[Guest]

...acceleration,not at idle.whats the problem? If i accelerate slowly,it don't knock.i check the engine oil and its in operating range.

 

[Guest]

Timming off fuel lean engine missing plug wiresnot connected wires wrong on engine cat converter plugged

 

[Guest]

If your timing is advanced... it will also cause a spark knock. Also the octane rating your using could be a bit low... try a better fuel, and check timing... However, if it's a dull thud... or sounds heavy... it may be a rod!

 

[Guest]

before you start doing what the other answers say..{rebuile/new engine] try some high octane gas..you may just have some carbon build up,,,it raises compression causing pinging....i assume its tuned up...right? right?

 

[Guest]

I dont know if this will help or not. My cousins 88 caprice had a knock under accelaration but no other time. I checked and the torque converter bolts were loose. Wouldnt hurt to check.

 

[Guest]

Could be bad rod bearings or a bad knock sensor for the computer. Try tapping on the block with a hammer in the area of the knock sensor when the car is idling...if the sensor is good, the idle should usually change.
http://www.autozone.com/R,LOC4653/shopping/locsSelect.htm
Bad bearings may be helped for a while by using thicker oil like 10W-30 or 10W40 and adding oil supplements like EOS from a GM dealer.

 

[Guest]

Sounds like rod bearings are starting to go. At the begining they will only knock under a hard load, after a while they will knock all the time and get louder. Time to replace the engine before it leaves you stranded.