GM Truck Club
THE PREMIER CHEVY TRUCK & SUV FORUM
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Results 1 to 5 of 5
  1. #1

    Default Code P0303 What Could It Be??


    • Hi, I'm new to the forum and don't know a whole lot but am trying to figure my problem out. I have a 96 Chevy Express 1500 with a 5.7 350 in it and it is running really sluggish and is having misfire code(p303-misfire)service engine soon light is on. It started doing it when I was heading up a hill, it just started bogging and has been doing it ever since especially when I give it a lot of gas. I thought was a lifters problem plus rods (i replaced all that) and was no luck problem is still there ,haven't replaced the plugs and wires as well as cap/rotor . I have been researching the common fuel intake problems with the motor and am starting to think I need to clean the injectors (spider replacing ). It has 160000 miles on it . Does anyone have any good suggestions to try anything. Any ideas to what it could be. It seems to idle right and drives ok at the beginning , but when i want the overdrive the hole maracas comes out to play.

      Thank you








  2. #2

    Default

    ****THREAD MOVED****
    To The
    GENERAL CHEVY/GM TECH QUESTION SECTION


    MIKE


    99"SILVERADO
    5.3 l 3.73 l G80
    BLACK BEAR CUSTOM TUNE
    SNUGTOP l COLORMATCH l KATZKIN










  3. #3
    Sr. Engineer
    Join Date
    Oct 2010
    Location
    Indianapolis, In
    Posts
    487

    Default

    I would suspect a fuel delivery problem also. Under no or low load runs fine but give it gas and it falls on it's face? Check the fuel pressure and change the filter for a start. I don't have the pressure specs for the 96.
    2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear

  4. #4

    Default

    P0303 is a mis-fire on cylinder #3.

    It could be many things, I would check the common ones and the simpler ones first. The most common problem is "no spark". This could be a bad plug, a bad wire, a bad dist cap.

    Number 3 is the cylinder that is 2nd from the front on the driver's side.

    Edit:
    Quote Originally Posted by marcos View Post
    ,haven't replaced the plugs and wires as well as cap/rotor .
    as I re-read your post, I think you may have changed the plugs/wires/cap, although, the posts does not read that way.
    Ray

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  5. #5

    Default

    it sounds like was a lifter stuck, but was not i still have the knock, now im looking to change all the , (plugs/cables/rotor-n-cap and ignition ) will be crossing my fingers.
    Thanks for your imput



    Quote Originally Posted by dpeter View Post
    I would suspect a fuel delivery problem also. Under no or low load runs fine but give it gas and it falls on it's face? Check the fuel pressure and change the filter for a start. I don't have the pressure specs for the 96.
    - - - Updated - - -

    i should have wrote code,,,,P0300,,,,MULTIPLES MISFIRES,,Sfor the mistype

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •