1991 Honda Accord idealing to low

Tiny
NIDAL_2
  • MEMBER
  • 1991 HONDA ACCORD
Engine Mechanical problem
1991 Honda Accord 4 cyl Two Wheel Drive Manual

hello,
my car's rpm is dropping below 500rpm when ever I stop I have already changed the ideal valve and motor tried tunning the car to the specified and it didn't work. When it starts dropping below 500rpm I remove the the plug from the ideal motor the rate is below the specified I will try to regulate then resetting the acu it will work for some time then again I will have the same problem. Plz I need help any ideas
thanks
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Wednesday, September 22nd, 2010 AT 8:48 AM

8 Replies

Tiny
KHLOW2008
  • EXPERT
Hi nidal_2,

Did you clean the throttle body and idle adjust screw before setting the idling speed?

Does turning the idle adjust screw increase the idling speed?

Does idling speed decreases when the A/C is turned on?

Have you checked the valve clearances?

Was the IAC replaced new or used?

Are there any trouble codes?
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Thursday, September 23rd, 2010 AT 10:24 AM
Tiny
NIDAL_2
  • MEMBER
Thank you for the fast assistance,
no ididn't clean the throtle body nor the adjust screw. The idle adjust screw will increase the idling speed but as I told you it will drop again after some time and it is more rough when I put on the AC. The iac was replaced used and I didn't check the valve clearences however i'm hearing a little valve knock after accelerating over 3000rpm. When ever i'm driving up a hill. I would appreciate any diagrams on cleaning the throtle body.
Thanks
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Friday, September 24th, 2010 AT 9:04 AM
Tiny
KHLOW2008
  • EXPERT
There are no diagrams to show you.

Remove the air cleaner hose and spray some carb cleaner into it. Use a rag to scrub the inner port with throttle plate opened fully.

Remove the idle adjust screw on top of throttle body. Spray carb cleaner into the idle adjust port and allow to soak for a few minutes.

Clean the idle adjust screw and reinstall. Turn screw fully in and back out 1/2 to 3/4 turn.

Start engine and allow to warm up and readjust idle speed if necessary. Engine might require some cranking time due to the presence of carb cleaner.
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Friday, September 24th, 2010 AT 10:42 AM
Tiny
NIDAL_2
  • MEMBER
Hello
i cleaned the throtle body and till now it appears to be working fine but I found to the left side of the battery a broken hose from a plastic black 10cm*5cm box which has some kind of valve with a 2 wires connector I fixed it I am wondering would this have anything to do with the problem.
Thanks.
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Sunday, September 26th, 2010 AT 11:53 PM
Tiny
KHLOW2008
  • EXPERT
Any vacuum leakage would increase the idling speed and not decrease it.

The black box and solenoid that you are referring to must be the air resonator solenoid control valve. It is for reducing resonance noise and is not related to the idling speed.
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Monday, September 27th, 2010 AT 1:14 PM
Tiny
NIDAL_2
  • MEMBER
Hello,
it seems that the same symptom is back but not as rough as before no error codes any suggestions by the way recently I changed the 2 timming belts and all the seals and after starting the car every thing is ok but when ever I accelerate I hear a humming like sound and when releasing the sound will go any suggestions
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Wednesday, October 6th, 2010 AT 12:18 AM
Tiny
KHLOW2008
  • EXPERT
Check the drive belt tension. If they are adjusted too tight, they can cause humming noises.

As to the erratic idling, when replacing the timing, were the valve clearances checked/adjusted?

Did you clean the IAC before installation?
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Wednesday, October 6th, 2010 AT 8:39 AM
Tiny
NIDAL_2
  • MEMBER
Hello,
i didn't check the valve clearance but the problem of erratic idling was before I changed the timming belts and the iac was cleaned by the way yesterday I removed the two wire connector to check the idle speed I found that it was again below 500rpm I disconected the hose going to the black box I reffered to before the idle speed will rize the hose connected to it has the no 8 written on it plz advise
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Thursday, October 7th, 2010 AT 12:05 AM

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