idle problem

jorcool13 · Post by **jorcool13** » May 22nd, 2006, 1:54 am

I have a 1994 1.6L DOHC and when I come to a stop thet I hit the brake the rpm starts going up and down, up and down from 400 to 1200 RPM's.
Please Help! Thanks!

MechaManZero · Post by **MechaManZero** » May 22nd, 2006, 1:59 am

Maybe it is the Idle Air Control Valve. They are supposed to raise the Idle at a cold start but when they get all messed up they seem to become all discombobulated.

ariesdude · Post by **ariesdude** » May 22nd, 2006, 5:26 pm

There could be many reasons for the idle jumping - some of the main reasons are
-Vaccum leaks (the air hose might have cracks or some of the clamps might be loose)
-Weak alternator (it cant supply the power needed for the brake lights - so the engine tries to rev up to compensate)
-Bad Ground (it is similar to the weak alt - the alt needs to push more current to overcome the bad grounding)
-Dirty Throttle body (the throttle body might have caked up dirt that is preventing the valve from closing fully)
-Bad TPS adjustment
-Bad coolant temperature sensor
-Bad O2 Sensor (engine starts acting funny after warmup & poor mileage)
-Bad IAC valve