Parson

Hello All,

First time poster, long time lurker here. I know that variations of what I am about to ask have been asked multiple times before, but I am not convinced that my problem is related to any of the other posts. I own a 1998 ES300 with 210,000 miles on it. Runs like a dream. Recently I replaced my valve cover gaskets and while I was doing that I also did other small jobs such as the PCV valve, upper intake manifold gasket, spark plugs and wires, clean MAF sensor, clean Idle Air Control Valve, clean Throttle Body, replace 2 or 3 vacuum hoses to various things, and I also replaced the EGR valve due to me being impatient and breaking it when I tried to put it back on without realizing I did not have all the bolts lined up. Anyhow, the job went very smooth and I did not run into any problems, except the EGR valve mistake. But now I am experiencing an inconsistent idle when starting the car that was not there before the job. Occasionally, about once every week, it will start up and idle really poorly around 200 to 500 rpm's. When I give it some gas, the problem sometimes goes away, but not always. My initial thought would have lead me to think that it was the IACV but I am skeptical due to the fact that I gave it, and most everything else, a thorough cleaning before putting everything back together and it seemed to be in good condition. My second thought was that maybe some of my older vacuum hoses had leaks or were not sealed tight enough when I put them back on. So other than the typical "clean the IACV and throttle body" advice, does anything come to mind? I thank everyone for there advice in advance, this forum is awesome!

Thanks so much!!! I hope I did ok for my first post.

Oro

If you did all that, you had a lot of hoses off and possibly one is still loose, unattached, or even broken along its length from age and heat. I'd take the cover off and go back over them all carefully. Make sure you didn't mis-route any of them in the rat's nest of hoses next to the battery and in front of the air box cover.

Parson

Will do. Thanks for the advice. I should probably replace most of my vacuum hoses anyways. They were tightly sealed from age when I took them off, but when I placed them back on they were very loose and slid right on. I was thinking maybe a leak in one of those. After your response I will surely go back through them and replace anything that doesn't seem well fitted or in good shape. Thanks for the advice. I appreciate it greatly.

speedkar9

Since the problem is intermittent, its less likely to be a vacuum hose.
Did you completely disassemble the IAC valve and clean it physically, or did you just run some cleaner through the access hole at the bottom of the butterfly valve?

It is possible that you could have damaged it. Its a little motor that turns back and forth just like a drive by wire throttle body butterfly valve.
A closer look at what it looks like here at 4:06

Parson

I just sprayed cleaner down it. I don't think I damaged it unless spraying cleaner down it could have caused damage to the computer in the IACV.

Parson

Should I physically remove the IACV and clean it?