Running on 3 cylinders

Hi,

My 92 Tercel seems to be running on 3 cylinders. I just replaced the distributor cap, rotor, spark plugs and wires, but didn't seem to make any difference. While the engine is running, I pull the spark plug wire off the number 3 cylinder, but this doesn't change the engine rpm.

Any ideas what it good be. Yes I know that this car should be by dead now -- it has 350,000 km (220,000 miles) on the odometer.

First i would see if #3 is sparking. You can get a tester or just put a VOM or multimeter to see if any juice is getting to it. Or the old - lay it next to a ground trick and look for spark.

If it is not getting spark, then i'd suspect the dist cap, its contacts broken. Or a bad plug wire. But if the other 3 are sparking then it should be getting voltage too.

So if it IS getting spark, then do a compression check on all 4. And if the compression is ok - WTF - then i'd guess i would suspect the distributor because why would only this one not get spark.
But if the compression is low in just this one, put in some oil in the plug hole and do it again. And if the compression reading comes up then the rings are bad in only this cylinder, if the reading is unchanged you maybe need a valve job.