I recently purchased a 1986 Honda accord hatch that has the A20A1 Carb engine in it... But I'm having a wierd issue with an intermittent high idle.

The issue is sometimes when I first start the car when it's cold or sometimes after sitting for a couple minutes after being completely warmed up, the car will idle at around 3,000rpm. If I shut the car of while it's doing this it will diesel pretty bad (normally it shuts down fine). Anyway, I think I can see what is causing this issue is what looks like the throttle linkage (a little tab) is too far away from where the idle adjustment screw is set to. When the car is idleing at 3k it is away from the screw when it idle's normally (1,250 cold / 750 warm) it is right on the screw. I dont think anything is getting stuck open because the throttle cable is slack while it is doing this. What I need to know is what is keeping the throttle open like it is? The choke seems to operate fine (closed when cold open while warm), I dont think I have any vaccum leaks (it's possible though), and asside from that I am stumped. So what controls that little throttle linkage beside the large one (with the throttle cable attatched)... I am unable to move the little tab by hand....

This running at 3k is a very serious problem, especially since my clutch is warn out to the point that it slips pretty damn bad, so having to start out from 3k really isn't helping my clutch. And not being able to shut the car off is also a big problem, because it will continue to diesel, the only way to shut it down when it's doing that is to stall it by popping the clutch (ugh)....

I really, really would appreciate some help with this.. even some advice to point me in the right direction to get me started... What can I test, what controls that little linkage, and why does it only do it once in a while (it's getting worse though)...

Please help!

Thank you!

here is a picture of what the linkage kinda looks like, but it's showing the screw moving, being controlled by vaccum, but it doesnt show anything about the little tab being opened by something else wich is cause the high idle... I just need to know WHAT is opening the throttle!

 

from what the diagram looks like I would say that the vaccum ballast that helps control the throttle cale has gone bad thus causing your high idle issue, also look and see if your throttle cable is binding anywhere.

 

when it is doing that then push the throttle cable to the location it's supposed to be at (where the screw is up against it) and see if that resolves the issue.... you might have a worn hose that is allowing a vacuum leak so it's not setting the high idle properly, inspect all your hoses very closely to see if they are cracked/broken at all and allowing air in (most common location for this is right where they go over whatever they are connecting to or any points where they are bending)

 

I am unable to move the little throttle plate by hand.. looks like it is attatched to a rod going inside the carb.. so i'm just thinking it is sticking inside the carb or something.. I am going to try and clean the outside of the carb with carb cleaner and then also try to clean the inside with carb cleaner.. if i am unable to solve the problem that way i'm thinking the carb might need to be taken apart to resolve the issue.. I'm fairly sure it's not a vaccum issue since it doesnt really have any vaccume lines going to the part or anything connected. should I be able to move that little piece by hand while the car is running?

 

I am unable to move the piece that is indicated by the arrow, it's like it's seized, but it moves when the car is on. What controls this? I believe that is the culprit causing my fast idle (didnt do it tonight, but did it all the way to work this morning.. a 30minute drive!).... any ideas?

 

try tightening the adjusting nut and see if that helps

 

the little screw that is supposed to be the stopper? If I adjust inwards it will speed up the idle, which is fine most of the time... see it's not coming all the way down back to the screw so it's like the throttle is stuck open, but the actual throttle that is controlled by the throttle cable is slack and able to move freely even when it's "stuck" open... I've found out that I can blip the throttle a bit before it gets locked at 3k and it brings it back to the regular idle, so I can get by with it for now.. it seems like there is something that when I turn the car over it gives it a lot of fuel at first but then should back down, but instead it's getting stuck...

 

sounds like the throttel cable is getting hung up somewhere then.

 

Hey I recently bought an '86 accord sedan and I'm having the same problem just not quite as bad. After it gets to normal temp the throttle plate doesnt go all the way back to the screw. I dont know if its just gummed up or what? On your diagram it doesnt show the screw on the back side of the throttle cable(inner side). Im confused as to what that screw does? 2 Idler screws?