1. Welcome To GMTruckClub.com!

    The #1 Chevy Truck Forum Online
    Online since 2004, we are the #1 Chevy Truck & SUV forum and user community. If you have any questions about your Chevy or GMC Truck, SUV or Crossover, or just want to connect with other GM owners and enthusiasts around the world, you've found the best place on the internet to do that.

    Join Today ~ It's Free
    Registering is Free and Easy! Hope to see you on the forums soon!

PLEASE HELP !! DTC P0300 02 sonoma 4.3L

Discussion in 'GM Powertrain' started by BLOWOUT, Oct 5, 2012.

  1. BLOWOUT

    BLOWOUT New Member

    Hello Everyone,
    I have a 2002 GMC Sonoma 4.3L VIN W. It has roughly 130,000 miles on it. Im getting DTC P0300 Random multiple cylinder misfire. I have done everything that I can think of. Here is a list of the things I have already replaced:
    - Plugs & Plug Wires
    - Distributor
    - Distributor Cap
    - Rotor Button
    - Ignition Control Module
    - Ignition Coil
    - Crank Shaft Position Sensor
    - Fuel Pressure Regulator
    - I also took the truck to a GMC dealership and they put a GM Tech 2 on it and tested the injectors and they checked out fine.
    - Also did a Fuel Pressure Test
    - Checked for vaccum leaks

    I am beyond stumped. The only thing I can think of that is left to replace could be the ECM/PCM. If anyone has seen or heard of this and has in info that they can pass along it would be very much appreciated. I forgot to mention the truck doesn't really misfire at idle only when driving. I hooked it up to a MAC OBD II scanner and monitored it. Every time its the same thing cylinders 1 & 4 are almost dead. Thanks so much for any help.
  2. PantheraUncia

    PantheraUncia Active Member 1000 Posts 100 Posts


    This is a general guide:

    http://www.obd-codes.com/p0300

    From looking around google, it could be an issue with a spark plug misfiring. I would check the plugs and cables (again). If you know someone with a diagnostic tool, see if they can find out which cylindar is mis firing.
  3. moogvo

    moogvo Moderator 1000 Posts 100 Posts

    Are you losing coolant over time?
  4. BLOWOUT

    BLOWOUT New Member

    My roommate has an OBD II scanner and its cylinders 1 & 4.

    - - - Updated - - -

    MOOGVO I really havent checked to see if im loosing coolant but i will check it and get back to you thanks
  5. BLOWOUT

    BLOWOUT New Member

    My coolant levels appear to be fine.

Share This Page