Won't idle correctly

[sander112]

I have a 2005 Honda Accord EX 4 cyl. The problem I have is that it does not idle correctly. It bounces anywhere from 1500 to 500 rpm till it dies. It will do it with or without the A/C on. I was told it was either the rotary air control valve, Throttle position sensor which is riveted to the throttle body or main fuel relay. Does anyone know which way to go on this. I did notice that the RACV had anti-freeze in the 2 lines that go to this?

[jeffcoslacker]

TPS usually will cause idle to be too high or too low, not rolling idle, and the tranny will usually react with screwed up shift points too, so I doubt that's it.

The thermostatic idle valve is likely, if it sticks it can do this...also if coolant is low and surging through it can cause this too.

Temp should be the same in the two coolant lines....if one's hotter than the other suspect blockage or air pocket and coolant surging...

[jeffcoslacker]

The IACV could be sticking too.

Other suspects: Massive vacuum leak, check EGR, PCV, etc.

[sander112]

What is the IACV? There is not any air leaks, Egr and the Pcv are good. Now it will start, idle for about 30 sec. and die with or without A/C. Also I did pull the Rotary air control valve off and cleaned it along with the Throttle body.

[jeffcoslacker]

There's a metered plunger type valve that's controlled by the PCM and regulates airflow bypassing the closed throttle plate in the same way an EGR meters exhaust to the intake.

A carboned up pintle or bore can keep it from moving smoothly and cause them to hunt for idle like that...

Also check to be sure the throttle plate is not simply sticking open slightly due to varnish or interference. Spray the plate clean with some spray cleaner and verify it drops all the way to the base idle stop when closed.

Did you check coolant level? I don't know if there's any bleeders on the system on your year...

[sander112]

If your talking about the valve thats mounted below the throttle body, it's the rotary air control valve. That's what I removed and cleaned up. It has a port in front of the butterfly and when I had the throttle body off I cleaned and checked the for varnish. I went ahead and got the Purchased the rotary air control valve, it's seems like after I messed with this that everything got worse. I'll post tomorrow and let you know if that worked. By the way the coolant level was full along with the reservoir.

[lamehonda]

I always start by checking the airbox to make sure it doesn't have a mouse nest in it. This happened to my mother. The Jeep wouldn't idle for nothing. hope you already fixed your problem

[sander112]

Well I changed the idle air control valve (or rotary air control valve) sometimes it will hold a constant 900 rpm and sometimes it won't. When I put it in drive or rev. it drops to below 500 rpm causing it to spudder. But once it gets going it's fine. Anyone have any ideas what it might be. I thought about the main fuel relay but you would think it would do it all the time, meaning at any rpm?

[jeffcoslacker]

Hmmm...my '95 uses both....the thermostatic controlled under the throttle plate you replaced, and an electric one that sits on the back of the manifold...



I think the one you replaced controls cold fast idle but the electric one regulates base idle mixture...

I haven't looked at an '05 lately so I don't know if it's set up differently...

[sander112]

The one I replaced doesn't have any lines to it, It has 3 ports one for coolant, the other 2 are for air flow over the valve. What it seems like it is doing is that when it gets heat soaked, that's where the idle problems start.
When the fans are not running it runs fine. But when they turn on, the idle drops below 500 rpm. I looked around for the thermo air valve and cold fast idle. I'm assuming the cold fast idle is on the throttle body and the thermo valve is? I looked on the intake and exhaust manifold and couldn't find it. is what you have in the above picture is what it might look like?

[jeffcoslacker]

http://www.superhonda.com/forum/f55/...oblems-259965/

See if you see anything helpful here...it shows both valves and describes the function.

FITV is the proper name for the valve I think you're talking about...I couldn't remember. Fast Idle Theremostatic Valve...the IACV is a seperate deal...they work together. if yours is different, then I'm no good to you...

He describes each and how to check them...hopefully it applies to your year still.

[jeffcoslacker]

Originally Posted by sander112

is what you have in the above picture is what it might look like?

Yes this is a pic of the IACV for my '95...it's typical of what all IACVs look like...

[sander112]

I found on another forum last night that someone with the same year, make, and problem. He took it to the honda dealer and they changed the engine coolant temp. sensor for the low idle when warm or heat soaked. But I guess if you have to take a reading for a hot engine (hot idle, water temp. sensor) and a cold engine (cold idle, IACV) it kinda makes sense. I looked for the intake temp. sensor and couldn't find one. I looked for it in a I.P.C. and couldn't find it. I also found a wiring diagram and it shows the water temp. sensor used for engine idle. Plus it's only $25.00. But wouldn't you know that nobody stocks it on Sunday!!

[sander112]

Here's another good t/sing website.

http://www.askmehelpdesk.com/cars-tr...tml#post842969

[sander112]

We''l I performed the idle learn proceedure and it seems like everything is good. I have driven it for the past 2 days with no problems. But I am going to go ahead and change the water temp. sensor as a precaution. So I would say to if you have this problem change the IACV, perform the idle lean proceedure, and maybe change the water temp. sensor.