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  1. #1

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

    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.
    2000 Silverado 1500 5.3
    Z71
    Rough Country Torsion Keys
    2" rear blocks
    Nitro 9000 Shocks
    Bf Goodrich AT's 285/750/16

  2. #2
    Legend

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    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
    99 K1500 Suburban LT "THE BEAST"
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  3. #3

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    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.
    '98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
    '92 Ford Explorer XLT 4x4 4.0 L A4LD BW13-54 Trac-loc rear
    "My toys were the greasy cogs and springs and pistons that lay around all over the place, and these, I can promise you, were far more fun to play with than most of the plastic rubbish children are given nowadays." Danny in Roald Dahl's Danny The Champion of the World

  4. #4
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    Quote Originally Posted by MrShorty View Post
    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.
    X2 also is your Check engine light on?? when was the last time a tune up was completed?
    Mike

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  5. #5

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    what kind of mileage are you getting?

  6. #6
    Master Mechanic Silverado Junkie's Avatar
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    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.
    1995 Silverado,Z71, 3-inch lift,2-inch leveling kit, SkyJacker Suspension, short ram-air intake, throttle body spacer, MSD ignition coil, straight pipes

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