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Discussion Starter #1
Hi all,

My 2002 Toyota Highlander has been my workhorse for 8+ years and now her and I have 226k miles. About 6 months ago I noticed when I would start the engine, it would occasionally (once a week) idle very low. Around 200-300 rpm. Eventually it became more and more frequent and one day it started and stalled out right away.

I did research online and discovered the easiest possible solution might be the MAF sensor. I took it out and it was rather dirty so I cleaned it with the appropriate MAF cleaner and it initially seemed to help the idle but alas, the problem returned.

Yesterday I took the air intake tubes off the Throttle Body and cleaned the butterfly valves and surrounding area with Throttle Body cleaner and a micro fiber. It was rather dirty so I thought that would fix it but now the car won’t start. It completely dies/stalls out and won’t stay on unless I have my foot on the pedal to keep the rpm high.

is it the throttle cable? Or possibly something else?
Thank you for any help you have to offer!
 

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99 RX300, 02 HL V6
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It's good that you have cleaned the Throttle Body...now, address what I believe is the real culprit...the Idle Air Control Valve. In my opinion, at some point in their life they become so coked up that they are impossible to clean, but you can try it...but the easiest solution is to simply buy a new one and throw the old one away. I did this on both my 02 Highlander V6 and my Lexus RX300. I bought the Standard Motor IAC from RockAuto and did the job about 3-4 years ago. They run great now. Let us know if you do this job and what the results are. Good luck.
 

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Discussion Starter #3
It's good that you have cleaned the Throttle Body...now, address what I believe is the real culprit...the Idle Air Control Valve. In my opinion, at some point in their life they become so coked up that they are impossible to clean, but you can try it...but the easiest solution is to simply buy a new one and throw the old one away. I did this on both my 02 Highlander V6 and my Lexus RX300. I bought the Standard Motor IAC from RockAuto and did the job about 3-4 years ago. They run great now. Let us know if you do this job and what the results are. Good luck.
Ricco, thank you for the quick response.

I will give this a go today and let you know what comes of it!
 

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Discussion Starter #4
It's good that you have cleaned the Throttle Body...now, address what I believe is the real culprit...the Idle Air Control Valve. In my opinion, at some point in their life they become so coked up that they are impossible to clean, but you can try it...but the easiest solution is to simply buy a new one and throw the old one away. I did this on both my 02 Highlander V6 and my Lexus RX300. I bought the Standard Motor IAC from RockAuto and did the job about 3-4 years ago. They run great now. Let us know if you do this job and what the results are. Good luck.
Quick update, I was removing the sensor cables to the throttle body, more specifically the one I believe lead to the Idle Air Control Valve and the locking mechanism was broken. Is it possible it wasn’t reading properly due to this? Also is this a difficult fix? I’m struggling to find a part number for this.
Thank you!
 

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99 RX300, 02 HL V6
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As long as the connectors seem to mate properly, it was probably "reading properly". You can clean the connectors and test continuity. You can probably secure the part with a small cable tie. But a new part would of course be nice. If that part had not been connected, I would bet it would have thrown a CEL, but don't know. Heck, you could probably use a little JB Kwik on a strategic place. Don't know the P/N, sorry, or if it's even available as a discrete part, might be part of a wiring harness assembly, $$$. Do you plan to replace the IACV ? If you do, it's also a good time to do a coolant drain and fill. And replace the thermostat...the list could go on and on :)
 

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A car not idling properly after tb cleaning is a common issue heard all over the internet. The build up around the throttle body butterfly valve let's it open and close so much and the computer compensates for that. When you cleanup that buildup it opens/closes different than before, the computer gets confused and needs to relearn. Had to do that on my 2006 after a tb job so I started it and let it idle for a while. Yours might have a different process so look that up

About the connector tab breaking off, dont worry. After many miles of being near the engine heat cycles they become fragile and break easily. So replace that iac first and then let car idle. You can use locking pliers on hoses you take off the iac to quickly swap it without losing any coolant and not making a mess. Here are my front 3 coil harnesses I had to secure with zip ties:


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I cleaned the throttle body on my old sable a few years ago and that ruined the iac. Must have shorted it out or something, but the car wouldn't idle after that until it was warmed up.
 

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It's good that you have cleaned the Throttle Body...now, address what I believe is the real culprit...the Idle Air Control Valve. In my opinion, at some point in their life they become so coked up that they are impossible to clean, but you can try it...but the easiest solution is to simply buy a new one and throw the old one away. I did this on both my 02 Highlander V6 and my Lexus RX300. I bought the Standard Motor IAC from RockAuto and did the job about 3-4 years ago. They run great now. Let us know if you do this job and what the results are. Good luck.
do you have a pic? maybe the location of the part?
 

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It should be right on the throttle body, as it's a valve that lets some air bypass the throttle to adjust idle speed.
 
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