Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
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This can be an issue with one or more of the injectors dumping fuel.I have seen stuck open injectors cause this issue in some cases and this will cause the black smoke from the excess fuel as well as the engine to rev up or accelerate on its own.
If you have not had the fuel injectors tested this should be done to see if this is the cause for sure here and any injectors at fault usually require replacement for this issue.
In some cases the engine coolant temp sensor can cause a higher then normal rpm causing acceleration issues and black smoke if it is reading the engine is severely cold all of the time.
These need to be checked into further to locate if one of these is the cause and which is the cause then repaired from there.
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