I seem to have an idle problem with my car ('88 Accord LX, 5-speed, carb). When it starts, the idle goes up to about 2000-2200(normal for a cold engine). But after it has warmed up, and I am sitting at a light for example, the idle might anywhere between 1200-1800 RPM. It doesn't rev up or down or anything, it just seems to randomly pick an idle speed somewhere in that range and stay there until I go again. On a rare occasion, I may come to a light and the idle will drop to around 800 RPM(normal idle), but it runs a bit rough. I got lucky when I bought the car and because it came with all the maintenance records. It was taken in to diagnose a "running rough" and "idles high" condition, but none of the repair bills say what was done besides a tune up (which also doesn't tell me if the problem was ever fixed... apparently it wasn't). It's not a huge issue, but I would like to save a bit of fuel, and every once in a while it diesels, making me have to slowly let the clutch out to kill the engine. And I don't really feel like wearing out my clutch over something like this. Anyone have any ideas how to fix this? Sorry if this is a re-post, but I checked the DIY section and the only "surging idle" thread applied to 90-93 accords.

 

chk the accell cable make sure that it is adjusted properly , the reason that it diesels is because idle is too high when you try to shut the engine off..
as for the rough idle .. chk the pcv valve i have seen a bunch of them go bad and cause rough idle ,, but it could also be a vacc leak or internal carb issues

 

The choke can also cause a high idle.Choke platemay be sticking closed. You need to make sure the choke plate is opening as the car warms. Remove air cleaner and observe. Some choke lubricant may fix the problem or cleaning w/ carb cleaner and lubricating.

good luck

 

OK, I started the car and letit warm up and observed the choke plate. It does not appear to be opening or moving at all. I sprayed it with carb cleaner and moved it around a bit, but that doesn't seem to have fixed the problem (maybe I just need to use more or clean it better?). Are there any external linkage arms that may be sticking? I have not removed the air cleaner box since I did not want to disconnect any vacuum hoses that may be attached to it. Any more advice??

 

You need to figure out how the choke is driven open as car is warmed. It could be vacuum actuated, or a coil spring driven actuator.

Suggest downloading the Accord manual from hondahookup.com, "Honda Accord Secan Shop Manual 1986-1989 (31.4Mb PDF)". I hope you have a high speed modem, or perhaps pick up a Haynes manual.

good luck

 

Thanks, I will look into that. The engine seems to idle down nicely when I manually hold the choke open (it could still use a tune up I think). Thanks again, I'll update after I get a chance to work on it again.

 

OK, finally got some time to look into this. I removed the air cleaner assembly, and one of the vacuum hoses leading into the choke diaphragm was cracked completely off. I replaced the hose, but still get a high idle. I looked at the manual in the link TexasHonda gave me, and it says that with a warm engine, the choke should be open something like 1/8", but mine looks completely closed. WhenI start the car, the choke is closed, and it does not even move or open up at all as my engine warms up. I can move the choke diaphragm linkage by hand, which opens the choke to the correct 1/8", and the car idles down, but the linkage won't move on its own. The link below shows a diaphragm exactly like the one on my car.

http://www.autopartsworld.com/Part.a...hoke-diaphragm

Does it sound like the diaphragm could be the problem?

 

Diaphragm amplifies the force from the vacuum supply. You can check by sucking on a vacuum line attached to the diaphragm. If it is ruptured, you will suck but no vacuum will be produced because air leaks through the ruptured diaphgram. If it's intact, it will hold vacuum as you suck. A hand vaccum pump w/ a gauge is more precise, but manual method will work also.

Let forum know what you find.

good luck

 

Allright, update time. I tried the manual method, and the choke opened somewhat, but not completely. The choke linkage moved up to the point where it met resistance, then I started to suck air and the linkage moved no further. While I was at it, I set the proper tension on the throttle cable. That was not causing the high idle, but I thought I would check it anyways. Any ideas? Thanks for following up on this for me by the way. The help is appreciated since I have not had much experience tuning a carbureted car.

P.S. When I take of the air cleaner cover, there are two little metal things inside that look like sensors. They are attached to vacuum hoses that are connected to the bottom of the air cleaner tray. One says NTC1 and the other says NTC2. Any idea what they are? No big deal if you don't, just curious.

 

OK, it has been a while, but since winter is approaching, I am back to work on getting this solved. A few weeks ago, I gave the car a tune up, replacing the distributor cap & rotor, plugs, plug wires, and PCV valve. I also replaced a few vacuum lines that were cracked. Here are two situations that I have noticed that may help with diagnosis:

1) When I am approaching a stop sign, I hit the brakes(obviously) and push in the clutch pedal. The engine speed drops to ~1000 RPM. The engine speed stays there, until the vehicle speed slows to 10 or 15 MPH. When the vehicle speed passes through 10 or 15 MPH as it slows down, I can hear an audible click from under the dash(sounds like the click from the main relay when you start the car), and the idle speed jumps up to 2000 RPM. Is there some kind of solenoid or thermovalve that could be malfunctioning?

2) Yesterday I started the car and let it sit and come to operating temperature without touching the gas pedal. It warmed up and it idled at ~1000 RPM, which is not correct, but would be acceptable. I then got in and revved the engine, and the idle sped up to around 2000 RPM and would not come back down. Does this sound like a throttle cable problem? If so, where can I get a new one?

This is beginning to sound like it could be a combination of a few problems, which given the car's age(20) and mileage(164,000) wouldn't surprise me. I know this may be difficult for you guys to give opinions on since you are not here with the car, and instead have to translate my descriptions. But I appreciate your help since it does give me some direction to fixing this. And I would rather do this than spend a boat load of money by dropping it off at a mechanic. Thanks again.