View Full Version : Car Idles at 2-3k RPM

04-07-2007, 04:16 PM

I recently bought a 81 Accord 5spd (California Car), and am having trouble with it idling. The car failed smog due to "ignition timing check due to rpm being out of tolerance." But the emission levels passed.

Car has trouble starting, i have to play with the throttle to get it idling otherwise it will just stall. When it does stay idling, the rpm jumps up and down around the 2-3000 range.

Not sure if this has to deal with it, but the car almost overheat when i brought it home going up a hill.

Not sure if this is a problem with the distributor, carb, or something else. I just got my shop manual, so that could help explain any of the technical words you guys get into.

Any help is greatly appreciated. Thanks in advance. :cool:

04-08-2007, 01:08 AM
I'm still a carb noob myself. But my guess would be check for a vacuum leak... I'm sure someone will chime in with a better answer here.

04-08-2007, 10:25 AM
I would guess it is a carb. issue and some kind of vacuum leak "somehwere" as well. Don't go just pulling lines and hoses off, though. These cars are finicky with their fuel mixture/delivery and they will not run well if something is even a little bit off. Being a Cali. car sounds like it might have a few more emissions toys than the regular Accords. I hope your manual is silver and says 1981 on the front; they have the KL (California) specific stuff.

04-08-2007, 03:52 PM
Yes, it is a silver 1981 service manual.

I got the rpm to stop jumping around. When warm it still stays at 2600 though.

What i did was use some better Breeze hose clamps on breather hose A and plugged off the top hose that connects to the Anti-Afterburn valve because i couldn't get it to fit. Why is this hose connection bigger on the Anti-Afterburn valve and gets smaller where it connects at that little piece where 6 hoses connects to?

The car starts and rpm jumps to about 1000 then goes up to 2600 and stays there. Could this mean a problem with the choke? I sprayed choke cleaner at the choke when the car was idling and it almost stalled but rpm jumped back up to 2600 (not sure if i was supposed to spray carb cleaner in there or not...)

When i turn it off the rpm drops all the way down very fast and the car shakes quite a bit.

I'm going to go check the throttle and choke as it explains in the shop manual. :crying:

04-08-2007, 04:12 PM
Sorry for double post. I just realized that if i turn on the headlights the rpm will drop by 250rpm. Is this normal? Or does that mean it is an electrical problem?

04-08-2007, 04:31 PM
On a cold start, 2600 RPM is within mormal limits. After it warms up and you tap the gas, the RPM's should drop to about 900 and it should be smooth. Turning on the lights, the rear defroster, the AC, turning the steering wheel will all put load on the engine and drop the RPM's slightly. Your headlights lowering the RPM's slightly is normal. When you adjust the idle, you should turn on your headlights and rear defogger and adjust it to about 900RPM with those loads. The AC has an idle boost to compensate for all the load it puts on the engine.

Spraying carb. cleaner in the carb won't really hurt anything but it will cause it to idle rough while you spray. Just keep it moderate--a little goes a long way. Does your car shake at idle while in P or while in D? If it shakes in D, it's the motor mounts; it should go away in N or P. If the car just shakes while idling in P, then it's just running rough and something is wrong somewhere.

I'd say start the car, let it fast idle for 5 minutes at 2500RPM, then kick it down and see what happens...

04-08-2007, 06:06 PM
Forgot to mention that the car idles at about 3000. And when i tap the gas after the car is warm it will drop to 2600.

I am going to try covering the carb tomorrow to see if i can hear a vacuum leak.

Edit: The car is a 5spd.

04-09-2007, 01:02 AM
i had this problem with my 88 accord it turns out that it was the evaporator hose or something go get some some carb clean and go get spray happy under the hood and when you hear the engine rev then you isolated the area.... that is if it a vaccum leak

04-09-2007, 01:04 AM
also my other car is a 89 carbie 5sp
when it gets cold even in the summer time it does idle to about 3000 depending on how cold it is then you hit the throttle and it drops to about 2k 2.5k then when you rev it again it tricks the comp and it idles at 1000
try the carb cleaner and then if not try cleaning you carb since you already have it there you know?

04-09-2007, 02:11 PM
US spec cars have Automatic choke don't they? Just to add to complexity & plumbing.

I think I have to look at the idle drop controls on mine (Non CVCC) -drive it hard & it sometimes takes an age to drop below 2000 after taking it out of gear -annoying.

04-09-2007, 05:27 PM
Ok so this is what the choke (i believe) looks like.

Car off.

Car idling at 2600rpm. Lowest rpm it can get.

When it revs the choke closes more... :confused:

04-09-2007, 06:42 PM
Your car, from what I see, looks hella good. This will sound silly, but have you checked your idle adjustment screw AND spring? You would have to remove it CAREFULLY. If someone had been in there before, they may not have replaced the thumbscrew and spring with the OEM stuff. I've seen all kinds of ghetto springs and thumbscrews. This can mess with your idle. Even if the tension of the spring is wrong, the idle will not be right (usually too low though). Also, what is the green connector that is unplugged in the last picture toward the lower right? It looks to be for the master cylinder, but I thought that was 2 separate wires for the low fluid idiot light to kick on. Looks like some other wire is disconnected as well. I would double check to see everything is on tight and nothing is just kinda hanging if you haven't already...

Yes, USDM Accords got the automatic choke setup.

04-09-2007, 07:06 PM
So the choke seems to look good?

This is the idle adjustment screw correct? If so, i let the car warm up and tried turning it, but the rpm did not change much. I only turned it about 1/4 a turn both ways though. Then the fan kicked on, and the manual said to turn off the engine to disconnect the fan, but i couldn't figure out how to disconnect it.

Do you mean that idle adjustment screw can come out completely? So i should remove it and check the spring inside?

The green plug is i believe for the air temperature sensor, which is attached to the whole air cleaner cover.

I did not see the other missing connection. Could you point it out for me?

Also, the distributor cap looks to be replaced. I may have to check that out, but most of you are leaning towards a carb issue. I thought since the smog paper said it failed ignition timing due to rpm being out of tolerance, than it might be the actual ignition timing on the engine.

04-09-2007, 07:20 PM
You're right. I forgot tabout that wire harness on the air cleaner assembly. Duh. That is what the green plug is for. The other wire that didn't look connected (though it could be) is right above the green plug in the picture. I'm talking about the yellow looking wire, and it may be connected to something. That idle screw does come out but be careful and you have it pointed out correctly. Easy to get to huh? You could try turning it a little more to see what happens. I would think it would adjut your idle at some point. If the idle never changes, that may be a problem! I know the spring on my 84 is not OEM and it really messes with the idle; I need to replace the damn spring.

The cap has been replaced and it doesn't look OEM to me. Two things that Honda techs have always told me are finicky are the cap, the rotor,and the thermostat. I guess they see a few "issues" with aftermarket parts that the Honda spec. parts cinch right up. I think it is a carb. issue as well.

I believe there is a plug at the bottom of your fanset (2 cavities as I recall) that will cut the power to your electric fans. The fans will also place a load on your engine and make the idle slightly drop. That plug is kinda hard to reach and I bet it will be filthy. Keep plugging away and you'll get it. I know it is frustrating as all Hell though...

04-24-2007, 06:55 PM
Haven't had much time to work on the car. Now i tried spraying a bunch of stuff with carb cleaner and that didn't help. I did turn the idle adjustment screw out and got it to 1500rpm. I took the screw out but don't know what to see if it is good or not. Put it back in barely a few threads and 1500 is the lowest i can get it.

Any other ideas?

04-25-2007, 10:26 PM
Isn't there a high-idle thermovalve that keeps the RPMs up until the car warms up? And if that goes bad, can't it send vacuum signal that the car is always running cold? Thus leaving the RPMs up all the time?

04-26-2007, 03:21 PM
I'd check for a bent or binding throttle linkage or an over adjusted (tight) throttle cable.