can't figure out this knock/rough idle

[volsmd99]

So last weekend, I was driving back from a trip. About a mile from where I was staying, my car began to hesitate and sputter as it was going up a hill. Ultimately, the car shut off at the top and the check engine light came on. I was able to restart the car, but with it now making a knocking noise. After checking it out at a gas station, I was able to drive it back 200 miles to my house. Guy at autozone said the check engine codes corresponded to a misfire in cylinder #3 and something to do with the MDP sensor.

The car idles fine but with a loud knock. The knock seems to disappear as I rev the rpms above 1500. I replaced the spark plugs but it made no difference. The spark plug wires are about 30,000 miles old so I didn't change these. Also, I disconnected each cable one at a time to see if I could isolate the noise from a cylinder, but it made no difference. The car except for the noise seems to run okay. I've actually been driving it to work every day. Plus, the check engine line has not even come back on.

Does this sound like a bent valve/mechanical or should I continue troubleshooting the electrical system?


1995 Eclipse GSX
170,000 miles

[rottonrattt]

what kind of knock and where does it sound like its coming from?

[david-b]

Agreed with above. Where is the noise coming from? Does it sound like it's in the block itself, in the head, or the trans?

I'm guessing possible bearing since the noise goes away and the motor has that many miles.

[SilvrEclipse]

I would drain the oil and look for metal, it sounds like a spun bearing to me.