Mechanics

CHEVY SUBURBAN 4X4

1990 Chevrolet Truck

I have an auto trans and about 175,000 miles on it. It has tbi.

2 months ago I did a complete tune up. This included cap, rotor, plugs, wires, and coil.


my questions:

#1 when I first start the truck and drive, the engine knocks like an octane knock. After a couple of min, the knock stops. I have run the gas out of it and put in 2 40 gallon tanks of premium along with fuel additives. This has not solved the problem. Can you adivse a course of action?

#2 The engine runs rough at idle and has some black smoke from the tail pipe. It is like a choke pull off problem with a carb system but it has tbi. I did change the air/fuel mixture sensor on the tbi and this helped just a little bit, but not much. Sometimes, it " catches" and idles regularly, but only for a moment. Any suggestions?

Thank you.
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Dep6point
October 16, 2007.




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