I have a 1995 blazer 4.3 w engine code. I have a knock in the motor,the engine oil gets black quick 150 miles, the exhaust fumes are strong at times, i have a engine code that pulls up low voltage on ox sensor bank 1 sensor 2. It runs well but sometimes idles rough. My mile per gallon are still ok. Is it the spider that distributes the fuel ? Brownie

 

well im not expert but before i had replace my ox sensore(i got the simialr if not same error codes) my truck ran like it was on its last leg but when i replaced them(even though one can run up to $300) it ran like new with a 8-9sec 0-60 time

i had simialr problems before i replaced it as well

 

I forgot to mention i have already changed the o2 senser but nothing changed.I sometimes have a lot of black soot coming from the tailpipe. The engine noise is more like a lifter sound. Thank for any help.

 

the knock is most likely the rod bearings so its basically worthless to do anything else to the vehicle if you dont fix that..if you drive around with a rod knock it might go threw the engine block


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before you consider the engine toast get out a piece of steel about 3' long. Place one end on the engine and the other end next to your ear. Find out exactly where that knock is coming from.

black smoke would be from an imcomplete combustion burn. Which could be as simple as a tune up. That woudl also explain the gas odor, its not getting burned. You got any gas in your oil?
verify your timing is correct as well.
Rod knock is pretty obvious, and it doesnt mean you will have black smoke. My '93 spun the #1 rod bearing, it knocked like hell, it still drove, but it knocked like hell. Also not smoke. Butit knocked like hell. Did I mention it knocked really bad.

 

It sounds like it is the loudest under the intake. I dont think it is a rod. The oil does have a little of a gas smell. I have changed the wires, cap, rotor,and plugs. I have not checked the timing. Thanks for any input.