really weird problem

[wockachucka]

Hello all, new here, nice board, and I'm looking for some help with a strange problem I'm experiencing.

My '94 Galant (SOHC, auto, 162k) usually idles around 800 RPM. Suddenly last week it started idling at 1600 RPM, and once it warms up, it will race from 1500-2000 RPM approximately once a second, in cycles. It does this regardless of gear....if you're braked in and in drive, you can hear it idling high, trying to push itself, and if you're take your foot off the gas and coast, and there's RPM headroom, you can hear it racing in cycles. Kind of difficult to describe.......

I don't hear any vaccuum leaks, there were no changes in the normal maintainance routine, and other than that, it runs and drives fine.

Has anyone else experienced this most unusual problem, and what would you suspect are the likely suspects? Thanks in advance.

[gmech]

wock, check for accelerator linkage binding. disconnect the cable from carb and see if the idle speed drops. if so, it may be a binding cable. if not, ensure the carburetor throttle linkage isn't binding and the return spring is functioning properly.

if that doesn't resolve the problem, check the spark plugs, injectors, idle air control servor and compression presiore are all within specs.

also, the ECM should detect any faulty sensors and report it via the Engine Maintenance fault indicator. If this occurs, you can use a voltmeter to read the error code. hope that some help. good luck!