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How to tell if your truck is burning rich or lean.

Discussion in 'Performance & Fuel' started by LSU, Apr 17, 2010.

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  1. LSU

    LSU New Member

    Hey guys I have a 2000 Z71 Silverado and am getting horrible gas mileage. I know its expected to get horrible mileage but my exhaust smells weird and i was wandering if there are any easy ways to tell if my truck is burning rich without taking it to the shop and dropping some money.
  2. vncj96

    vncj96 New Member 1000 Posts 100 Posts

    One way to tell is when you floor it, if you have a buddy behind you he will see some black smoke come out the pipe (not like a diesel) but you should be able to see a quick puff. Its not a sure fire way but it is free non the less
  3. MrShorty

    MrShorty Moderator Staff Member 1000 Posts 100 Posts

    Some say one of the best ways to tell what's going on in the engine is to pull the spark plugs. Most manuals, and a few places on line, have a series of pictures that show what spark plugs look like under various conditions.

    On these OBD-2 engines, you can hook up a scanner to the computer and look at the short and long term fuel trims. Assuming the O2 sensors are working correctly, these can tell you if the computer is needing to add significantly more or less fuel than expected.

    Can you describe the smell? A sulfury smell is associated with a rich engine (the excess fuel is doing something with the catalytic converter to create the smell).

    As noted, a rich running engine also often has a black, sooty exhaust.
  4. murdog94

    murdog94 New Member 1000 Posts 100 Posts

    X2 also is your Check engine light on?? when was the last time a tune up was completed?
  5. duckduckdog

    duckduckdog New Member 100 Posts

    what kind of mileage are you getting?
  6. Silverado Junkie

    Silverado Junkie New Member 100 Posts

    Hes right, they do blow a tiny amount of black smoke when there running rich. When i was jetting the carbs on my Raptor 660, i got it too rich. So when you would punch the throttle to about 10,000 rpm it would make a little puff of black. So i just lowered the carb needles one position and it corrected the rich condition. I know this dosnt help but I am just sayin.

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