1991 S10 Spark Knocking

:shakehead I have a 1991 S10 pick up truck with a 2.5 vortec automatic engine with 170,000 miles on it. Whenever I put regular gas in it I have a problem with it spark knocking. Can you help me with this please?

You may have carbon build up in the cylinders. Try running a top engine cleaner through it.

I am a woman and have no idea what you are talking about. Please tell me what kind of cleaner you are talking about and where do you put it? Does it go in the gas tank or somewhere else? Also is it possible it could be the EGR Valve causing the problem? Would putting high octane in it help?

Chevy dealers sell top engine cleaner in the parts department. It is better than the over the counter type. You could try a can of it in your gas tank. I will not tell you the other way because you have to know what you are doing or you could damage the engine.

A good repair shop can help you with the top engine cleaner stuff.
Also a repair shop should /will check the EGR valve for working good.
If EGR valve is not working right it will also have a spark knock.
MT