RacerX2015

I'm working on a 1991 Toyota pickup, 3L V-6, automatic. About 160K miles on it. Needed to do some much needed maintenance, like fix the leaking power steering pump, replace a bad TPS and change the leaking valve cover gaskets. So I removed the upper plenum and throttle body assembly. Went ahead and separated the TB from the intake to clean it. My question is what is this (see pics) and do I need to service it? Can not find anything in any manual that tell me what it is and how to service if required. So if anybody knows what it is and how to service it, It would be greatly appreciated.

MudHippy

It's called the Idle Speed Control Valve(ISCV). It's technically "maintenance-free". There should be no need to service it. In other words, if it ain't broke...don't fix it. However if it is broke...there are things you can do to fix it. How you know if it's working or not is somewhat complicated. But summed up, when you start the engine after a long cold soak(and/or when the coolant is below operating temps) the idle speed should be ~700 RPM higher than when the engine is fully warmed up. So you want to see ~1500 RPM idle speed when the engine is cold. Then after it's warmed up, it should drop to 800 ± 50 RPM idle speed.

snobdds

The entire unit is the throttle body...which houses the IACV (idle air control valve) and the TPS. IACV is the term Toyota uses, that may help you in your search...

RacerX2015

If you look for a idle air control valve for this truck it doesn't come up anywhere! I've looked and looked!! LOL LOL But before I started this project I did have issues with the idle when the truck was cold. That's when I started checking stuff and found that the TPS was bad. I was also told that when I replaced the TPS to clean the TB real good and the idle control valve/idle speed control valve. So how does one go about cleaning and checking this??

snobdds

Your not going to see a seperate IACV for the 3.0 as it's part of the throttle body...

As long as it's hooked up correctly and nothing restricting the air or coolant...it should work.

RacerX2015

So do I take it apart and clean it or not??? That is the question?? LOL LOL

snobdds

I wouldn't. There is a bi metal spring in there that, once messed with, is never really the same.

Just make sure it's clean...

RacerX2015

How do I do that?? Should I just squirt some TB cleaner in there and blow it out the best I can?

snobdds

Yep. They usually only have problems with crap in the coolant blocking flow to the spring.

MudHippy

Well...call it what you will. We're both right about that. But you can make up your own mind about what to do with it.

Here's some good reading: https://www.yotatech.com/forums/f116.../#post52319105