Strange Idle

[mjquillici]

I just finished replacing my valve cover gaskets, spark plugs, wires, distributor cap, rotor, and PCV valve. I FINALLY got it all back together. It fired right up and runs like a champ. Before this tune up, once warmed up it would idle down to about 700 rpm. Now, once it's warm, it will only idle down to about 1000 rpm. Then, periodically, the rpms will dip for a second (to about 700), and then go back to 1000 rpm. It does this periodically, maybe every 15 to 45 seconds. I've checked the vacuum hoses, and I don't think I've missed any or mixed any up. Any ideas? I have none.

 

[mjquillici]

Okay, so maybe I have one:

I've been doing some reading, and I'm wondering if my problem is being caused by a clog in the coolant passage on the throttle body. When the idle dips, it almost sounds like a valve is trying to close and the opens again. Should I look onto removing the throttle body and blowing out the coolant line??

 

[mjquillici]

^^ Anyone?

 

[turboSR5]

That symptom can be caused by air in the cooling system. Once the air pocket hits the IACV it causes the idle to fluctuate. I would start by ensuring all the air is out of the system before you pull the TB off.

 

[mjquillici]

That symptom can be caused by air in the cooling system. Once the air pocket hits the IACV it causes the idle to fluctuate. I would start by ensuring all the air is out of the system before you pull the TB off.

What is the IACV?

I tried to bleed the air from the system by removing the radiator cap and letting the engine idle in the driveway for about 15 minutes with the heater control on hot, but coolant just seemed to drip out. Since i pulled the plenum and throttle body, i have probably lost one to two quarts of coolant, but the level in the radiator is full to the top. As the engine runs with the cap off, more just dribbles out. So, I'm pretty sure that there is air in the system, but I have no idea how to get it out.

Help, please?

 

[giro]

Keep the cap on and some extra fluid in the reservoir. Then drive it around a bit. Once it's warm, sometimes going around some corners or up or down something will get that air out.

This happened both times I switched out the thermostat. Even driving up and down a pretty steep hill didn't help (though it was still warming up), and the heater wasn't blowing hot air. But then going around a corner apparently got rid of the air, and all was good.

....but I don't see anything about this in the FSM. Just play with it a little, once it's warmed up. Watch that temp gauge. For me, once the heater started blowing hot air, the air was out of the system.

 

[mjquillici]

Is it possible to separate any of the hoses on the firewall to help work the air out?

 

[541joseph]

Is it possible to separate any of the hoses on the firewall to help work the air out?

I wouldn't get near those. Those are for your heater core. A very big pita if it starts leaking. And you don't want to mess with it if there's nothing wrong.

 

[mjquillici]

I wouldn't get near those. Those are for your heater core. A very big pita if it starts leaking. And you don't want to mess with it if there's nothing wrong.

Just a high idle...1,100 rpm or so.

 

[Ryros92runner]

Here is how the coolant circulates in a 92, from the FSM.

I swapped out the hoses and seals for the oil cooler on my sons 92. After refilling the radiator, I did everything you did and waited for the thermostat to open and watched the coolant exchange in the radiator. I capped it, took it for a spin and it was fine. Maybe you have a problem with your thermostat? Were you having idle issues before pulling the throttle body/plenum?
Beyond that you might try looking on Yotatech, etc. There are a lot of threads on burping 3vze's, from parking on an incline, squeezing the radiator hoses, etc.
We have the top of my sons 3VZE apart, and are going to do the head gasket thing like everybody else. When it is all said and done I am going to put a Prestone flushing tee in the heater hose without a valve (passenger side) and fill the block through the upper radiator hose while holding it vertical. When the coolant runs from the tee I'll cap it, connect the upper radiator hose and hopefully that will be that after warming it up.
Hope this helps,
Jim S

 

[giro]

I swapped out the hoses and seals for the oil cooler on my sons 92.

I've only messed with an oil cooler on a 3000gt, and not the one on my '92 4runner. But doesn't the oil cooler only use oil....using air to cool it rather than antifreeze?

I stared at that very same picture in my '92 FSM. But I couldn't see how to vent it or where coolant went to the heater core (either of them). There are the input/output in the upper right of that picture. But others mentioned the throttle body and that's in about the right location, so I thought that was that.

The FSM does mention opening all 3 vents (I believe that was with replacing the thermostat), but it looked like those were not at the top of the system so they wouldn't help in getting out all the air.

 

[541joseph]

Just a high idle...1,100 rpm or so.

Right I get the problem but I'm saying that messing with the hoses that go through the fire wall could create a very expensive problem.

 

[Ryros92runner]

I've only messed with an oil cooler on a 3000gt, and not the one on my '92 4runner. But doesn't the oil cooler only use oil....using air to cool it rather than antifreeze?

The inner core is filled with oil. It has fins that are cooled by the coolant circulating between the core and outer jacket. The inlet hose comes from the side of the block, the outlet hose goes to the small inlet on the water pump. The location of the oil cooler on the 4WD is the location of the oil filter on the 2WD 3VZE. Basically on the drivers side, to the right of the motor mount.

I stared at that very same picture in my '92 FSM. But I couldn't see how to vent it or where coolant went to the heater core (either of them). There are the input/output in the upper right of that picture. But others mentioned the throttle body and that's in about the right location, so I thought that was that.

The heater core outlet hose goes from the firewall on the passenger side to the Water Bypass pipe #1 that runs under the intake manifold. The inlet hose comes up from the Water Bypass Outlet, does a 180, goes through the valve and enters the firewall on the drivers side. There are no vents like you say, though you might try venting through a TB hose.

The FSM does mention opening all 3 vents (I believe that was with replacing the thermostat), but it looked like those were not at the top of the system so they wouldn't help in getting out all the air.

You're right, unless you vent it at the top of the system you won't get all of the air out. It might help to pull a throttle body hose as you fill and beyond that the radiator cap will take care of the rest.