Wandering idle

[hydrosmith]

I have a '95 LX 1.9L with a wandering idle. Sitting at idle every few seconds it will bump up to 1600 from a constant 1000 when it used to idle at about 600. Occasionally on the road it has surged and once almost caused a collision in the parking lot when I pulled into a parking space.

It hasn't turned on the engine light. I suspect the idle air control valve, throttle position sensor or whatever makes the idle kick up when the A/C is turned on (A/C clutch is broken so I know it's not engaging).

It's strange I don't have a trouble code. It has a new fuel filter. The operating temp is normal and the fan kicks on as normal which eliminates a faulty temp sensor(s).

Help, anyone?

Going to get a idle air control valve at the local pick-a-part and try that.
Also I have not found any vacumm leaks.

[Jet-Lee]

I would venture to say its not ur idle air control valve (but im not a mechanic), I've taken mine completely off, and the car ran OK (idled pretty low), unplugged, replugged, no gasket (accident), put on/take off with engine running, but it never went above 1000 rpm. Check other threads, I know I read somewhere bout someone havin the same problem.

[mightymoose_22]

I would suspect if it wre a typical vacuum leak that your RPM's would be dropping rather than surging. The surging problem you describe is typical of a faulty IAC.

[hydrosmith]

UPDATE:

Installed the "new" idle air bypass valve and problem fixed. The one I found at the junk yard was practically new. Even the gasket wasn't dirty yet so I installed that too. Cost: $5 + tax.

Seems to be a common part to fail. Out of ten wrecks I looked at I got the last one.

Thanks for the help.

[Jet-Lee]

my bad, sorry dude. *note to self; next time, keep mouth shut*

[homefree]

I have the same car and troubles with no codes also. I replaced the IAC and plugs, wires, fuel filter, timming belt and cleaned the mass air flow sen. and removed the throttle body and cleaned that, removed the egr valve and cleaned that out with carb cleaner and the DAMN thing still don't know how to idle. Looked for vacum leaks and found none. So i did a compresson test and got #1 cyl 155 #2cyl 175 #3cyl 175 #4cyl 175. The car has 138000 miles on it. Any body have a clue other than junking it???

[mightymoose_22]

You replaced the timing belt.... have you double checked that the timing is set correctly? Take off the timing cover and line up the marks... they might be off a bit.

[Jet-Lee]

your throttle position sensor?