Throttle Body Cleaning - Any Tips?

[nissanh]

I noticed the RPM at idle is about 1000 and when I check the coolant temperatures going into Idle Air Control (IAC) valve is 73 Celsius (163 F) on small diameter coolant by-pass hose and 43 Celsius (110 F) on the wider hose connected to the metal tube in front of the timing belt cover.

Isn't the RPM should be around 600?

When I bought the truck I found some carbonate deposits and I suspect this might have clogged the IAC. I am ready to pull it apart and give a good cleaning, especially the coolant lines. No codes at present.

Can I apply pressurized air through the coolant lines to flush out any residues?

Anything else I should do while I am there?

Thanks.

 

[RyanStl]

I was going to say get a lot of toothbrushes when I read the title of your thread, but then reading the thread it sounds like you know 100 times more than me.

 

[Mauser]

When I pulled my throttle body to clean it I looked inside the intake manifold and it was nasty in there too. I ended up pulling the manifold and cleaning it out.

 

[512LX]

600 RPM at Idle? mine is around 1200 and when the ac compressor kicks in it jumps up to about 1400. I think i have something major going on if its suppose to be at 600rpm.

 

[nissanh]

WAIT!
My V6 5vzfe 4runner engine idles at 700. It been a V6, the idle rpm seems right, 4 cylinders should idle about 750. Based on this I though a V8 should be around 650 or so. I found thread about 80 series idling at 650.

I have the current idle on my cruiser at 1050 and with AC, yes, it gets to about 1100.

After looking at the throttle body in the cruiser, I do not find air by-pass like I see in my 5vzfe 4runner throttle body, so I am not sure how the idle air control is done on the cruiser and the point of having coolant in the throttle body.

 

[Spike555]

Mine idles around 600-700rpm hot with no load.

 

[nissanh]

Could you please do me a favor. If you have an IR thermometer, could you check the temperature of the two coolant hoses coming in and going out of the idle air control valve when the engine is hot and idling

 

[512LX]

Ill ask some friends but I dont have an IR thermometer

 

[dace voit]

Warm idle in neutral=650. Warm idle in drive=600. That's with the a/c off. The a/c will, of course, raise the idle. My 100 idles with these numbers, as did my 80.

 

[Eicca]

IIRC Starting in 1998 the UZ V8s did not use an idle air control valve. The idle speed is controlled via the electronic throttle plate and the ECU does all the work.

A dirty throttle body can cause a rough- or no-idle condition.

The coolant hoses on the throttle body are there to prevent ice buildup in cold climates. If you live somewhere that isn’t cold you can bypass them without issues. The jury is out on whether or not this gives you any perceivable increase in power.

 

[nissanh]

^^^ Great information. Thank you!

Yes, when I looked at the wires, there are total of two wire plugs and one has 4 wires which goes to TPS and other has 4 going into the motor, so I wondered how the idle air is controlled. My 4runner with 5vzfe V6 engine has 3 wires coming into the throttle body which is purely for idle air control.

OK, I'll go ahead and clean the throttle body once again to see what will happen to the RPM.