Rough idle

[ralphie]

My wife drives a 2000 Toyota Avalon with 85,000 miles, with a new O2 sensor, new plugs, that has a really rough idle, like one or two plugs is missing. When you shift into neutral, the idle rpm goes up and the idle smooths out a bit, but not entirely. When driving along, the engine sounds fine.

Any ideas?

Anybody?

Bueller?

Anybody?

-Ralphie

[pmesfun]

Have you cleaned the throttle body and idle air control valve, particularly the iacv? They like to gum up and cause idle issues.

[ralphie]

I haven't personally, but I think it was done on our last service when they replaced one of the O2 sensors. Nevertheless, I'll check it out.

Thanks for the tip!

-Ralphie

[ralphie]

A little more info:

This started a couple months ago, so I changed the plugs. I put in cheap plugs, but it started running rough, so I put in the Toyota dealer's plugs, (spensive!) and it still runs rough.

When I took out the cheap plugs, I noticed that two of them, (I can't remember which end of the engine they were on), were badly fouled. For a few years now, every time the wife fires it up at the start of the day, a big cloud of blue smoke comes out the tailpipe. I can live with the two or three quarts of oil each week, but I'm afraid that the extra oil squeezing by the valve guides is fouling the plugs. Our local mechanic, (City Garage), wants $1500 to change the valve guide seals, and we haven't been able to afford it yet.

Anyhoo, that's where we stand. I really don't think that cleaning the throttle body and iacv will help. Thanks anyway, pmesfun.

Any other ideas?

-Ralphie

[jk7k2b]

Ralphie, we had a similar problem with my wifes 03 Avalon after she was forced to drive through water deep enough to ruin the carpet padding. Problem started after car was laid up a few days while padding was replaced. Insurance ended up replacing the IAC (about a $500 repair IIRC) and car has been fine since. When we were having the problem, would occasionally get check engine code for 3 plugs misfiring. I also had a sticking throttle problem that went away when the IAC was replaced.
HTH,
John

[ChiTDI]

A rough idle can be electronic, fuel, or vaccuum.
Run as many tests as you can, and get the codes read. Start to narrow the possibilities.