1991 Honda Accord Logo
Posted on Apr 02, 2009

Erratic Idle problem in 91 accord

Hi, I start my 91 accord and will idle high for about 5 seconds then starts reving up and down between 1000 and 2500 rpm. I cleaned the IACV throughly and nothing. Changed the TPS (and throttle body) and nothing. Also turned the idle adjust screw both ways and nothing changed. Please help :(

  • Anonymous May 19, 2009

    The idle problem will continue even when it's warm. I does not stop whatsoever. Another thing I noticed is that the fan starts and stops erradicaly when the car is off and warm. Could this be a computer problem, or maybe a thermostat? Thanx for the help.

  • Anonymous Mar 16, 2014

    so my car idles high about 1400rpm, i can disconnect the connectors to the air regulator and the idle air control valve and no change, the ignition timing is set, ive cleaned the IAA unit. car runs and drives fine with power, just idles high with adjustment screw all the way closed. also no change in idle while rotating adjustment screw with tps disconnected. i can warm the car up, shut it off and block off the end of the tube that runs to the air regulator and iacv and on plastic intake tube, the idle goes down to 1000 and sits between 1000 and 1200..my question is witch valve is my problem and is that even my problem..

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  • Posted on Apr 03, 2009
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THE DISTRIBUTOR WILL CAUSE THIS PROBLEM IN A HONDA TRY A KNOWN GOOD ONE .

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Its a sensor for cold starts that fails idles normal after it warms up.

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There is three things that will cause this problem. 1) cold idle valve 2) idle bypass screw 3) vacuum leaks. The most common is the cold idle valve. Looking at the top of the intake, next to the iac valve, you will see a brass colored cap with two screws holding it on. Remove the cover, and using a flat-tip turn the plastic valve seat all the way in until it stops. (it will push against the brass pintle, like it's supposed to). These loosen over time and basically create an internal vacuum leak. Too much air coming in at idle causes the idle fluctuation. Which brings me to item 2. If that didn't fix it, check the idle air bypass screw on the t-body. It should be set about 1.5 - 2 turns from closed. Check for vacuum leaks anywhere between the intake hose and the head. (check the brake booster too) Good luck!

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This will help.

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I just brought a 91! Accord ex. It needs alot of work I am having a problem with the idle its about 2000rpm adjusted but can't get it down please help

usually a high idle condition is caused by a large vacuum leak.start engine open hood an put ur ear in the engine compartment,listen for any loud sucking sounds ,wiggle vacuum hoses an listen for a change in the sucking noise,usually a telltale sign that youve found it wen the noise changes.also u could have a bad idle air control motor which adjusts an keeps idle around a 1000rpm at idle.i highly recommend gettn ur engines computer scanned for any related codes. a good basis to start ur correct path to diagnosing ur idle issues. good luck hope this helps
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