Decelleration

Tiny
PPLAY2006
  • MEMBER
  • BUICK CENTURY
I have a 1991 buick century custom wagon with 192,000 miles.
at about 55 I start decellerating and see a puff of black smoke from muffler. I tried injector fluid in the gas tank and new fuel filter, but still happens. It drives fine in town. Any ideas?[/B]
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Monday, July 31st, 2006 AT 5:11 PM

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Tiny
MIKEYBDMAN
  • MEMBER
When it smokes, does it run rough? Almost 200k in milage, it might be time to check the compression and see how the state of the engine is.
Here is what is supposed to happen in decell:
Deceleration Mode:
When the driver releases the accelerator pedal, air flow into the engine is reduced. The corresponding changes in throttle position and manifold air pressure are relayed to the ECM, which reduces the injector pulse width, to reduce fuel flow. If the deceleration is very rapid, or for long periods (such as long closed throttle coast-down), the ECM shuts fuel completely OFF, to protect the catalytic convertor.

So, I would think that your problem lies in the injectors. If you have one or more not shutting down the fuel, it will load up in decelleration. Although, dont forget to check the engine and see if maybe your not having some ring issues also.
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Monday, July 31st, 2006 AT 5:32 PM

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