Joint the club, my Legend started doing that from time to time after I did the head gaskets.

I was told that these sensors might be responsible, but I haven't done anything to remedy the problem as of yet.

 

Thanks for your input. Any idea exactly what those sensors are?

 

I haven't checked into that yet; this isn't something I lose sleep over so I've been somewhat lazy about fixing it. But if you do come up with something then I would appreciate it if you share with me. I've read all the idle threads as-well and none of them have given me an answer.

 

So yours also does it, only when the engine is cold? And surges above 2000 RPMs? Then it is fine when the motor is warmed up?

 

Are those down under the air filter on a SR intake? If so, I always thought they were AutoTranny solonoids?:dunno: :headscrat

BTW, yesterday mine was acting weird too. Could it be a full Moon???????

 

I believe they are, but a friend of mine had this problem years ago and he said that replacing those solved it. Personally, I have no idea how they would affect the idle. And I'm 100% sure I don't have any air in my coolant.

 

I just think the coolant has X amount of air trapped in it and needs to be bled a few times till it's ALL worked out.:dunno: :dunno: :dunno:

 

But, wouldn't the surging idle be at different times, not just when my motor is cold?

 

Mine does that....Dont know what it is....

 

mine was doing that and it ended up being a leak in the egr system, just put ur hand back there while its idling and see if u feel any exhaust leaks. Its worth a try since its so easy to do, it will only take u a second.

 

Would I have that with a block plate installed???????????

 

LSman its the idle control valve sensor thingy. a lot of legends do it, most of the time it happens when the engine is not really hot yet, like say you start her up drive a short distance and put her in park you get the idle surging/reving up and down.
it happened to me quite a bit in the winter but in the summer it does not happen.

 

It sounds like a vacuum leak to me, but usually vacuum leaks happen all the time. It's possible your IAC is sticking on occassion.

Those solenoids posted above control the VIS. I don't think that would cause your problem.

Here's something I might try, since it's just happening once in a while. Disconnect the battery for a few seconds to reset the computer, then start her up and bleed the cooling system again. It might just work.

 

Thanks guys. I'll keep everything said in mind.

 

I agree with Mike's suggestion. You may notice that no air is coming out of the bleed screw initially when the engine is cold. If that's the case, I would let her warm up and try again.

Also, it may sound silly, but check your radiator cap and reaffix it if possible (just to make certain it's seated correctly).

Good Luck,
Keith

 

Thanks. I have not tried anything yet.

Mine does it just right after starting it and then stops after it heats up. I don't know why though.

You are like the 2nd or 3rd person to say that. Doesn't anyone care about their cars?

 

Mine does it just right after starting it and then stops after it heats up. I don't know why though.

 

is the fast idle valve or sensor what ever they call it. its purpose is to heat up the carfaster by raising the idle to near 2000 rpms, but they fail as they get old on legends and they malfuction by surging back and forth. it has nothing to do with air in the system. and it will not harm the car at all. my mech said he can either replace it for around 200 bucks or block it somehow.