Idle Speed RPM wavers

[JV3421]

Hi TN Avalon 1st Generation Onwers/Users,

I am a 1997 Avalon XLS 116650 miles user.

I have a problem on my 97 Avalon XLS on Idle speed which is very infrequent.
My car is running fine most of the times, but at times, the idle speed will be wavering.
If I slow down my car, the engine will show signs like it is going to stop, but will come up to regular running speed & again show signs like it is going to stall.
This will be continuing & my RPM meter hand on dashboard will be wavering. down up down up down up down up... & exhaust will not be smooth.
At this condition, if I have my engine stopped for 45-60 minutes and restart it will be just fine. I am able to drive normally.
When the problem was occurring I had my hood opened and checked.
Under the Idle Air Control (IAC) valve, some thing is going up and down.

Anyone able to figure out the problem area from the above explanation?
Anyone experienced the same problem and fixed it?
Please help me.

Thinking this problem could be a fuel line problem, I used twice the fuel line clean gas mix from Chevron, also. No help. Idle speed problem persists. Problem disappears only after a 45 min stop of engine whenever this problem occurs.

Various posts are available on this forum, but I do not know which one is similar to mine.
It would be very helpful if people experienced the same problem can tell me the forum post they used to fix this problem. Thanks in advance, a much.

[TrailDust]

Just a suggestion, but for the problem you're describing I'd also consider the secondary ignition system. I'd start troubleshooting with the most obvious/common fuel issues first, then check the same with the electrical. If neither resolves the issue, then check the less common ones. Hopefully, someone who has resolved this same issue will provide you more precise advice. Best of luck!

[96paseo]

Try cleaning your MAF with some cleaner. Your local auto parts store should have one thats specific for cleaning sensors.

[artbuc]

Originally Posted by JV3421

Hi TN Avalon 1st Generation Onwers/Users,

I am a 1997 Avalon XLS 116650 miles user.

I have a problem on my 97 Avalon XLS on Idle speed which is very infrequent.
My car is running fine most of the times, but at times, the idle speed will be wavering.
If I slow down my car, the engine will show signs like it is going to stop, but will come up to regular running speed & again show signs like it is going to stall.
This will be continuing & my RPM meter hand on dashboard will be wavering. down up down up down up down up... & exhaust will not be smooth.
At this condition, if I have my engine stopped for 45-60 minutes and restart it will be just fine. I am able to drive normally.
When the problem was occurring I had my hood opened and checked.
Under the Idle Air Control (IAC) valve, some thing is going up and down.

Anyone able to figure out the problem area from the above explanation?
Anyone experienced the same problem and fixed it?
Please help me.

Thinking this problem could be a fuel line problem, I used twice the fuel line clean gas mix from Chevron, also. No help. Idle speed problem persists. Problem disappears only after a 45 min stop of engine whenever this problem occurs.

Various posts are available on this forum, but I do not know which one is similar to mine.
It would be very helpful if people experienced the same problem can tell me the forum post they used to fix this problem. Thanks in advance, a much.

Have you cleaned the IACV? Has it ever been cleaned? That is where I would start. If it has never been cleaned, it probably needs it. Usually a dirty IACV will result in rough idling as opposed to searching. Searching could indicate a sensor or ECU problem. Main sensors involved with rpm control are: engine speed, coolant temp, neutral/start switch. Do your rpm's wander only when driving or only when parked or both? Which engine do you have?

I had a problem similar to yours and it turned out to be bad gas and/or water in the gas. It worked its way out of the system in a few days.

[JV3421]

Thanks first for reading through my question.
I got this car as a used one, 3 years back @ 92k miles. Currently it is 116.7k miles.
So I do not know the MAF, IACV are cleaned. As soon as I bought it, I did do the 90l milestone service @ a dealer, but I doubt they have taken pains to clean them. So I may have to do the cleaning by myself.
I started getting this problem in this peak winter. Couple of times, spaced like 1.5 months apart & then again a week before I posted this problem here.

As artbuc put it here. I was doubting water in gas, but if that is the case, every time it rains / car wash should give me this problem. It is not happening like this.

And reg. the RPM, at higher gas like car speed is more than 35 mph when this problem is occurring, this problem will not be there. Engine will run fine. If I slow down in the signal, my car will be jerking and the RPM meter will be wavering around the normal idle RPM range. I will look for a place to stop my car and switch off the engine & will wait for 45 minutes. After that the problem will be gone. However, with this problem in car I am not able to drive to long distance places with my family having small kids :-(

Looking for TN users / experts to point me to the area where I need to start working on my car.

[mmejia]

Well, from what I see, it seems to be some kind of heat issue since it happens after driving for a bit and only stops if you let it rest for 45 min. I'm thinking it might have to do with EGR. If I'm not mistaken, EGR gets disabled at higher speeds, so that would explain why it only does it when you slow down.

I'm guessing it has to do with the sensor for the EGR. EGR I believe stands for Exhaust Gas Recirculation, but I might be wrong. It's used to run the exhaust back through the intake to lower emissions. I'm thinking that's what is acting up.