92 Civic Si low idle

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LSVtecSdn

New Member
OK, so I just bought a 92 Civic Si and the idle is really low looks like 200-300 RPM. I figured it would be the IACV since I know they go on Hondas. I pulled the IACV off my old Z6 that I have sitting around from my LSVTEC build. I also replaced the air filter, new plugs and wires. However, my idle is still low after the car has warmed up. car was bought from well almost 1 owner, 2nd guy owned for short time. it is completely stock! any suggestions would help out it is my DD.
 
there are no other problems except the low idle? No check engine lights, no problems driving the car?
 
correct, it hauls ass when driving just when sitting at light or warm temp, idle is low. I tried adjusting the TB screw the correct way with IACV sensor disconnected, then resetting ECU after adjusting to ~800RPM. no change no CEL
 
Im thinging the IAC may be bad, usually when the iac goes bad it gets stuck in the open position, causing the car to idle up and down but maybe yours is stuck in the closed position, if you have a donor IAC I would try swapping it out to see what happens, because if you followed the procedure and did everyhitng correctly (like you explained above) then you did all you can.
The only thing I can tell is that Alldata says you should adjust the idle to 450 plus/minus 50rpm with No load, ill post the whole procedure
 
  1. Start the engine and let it warm up to normal operating temperature (the cooling fan comes on).
  2. Connect a tachometer.
Electronic Air Control Valve (EACV) 2P Connector
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  1. Disconnect the 2P connector from the Electronic Air Control Valve (EACV ).
  2. Set the steering in the straight forward position, check the idle speed in the no load condition, with the headlights, cooling fan, and all accessories are OFF. Idle Speed (trans in a neutral gear): Manual: 420 ±50 rpm Automatic: 420 ±50 rpm
Base Idle Speed Adjustment
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Adjust the idle speed by turning the adjusting screw on the throttle body.


  1. Turn the ignition switch OFF, reconnect the 2P connector to the EACV, remove the BACK UP fuse in the underhood relay box for 10 seconds to reset the ECU.
  2. Restart the engine, set the steering in the straight forward position and check the idle speed in the no load conditions in which the headlights, blower fan, rear defroster, cooling fan, and air conditioner are not operating. Idle speed (trans in a neutral gear): Manual: 670 ±50 rpm Automatic: 700 ±50 rpm
  3. Idle the engine for one minute with headlights (Hi) and the rear window defogger ON and check the idle speed. Idle speed (trans in a neutral gear): Manual: 750 ±50 rpm Automatic: 750 ±50 rpm
  4. Idle the engine for one minute with heater fan switch at HI and air conditioner on, then check the idle speed. Idle speed (trans in a neutral gear): Manual: 810 ±50 rpm Automatic: 810 ±50 rpm
 
alldata calls the iac an eacv, but whatever
 
well I followed the steps from the super-honda site. I was thinking that it was the IACV also which is most typical vs. the FITV going bad. I swapped the IACV from my old Z6 did not solve problem. I cleaned and tested the FITV even swapped the thermo plunger from another donor FITV, this did not work either. I pulled the FITV again from my old Z6 and VWALLA! problem solved it was a bad FITV.


IDLE is back to normal 750 RPM +/-

Thanks for all the input!
 
OK new update. problem not solved! low idle again at lights it almost sputters a little, I already replace IACV from my old Z6 out of my EX that was running perfect. tach needle set just above 0 RPM only at a stop, if no gas and out gear while rolling idle is fine but within 30 seconds at the light idle gets real low. normal driving, no loss of power or hesitation at all! I changed plugs and wires as well as new air filter, everything on the car is bone stock, no mods.

STUMPED!
 
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