Contingency

I just got a 1996 Honda Civic LX. It had been sitting for awhile and I have been doing a lot of the basics such as:

Replaced Spark Plugs & Spark Plug Wires
Replaced Fuel Filter
Flushed Radiator
Changed the Oil
New Battery
Couple new hoses

Any ways it runs good but after it warms up it idles weird. It will idle up and down and alternate from higher RPM to lower RPM and I have no idea what the issue would be or how to fix it. So any ideas would be greatly appreciated.

COSMOE CRAMER

Do your lights get brighter and dimmer with the idle, or as you drive at night as well?

gearbox

iTrader: (95)

usually idle hunt means bad tps. could also be a possible issue with the idle air or fast idle valves getting stuck.

LittleBlueMonst

My92 si had head job, also had replaced Ecu last year, new belts and hoses (silicon), shunk2pro intake, 4:1 exhaust mani, catback, new plugs, timing belt, fuel pump, iac valve. Last week, Throttle body plate seemed to stick a bit but wd40 fixed that. Seafoam cleared a bunch of crud. Also cleaned out throttle body. Cooling system flush and new fuel filter followed. Still some idling fluctuations. On the road it sputtered and died from lack of fuel (on the interstate in the middle of nowhere). I have already been stranded in Nowheresville for 3 days til a shop opens Monday morning. (thnkful for my solar phone charger). So, Any bets on TPS as culprit? If not that, what??? I am not a gearhead, just a gal who loves her LittleBlueMonster. Help me guys: Sos.

tlee808

I have the same problem with the engine idling high then suddenly dropping then going back high and repeating the cycle. Then most likely cause is a vacuum leak. There can be many causes for a vacuum leak. One of the most common is the IACV (Idle Air Control Valve). There are 2 checks you can do. First is to unplug the IACV. The idle should drop if there is no other problem. If it does not it could be stuck open or there could be a vacuum leak some where else. The second check you can do is to take off the air filter and put your finger over the IACV hole in the throttle body. You should feel a strong vacuum. If you cover the hole the idle should drop, if there is no other problems. If you cover the hole and the idle still runs high you probably have a vacuum leak somewhere else. The reason the idle goes form high to low and back again is because the ECU drops the high idle but the vacuum leak causes the idle to rise again and the cycle repeats itself again. In my case the IACV seems to be stuck open. A cheap way to get around this is to cover the IACV hole which will bring you idle very low and to raise the idle back to normal by adjusting the throttle (gas pedel) cable.