My 01 4cyl has an erratic idle. When I first turn it on in the morning it seems to idle fine until it warms up. When I drive it on the highway, it will drive fine until I attempt to speed up. It will be a gradual increase in acceleration before it finally darts forward like there's no problem.
I searched the web and found multiple possibilities. So, I changed the idle air control, MAP sensor and throttle position sensor. I had the battery disconnected while I changed those parts. Sadly, the parts I removed said, "Made in USA" and I replaced them with parts that said, "Made in China." Anyway, the car idled very well the first day then went back to the erratic the next morning. Actually, it's worse! Maybe it's these Chinese parts, I don't know, but it sounds like it's going to stall eventually.
I haven't been able to check for ODB codes because every place I stop by gives me an excuse as to why they can't take a minute to plug their machine to it. Whatever.
The car has 202K miles and drives very well despite the erratic idle. I'm open to suggestions on what the problem could be.

 

Code readers are cheap. Get one and educate yourself. YouTube has plenty of diagnostic videos.

 

Gee thanks, that was a lot of help.

 

It's good advice. You're obviously too clueless to heed it.

 

A big middle fin...whatever. you're an ***. I've been working on cars for over 35 years. I have a code reader, but it doesn't show codes for this car. It didn't show codes for my last Camry either. But, it works because it showed codes for other vehicles I used it one. I was just asking if someone found a solution to this evasive problem that 's apparently common on Camry's. The moderators want us to be nice. So I'll refrain from what I truly want to say to your rude ***. Just go away if you're not going to be helpful.

 

You didn't mention that you had a code reader. Hey, just keep throwing parts at it. You are truly an idiot.

 

You are an *******

 

Looks like someone is "triggered"!!! 🤣🤣🤣🤣🤣🤣

 

Please stop the back and forth! The point of this website is to solve Camry problems.

Is the idle erratic only after warm up? IAC valve controls idle speed.

Does the engine also bog down or fail to respond when giving it throttle? Before/after warm up or all the time.

Did the problem start up as in the engine ran OK before this?

In addition to the ODBII codes Toyota has their own. One needs a reader that the Toyota software. Not sure if it makes a difference in this case.

Not everything is monitored directly by the ECU which could result in a code.

A lot of auto parts are made in China now. Some are good and some are not so good.

The MAP sensor seldom fails. The TPS is a good start. The IAC can get dirty and need cleaning.

Does your scanner have real time output for coolant temp, A/F sensor readings, etc?

 

Maybe they got it repaired.