89 DX carbed idling question

[pink_sleeve]

I know the car is supposed to idle around 800rpm... Mine has idled between that and 1000 for the most part. Now for the past few days the idle wants to stay around 1300 to 1500 and it idles higher and higher the longer you drive it up into the 1800 range ... Any idea what would or can cause this? The temps outside have been down in the 30s and 40s and below for the winter. The last few days have been 50 to 70s and this is when the idle has been acting funny.

[Xaisk]

I know the car is supposed to idle around 800rpm... Mine has idled between that and 1000 for the most part. Now for the past few days the idle wants to stay around 1300 to 1500 and it idles higher and higher the longer you drive it up into the 1800 range ... Any idea what would or can cause this? The temps outside have been down in the 30s and 40s and below for the winter. The last few days have been 50 to 70s and this is when the idle has been acting funny.

I had a simliar issue to this while I still had my stock carb. My problem was I would drive and as I gave it gas it would come back down but not back to idle, it would be slightly above and it would keep going up like 50-100 RPM everytime it happened. Sometimes if I hit the pedal hard to rev it, it would unstick it. I finally got aggravated and took the air cleaner off. The metal plate in the throat of the carb had gotten gunked up and was having trouble shutting properly. A can of carb cleaner solved the issue for me.

[Buzo]

There are a few things that controll the throttle position at idle

1) The accelerator linkage. Check the pedal and TV cables return is free.
2) The automatic throttle controller. It is the vacuum actuator in the passenger side of the car. It is normally extended, so check it is extended when the car is off and it must get pulled as soon as the car builds vacuum, leaving the throttle loose. If the hose has a leak, the actuator will remain extended.
3) If your car is automatic, there is the Idle Boost Controller in the driver side of the car. It gets vacuum when the car is cold or when the car is in any shift other than P or N.
4) The choke. Again in the passenger side there is a piece of metal with several steps and a screw sitting on it. The higher step when cold and the smaller step when the engine is hot.
5) The throttle itself as Xaisk mantioned below.

[pink_sleeve]

Thanks for the info guys. I will try to check those things out tomorrow. However today the idle would not come below 1500 at all and it was jumping from 1500 to 2000. Up and down.

[Buzo]

Thanks for the info guys. I will try to check those things out tomorrow. However today the idle would not come below 1500 at all and it was jumping from 1500 to 2000. Up and down.

So only the 2) and 3) from my list below can cause the intermittent problem you have.

So look straight to the actuators (they both have an screw with a spring to adjust the idle speed) you need to lift the air filter (no need to disconnect it completelly, just lift it with all the vacuum hoses still connected, so you can inspect the actuators).

If your car is automatic I'm almost sure the cause of your problem is going to be the idle boost controller in the driver's side. And the root cause will be a malfunction in the ECU underneath the driver's seat.

Before you buy a new ECU, loose the screws (one at the time) and check which actuator is moving in and out. You can use your car with the screws loose as long as you have good Idle RPMs in P to keep good RPMS in D.

[pink_sleeve]

So only the 2) and 3) from my list below can cause the intermittent problem you have.

So look straight to the actuators (they both have an screw with a spring to adjust the idle speed) you need to lift the air filter (no need to disconnect it completelly, just lift it with all the vacuum hoses still connected, so you can inspect the actuators).

If your car is automatic I'm almost sure the cause of your problem is going to be the idle boost controller in the driver's side. And the root cause will be a malfunction in the ECU underneath the driver's seat.

Before you buy a new ECU, loose the screws (one at the time) and check which actuator is moving in and out. You can use your car with the screws loose as long as you have good Idle RPMs in P to keep good RPMS in D.

My car is a manual....

[pink_sleeve]

Now the car is idling at 2500 and won't come down idk what gives... Any other clues?

[TotaledTL]

...idle boost controller in the driver's side. And the root cause will be a malfunction in the ECU underneath the driver's seat...

Do the ECUs fail in this fashion frequently? Not more likely to be a vacuum line and/or a solenoid?

[Xaisk]

To be honest these old carburetors are such a pain in the ass to repair. Mine eventually started idling up and down from 1500 - 2000 and it wouldnt stop. I couldnt source the problem even after checking every damn solenoid in the car, so I did a weber conversion. Runs like a damned champ.

[pink_sleeve]

Ok i have tried to check the things you guys mentioned with no luck so i decided to manually turn the idle down with the idle screw. The car ran fine yesterday and was idling around 800ish but was hard to start. Now today the car is back up to idling at 2000 to 2500 solid. WTF

[Buzo]

Do the ECUs fail in this fashion frequently? Not more likely to be a vacuum line and/or a solenoid?

When the solenoid is intermittent, switching on and off at a fixed frequency then the ECU may be the problem.
If the issue is always on or always off then the wiring or the solenoids are the common causes.

However, a lot of checks must be done before replacing the ECU, including testing with a known good ECU.

[Buzo]

My car is a manual....

You should tell me that before haha,

The choke or the frequency solenoid C which drives the idle controller remain as a possible cause.

I would leave the idle controller out of the play by backing the screw off all the way, then you may need to compensate your idle speed with the idle stop adjust.

There are two different sympthoms here, one is the intermittent Idle speed going up and down, and the other is staying always up. Two different causes.

[Buzo]

To be honest these old carburetors are such a pain in the ass to repair. Mine eventually started idling up and down from 1500 - 2000 and it wouldnt stop. I couldnt source the problem even after checking every damn solenoid in the car, so I did a weber conversion. Runs like a damned champ.

My car did that to me and fixed it replacing the ECU. A $15 USD fix.

[g.frost]

Did you check, after the engine is warmed up, to make sure the choke is fully open and the fast idle cam has fully unloaded?

[Demon1024]

If you haven't i highly suggest the vacuum removal. Check/replace all the vacuum lines / routes.

[pink_sleeve]

If you haven't i highly suggest the vacuum removal. Check/replace all the vacuum lines / routes.

What are the things on the driver side of the car that the vacuum lines run to up near the fender?

[rocketman]

If you intend on keeping the car I'd suggest spending the $$ for the Weber today. The old Honda carbs (this one is 22 years old!) are such a pain . . . I tried to diagnose and fix mine for YEARS, did anything I could think of . . . finally sent to a Weber, runs GREAT! That was 200,000 miles ago. Rocketman

[g.frost]

You will have to put a technician hat on to actually diagnose the problem. Then read the manual for test procedures. Mine idles at 2000 and 1500 rpm every time I start it cold. When it warms up (more or less....) it idles down. So one good suspect is the mechanism that controls the cold/fast idle.

Do you have a vacuum gauge? Warm up the car, pull off the air cleaner and test the 'fast idle unloader'. (download the manual) Unpug the vacuum line and pump down the fast idle unloader. Does the idle drop to 800rpm? Yes/No? follow the vac line ... thermo valve A, is it open? ...now to the choke opener: do you have good vacuum on line 18 from the choke opener?

My 88 only has 154K miles, but original carb has never been opened. It needed to replace the choke opener and a thermovalve a couple years ago.

[88Accord-DX]

To be honest these old carburetors are such a pain in the ass to repair. Mine eventually started idling up and down from 1500 - 2000 and it wouldnt stop. I couldnt source the problem even after checking every damn solenoid in the car, so I did a weber conversion. Runs like a damned champ.

If you intend on keeping the car I'd suggest spending the $$ for the Weber today. The old Honda carbs (this one is 22 years old!) are such a pain . . . I tried to diagnose and fix mine for YEARS, did anything I could think of . . . finally sent to a Weber, runs GREAT! That was 200,000 miles ago. Rocketman

Both these guys know what I know about these carbs!
Weber is the way to go by far. Lost lots of time fooling with it, cause of how finicky these carbs are with all the vacuum lines & solenoids.. You can only beat a dead horse for so long.

Buzo has some serious carb diagnostic equiptment by far, more advanced for the average Joe.

[pink_sleeve]

Both these guys know what I know about these carbs!
Weber is the way to go by far. Lost lots of time fooling with it, cause of how finicky these carbs are with all the vacuum lines & solenoids.. You can only beat a dead horse for so long.

Buzo has some serious carb diagnostic equiptment by far, more advanced for the average Joe.

Is ebay the only source for Weber carbs or can they be found cheaper then $325?

[88Accord-DX]

I think some other sources are carbs unlimited. I just bought a used one off ebay & rebuilt it for about $150.. The weber is easier to rebuild than the OEM Keihien carb.

[Dr_Snooz]

I believe those Webers came stock on some cars. A little internet research and some trips to the junkyard might be worthwhile.

[pink_sleeve]

You should tell me that before haha,

The choke or the frequency solenoid C which drives the idle controller remain as a possible cause.

I would leave the idle controller out of the play by backing the screw off all the way, then you may need to compensate your idle speed with the idle stop adjust.

There are two different sympthoms here, one is the intermittent Idle speed going up and down, and the other is staying always up. Two different causes.

How do you properly check the choke? I am not all that familiar with carbs Also is there a diagram somewhere so I can find this frequency solenoid? The car still keeps idling around 2 grand and sometimes does the 1500 2000 jump up and down. What can be harmed with it idling this high bc I don't have a ton of money to dump into this fix at the moment and from what I have read you can't use the Weber carb if you have to take an emissions test which I do have to do in about 6 weeks or less. Right now this is my only form of transportation and is only driven 5 to 10 miles at a time. Thanks again for the help guys

[pink_sleeve]

Well I haven't been able to solve the problem and it just idles at 2500 solid now every time I start it. I think the high idle has started to take its toll because smoke just rolls from under the hood now and the whole underside of the motor is covered like it has an oil leak so I'm guessing it'll be going to the scrap yard soon

[TotaledTL]

Well I haven't been able to solve the problem and it just idles at 2500 solid now every time I start it. I think the high idle has started to take its toll because smoke just rolls from under the hood now and the whole underside of the motor is covered like it has an oil leak so I'm guessing it'll be going to the scrap yard soon

Well keep an eye on the oil level. Did you check the pcv valve? Did you dnload the manual & look for the solenoid, idle screws, etc.? The idle controller, solenoid or whatever controls it was part of my idle issue as Buzo said. I just disconnected it & increased the idle w/ the throttle stop screw. Don't just give up & scrap it-