My idle speed warm is 1480-1490 rpm, but should be around 750 rpm. The resistance on my Idle Air Control Valve (IAC) is 45 Ohms, also twice as much as specs.

Two Philips screws hold the IAC to the intake manifold. I tried every Philips screwdriver I have, but none will loosen it. I sprayed PBlaster inside the base yesterday, but still can't get it loose. I don't want to use a torch, because the IAC is made of plastic.

Any suggestions on getting the IAC off?

 

Read link below. Part about #2 JIS screwdriver.

https://www.toyotanation.com/forum/1...ead-pitch.html

 

Thanks.

Other than a noisy 1480 rpm idle, the engine is fine. Will I damage the engine if I drive say 100-200 miles before I get the #2 JIS to replace the IAC?

The link really helped. No one recommended a particular brand of screwdriver. Any recommendations?

Also, should I buy only a #2 JIS, or a full set of JIS?

Thanks

 

You will not damage the engine.

As to a set or just one bit. Are you going to be working with addition sizes of screws? Try to get decent quality bits as with all tools, some are better quality then others.

Might also check into getting a drive impact tool. See link below:
Shop around. These tools are very useful for stuck screws. You need to get a proper fitting bit or can damage the screw head if tool loose of fit.

https://www.homedepot.com/p/TEKTON-1...FfcPrQYdI2cGfw

There are some drive bits that have grooves in them to grip the bolt head better.

If nothing works can drill out the heads. Then remove the valve and use vice grips to unscrew the bolt shanks. Thought the link in the previous thread had the bolt size used. Before going this route, get the bolts first to be able to complete the repair all at once.

 

thanks

I was able to remove the screws for the IAC.
The IAC tested normally in terms of resistance between the terminals.
The throttle body is clean.
The vacuum hoses are all connected and I didn't see any cracks.
The engine is still idling around 1480 rpm without check engine light. Any thoughts as to what the cause is?

 

Any other vacuum hose leaks?

Is the throttle plate/arm/pulley fully rotated closed?

Is the throttle dash pot opener button retracting after the engine starts?.

Don't adjust the any screws yet.

 

Thanks.

Here are some updates.

I don't see any vacuum hose leaks or cracks. I used un-lit propane, and didn't see any change in idle speed. I also used a mechanic's stethoscope and didn't hear any hissing.

The throttle plate closes securely; the plate and the cylinder are pretty much clean of tar.

With a vacuum gauge connected directly to the intake manifold, vacuum pressure was normal at 20mm Hg.

My temperature gauge seems normal and the car doesn't overheat. I noticed that my ECT (coolant temperature sensor) is only 3 Ohms cold (normal is 3,000-4,000 Ohms), 6 Ohms hot (normal is 200-400 Ohms). Might that be the source of the high idle problem?

I read that some people replace the throttle bodies; I can't find any new/rebuilt at Auotzone or O'Reilly. If that's a good idea, is there a place that sells them?

I don't understand what you meant when you asked: "Is the throttle dash pot opener button retracting after the engine starts?."
Thanks

 

The throttle body may have a vacuum powered dash pot. This is a vacuum powered device having a pin that moves when engine vacuum is applied.

When the engine is off, the pin extends out of the device to rotate the throttle pulley and plate slightly open. When the engine is running the pin is retracted allowing the pulley to return to the stop.

Did you have the ohm meter at the correct reading multiplication factor?

The throttle plate responds to your foot. Actual idle speed is done by the IAC valve. At idle, the throttle pulley will be the stop in a closed position. The IAC valve will open/close based on what the computer tells it. More air means a higher idle, less a lower idle.

The engines computer will note current engine idle and adjust the IAC valve to obtain what is normal for its programming.

Vacuum leaks can cause issues. The IAC valve also have coolant running through it, thus make sure it does.

A bad ETC can cause issues but make sure the ohm reading is correct.

If the car has A/C there is an idle up function when the A/C compressor is working.

What are you using for service manual info?

See private message.

 

Thanks.

I mis-read the Ohmmeter, so the ECT sensor is nl

No AC or power steering.

I'm using my Haynes book primarily or on-line Toyota specs when I can find them.

Looking at the base of the throttle, there is a screw; shall I try adjusting that?

I sprayed carburetor cleaner down the holes at the inside front of the throttle body to free up the IAC valve, but there was no change in idle speed.

I also adjusted the screw that connects to the throttle, but there was no reduction in idle speed.

Thanks

 

What screw was adjusted?

Note the info in the link sent. Run a few tests.