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97 2500 running like crap

Discussion in 'Chevy Trucks' started by chris694205, Oct 23, 2011.

  1. chris694205

    chris694205 Senior Member
    Messages: 175

    hello all,

    My back up plow truck is a 97 2500 silverado with the 5.7. I did a tune up on it a while back but it still seems to run like crap. Runs decent when its cold and great at full throttle but when your just cruising around it misfires like crazy. No service engine light yet. Any ideas?
  2. chevyzrule810

    chevyzrule810 PlowSite.com Addict
    Messages: 1,288

    I'm thinking its the map sensor.What did you do for a tune up,plugs,wires,distributor cap? I've heard that aftermarket distributor cap and rotor aren't as good as OEM and crossfiring can sometimes happen.My advice is replace parts with acdelco and you shouldn't have a problem.
    Last edited: Oct 23, 2011
  3. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    huge problem with the vortec's is cap/rotor get nasty moisture build up.

    also vary sensitive to plugs. use only the orignal style and # acdelco's

    trust me on this 10+ years doin it as a mechanic and personal vehicle.
  4. kimber750

    kimber750 PlowSite Veteran
    Messages: 4,681

    I would guess mass air or throttle position sensor. Since you said it will run at full throttle.
  5. chillman88

    chillman88 Junior Member
    Messages: 17

    Last edited: Oct 24, 2011
  6. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    if you pull the dist then you will need a specific shop style scanner to reset timming. not a parts story cheepy.
  7. chillman88

    chillman88 Junior Member
    Messages: 17

    If you get it back in where it was, you should be fine. the dist. in these is almost non-adjustable, and timing is all computer controlled. I've had mine in/out many times, but it only runs nice in one certain tooth. (the engine swap was fun, tooth by tooth till it ran) Your results may vary though. if you're anywhere near Seneca Falls, I may be able to hook you up with someone who has a GM Tech II who could set the timing for ya.
  8. 2COR517

    2COR517 PlowSite Fanatic
    Messages: 7,115

    What brand plugs did you install, and what gap?
  9. Plowtoy

    Plowtoy Senior Member
    Messages: 929

    I have gotten about a year out of an aftermarket cap (napa) before they start causing no start and misfiring issues. I would go right to the dealer and get a OE cap and your problems will most likely be gone.
  10. Holland

    Holland Senior Member
    Messages: 605

    been noticing a drop in fuel economy? stock spyder injector setup is prone to breaking and leaking into the plenum. (engine would run better when cold and wide open since it needs more fuel at those times)
  11. chris694205

    chris694205 Senior Member
    Messages: 175

    I used AC delco plugs can't remember what the gap was. There is only about 60k on the motor so I'm hoping the fuel injector spider thing isn't bad. I have a buddy with a snap on scanner who can set the timing and its going in for an oil pan so ill have him check
  12. MikeRi24

    MikeRi24 Senior Member
    Messages: 563

    Check the EGR. Mine is a 454 Vortec, but same family of engines. It would run ok on initial cold startup, but as soon as it went into "closed loop" mode it would idle like crap, but full throttle it ran great. I messed around with almost everything and it ended up being a bad EGR valve, but in my researching I found a lot of info and in addition to what others have said you might want to check your throttle positions sensor, idle air control valve, air intake temp sensor, and fuel pressure regulator.
  13. 70monte

    70monte Senior Member
    Messages: 468

    I would also look at the cap and rotor. I had an aftermarket Accel cap with the brass contacts that corroded with about 25,000 miles on it causing the truck to barely run and have no power. I installed an AC-Delco set and the truck ran like new. I'm still running the same cap and rotor currently and this was about five years ago.