i started to notice that after it warms up (letting it idle for 5-10 more mins after warm up) or after driving it under normal conditions, it'll rev by itself to about 1500rpms-1800rpms for about 5-10 seconds then it'll go back down to normal idle? sometimes it'll do it right after another. does anybody know why it does this? i have cleaned the maf, tps, throttle body but not iac. i do not have the defrost or a/c on when it does this as well. any input is appreciated. thanks in advance.

 

could be the coolant temp sensor, that sends the signal to the ECM!! they wear out and cause a high idle issue or maybe some times your sporadic issue!!!

 

When you clean the TB and not the IAC, you're really just making the IAC even dirtier, so I would start there. If it is the coolant temp sensor, they're cheap (<$20) and easy to replace too.

 

hey brian2sun, if i had to change the coolant temp sensor, where is this located and what does it look like? thanks bro.

 

The sensor itself looks like this:


You just remove the plastic timing belt cover and it's behind there right on top of the engine. You'll probably have to disconnect a metal fuel line on one side and slide it out of the way the get to the temp sensor. There's a special lipped washer between the fuel line and the rail that is easy to lose so be aware and don't let it fall out. Take the old sensor out with a ratchet and socket and wrap a little teflon tape on the threads of the new one before you put it in.

 

I try to point out the cheap stuff that wears and if it was not the problem it will not be for a very long time!

I agree as well on the IAC but really would suggest doing both Would be nice to get out od this for like $25-$30 and have no more issues!!

 

Awesome thanks guys. Will do it by this weekend and keep ya updated.

 

ahtub I had the exact same problem with my 97 Tacoma 3.4 My problem was the IAC Valve. My Tacoma had 223K when I bought it and the problem started out as yours is where it would just idle up for 10 seconds on warm-up. It will get worse and you will begin to notice that when its idled up and you shut off the engine you cant start it. Clean the IAC out ASAP it left me stranded. Here is a good write up that I used and also VERY important when putting the Valve back together DO NOT use to much sealant if it leaks over onto the magnet it will cause the valve to stick inside the valve.

https://www.yotatech.com/forums/f123...ac-pics-92286/

 

thanks guys. i cleaned the iac and tb today and it runs really smooth and quiet now. no more bad idle too