Exhaust Join Date: Mar 2008 Location: Cali Posts: 76	no, you were right, I though the connection was for a nipple, turns out it just slides on, hehehe. thanks!