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Ignition timing [Expired Topic]

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Davandy, Jun 29, 2005.

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  1. Davandy

    Davandy Moderator 5+ Years ROTM Winner 1000 Posts

    Hi everybody,

    I'm peter from Belgium and I like to ask a question about my Suburban.
    I want to adjust the ignition timing but I don't know how many degrees BTDC.
    In the books I have, they say check emissions label, but there isn’t any on my Suburban. :(
    It’s a Suburban 1993 350 V8 TBI



    Thanks,
    Peter.
  2. TrailLeadr

    TrailLeadr Epic Member 5+ Years 1000 Posts

    Hi Peter, welcome to the club!
    I'm fairly certain that the timing for your engine is 4Deg BTDC.
    There should actually be a label on your air cleaner that tells you the details for your ignition timing.

    Why do you need to adjust your timing?
  3. Davandy

    Davandy Moderator 5+ Years ROTM Winner 1000 Posts

    I'm searching for an answer why my Suburban has no power, and the fuel consumption is outrages 38 L / 100 KM I don’t know it in MPG.

    I can't find the label anywhere, I think it's removed



    Regards,
    Peter.
  4. TrailLeadr

    TrailLeadr Epic Member 5+ Years 1000 Posts

    That works out to 10Gal / 62Miles (for those of us on the SAE, so we can relate)
    Which is about 6 miles to the gallon, or 2.63 km per Litre.

    OUCH!

    Can you give us some more details?
    How many km on suburban?
    How long since last tuneup?
    Where is the loss of power? (Light accelleration, heavy accelleration, throughout entire throttle)
    Does the engine idle smooth or roughly?
    Oversized tires/tyres?
    Any vehicle mods, or completely factory?
  5. Davandy

    Davandy Moderator 5+ Years ROTM Winner 1000 Posts

    Hi,


    There aren’t any modifications made, except removal of the catalyst.
    The tire size is a little bit taller than stock, but not too much. :roll:
    For the rest is everything stock on the engine.
    It has 160000 miles on it
    The automatic gearbox has an electronic shiftimprover.

    Yesterday my check engine light came one giving me code 44 (lean exhaust)
    How is this possible with this high usage of fuel?
    :shock:
  6. TrailLeadr

    TrailLeadr Epic Member 5+ Years 1000 Posts

    You might want to try changing out the O2 sensor (this is a single wire sensor, and the wire is usually black on that model year). it's located just past the Y in the exhaust pipe. If it's the factory sensor, it's going to be tough to get out of there. The sensor itself doesn't cost much since it's not a heated unit. So it's a fairly inexpensive place to start, and probably the only thing that's wrong with it.

    Normally they make a special socket with a slot up the side for those kind of sensors, but if you have trouble getting it out, you might have better luck with a small pipe wrench, but definately use the socket to put the new one in.
    Don't forget to put anti-sieze on the new sensor for the next time. 8)

    Reply back with your reults.

    Good luck! :D
  7. Davandy

    Davandy Moderator 5+ Years ROTM Winner 1000 Posts

    Ok I will try that

    Thanks for the info :wink:
  8. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    I had an O2 sensor go out 3 years ago in a diff vehicle and it was amazing how it affected gas mileage. You would think the engineers would understand that these things go out and they would compensate better for the lack of information coming back into the engine!

    Anyhow, let us know how that works out will you?
  9. TrailLeadr

    TrailLeadr Epic Member 5+ Years 1000 Posts

    Actually the newer ones, I think it's '96 and up (I'll check the books) have more than one O2 sensor. So it's not as bad if one fails, but it still affects mileage.
  10. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    Don't most have one per header?
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