Hi, I have an 86 Accord (see below for details) that has a very nasty problem. When I start the car the engine revs up to about 2250. A little high but ok. As the car warms up the idle begins to drop. It gets to about 1500-1600 then rises again to 2200. Then the idle falls quickly and so it begins. The very irratic idle jumping between 1300 and 1800. This is with no load. While driving with load on the engine the car is fine. Without a load the car starts doing the irratic idle thing again until I press the brake and add some load. It used to do it every so often, but now it is all the time. Cold or warm outside. It doesn't matter. Also, I can't get the idle below 1000 with a load. When I had it running right I set the idle so when I had all accesories on and in gear it would idle at 850. Now it is different. Since it is an 86 there are more vacuum lines than the 88-89 model. I thought about the idle air control solenoid, but it didn't make a difference plugged in or vacuum lines unhooked. I think it is an issue with another vacuum system that controls the idle. But I don't know. Any ideas? Similar problems?

Here is a video of it:
http://www.youtube.com/watch?v=6zcZoylKsb0

 

If the idle control valve is sticking, then plugging the vacuum line that controls it will not change the idle.

Try plugging the port outside of the throttle plate with your finger. If the idle settles, then the control valve is stuck. On newer Accords (94+) you can take apart the valve and clean it. I am not sure about an 86.

Another problem could be that your throttle plate is sticking open. You can try to clean it with throttle body cleaner on both sides and around the edges.

 

If you mean the idle air control valve, I unplugged it from power. That didn't make a difference. I also took off both vacuum lines which didn't help. One made no difference while the other allow the car to idle at 3500 and then drop to 1500 in under a sec.

I'll check out the throttle plate

 

I just watched the video. Does your engine always sound that loud?

I don't think that you are getting my point about the air control valves. I put a schematic of your intake on here. #8 is the fast idle valve and #9 is the idle control valve. Those valves open and close to allow air to bypass the closed throttle plate. If they are stuck open, it does not matter if you unplug them. They will still be stuck open. If you take off a vac. line to them, air will still enter into that valve. It will just be unfiltered.

There has to be either tubing going from the valve to the intake tube or holes in the throttle body to get air that cleaned by the air filter. If you can find the holes or tubing, you should block air flow by using your finger. Blocking off both valves should stop the engine.

Your idle variation sounds a lot like it is the FITV #8. Here is a procedure for a 94 accord repair of a FITV. The valve should be similiar in design. You probably will not have to remove the assembly. You can unbolt that plate above #2 and screw that valve in there until it is snug. You might want to spary throttle body cleaner in there to remove any crap that has accumulated in there. http://www.honda-tech.com/zerothread?id=1003988


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Okay. I didn't know there were two different valves. I know where one is. The other like you said is probably near/on throttle body. I didn't notice one thing. The article mentioned FITV, is usually faulty when the engine surges when warming up. I can let my car get completely warm and still have it do it. I'll check out both of them just to be sure.

Yeah, my engine does sound loud in the vid. It's not really that loud when you are looking at the engine. The muffler is the culprit. It is new but they new one is a lot bigger than the stock one. That's what it had before so they measured it and threw that one on. No big deal though.

 

Problem solved. It took about 20 minutes to remove, clean, tighten and replace it. Thanks for the help.

 

I'm glad that it worked out.