Announcement

Collapse
No announcement yet.

Hesitation/Runs Rough when warm and only a cruise speed

Collapse

Unconfigured Ad Widget

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Hesitation/Runs Rough when warm and only a cruise speed

    1990 K2500 5.7L TBI

    I appreciate any advice. My truck runs really rough and hesitates only after the engine has warmed up and only when I have slight pressure on the gas pedal. I don't notice any hesitation when accelerating. I don't really notice it at slower speeds either (but I'm not 100% sure if it isn't happening). But if I try and hold the speed at 55 mph, it hesitates and jerks, etc.

    Thanks!

  • #2
    Re: Hesitation/Runs Rough when warm and only a cruise speed

    Check the EGR system.... make sure its not drawing air. that could lean it out.
    WIP-1997 K2500 Ext Cab
    Volant CAI-BBK 85mm TB-Marine intake-32Lbs Injectors
    Patriot Vortec 185cc, Comp 1.6RR, 224/230-573/568 LSA113
    KB Pistons Thermal/Friction Coated, SCAT 383 Rotating, 6" Rods
    MSD Digital 6, HVCII Coil, 2200-2600 Stall, E-Fan, UD pulleys....


    http://prosilversystems.com

    Comment


    • #3
      Re: Hesitation/Runs Rough when warm and only a cruise speed

      Originally posted by Hicks-MofG View Post
      Check the EGR system.... make sure its not drawing air. that could lean it out.
      Thanks. I did check the egr valve. It seems to be working fine. I did unplug the vacuum line from the egr valve and it still has the hesitation problem. Any other thoughts on how to check out the egr system?

      Comment


      • #4
        Re: Hesitation/Runs Rough when warm and only a cruise speed

        does the check engine light come on and then goes off during the hesitation?
        O2 GMC RCSB 4.8L V8 AUTO 3.73's
        rebuilt/beefed up 4L60E(at 43,000miles)

        Comment


        • #5
          Re: Hesitation/Runs Rough when warm and only a cruise speed

          Thats the same thing mine is doing. NEUMANNZZ is a good resource, smart guy.

          My truck is a money pit with no bottom.
          1996 K1500 5.7 Vortec

          Comment


          • #6
            Re: Hesitation/Runs Rough when warm and only a cruise speed

            Originally posted by NEUMANNZZ View Post
            does the check engine light come on and then goes off during the hesitation?
            The check engine light does come on sometimes, but not right when the hesitations start. If I drive it for a long time, the check engine light comes on, but when I start it up again after shutting it off, it is gone.

            I don't know if it is related, but this truck idles extremely high when in park...
            Last edited by dosnotches; 11-10-2010, 06:25 PM.

            Comment


            • #7
              Re: Hesitation/Runs Rough when warm and only a cruise speed

              I do think it is EGR related now. I pulled the vacuum hose from the egr valve and plugged it up. I'm not getting any of the hesitations now...

              Originally posted by Hicks-MofG View Post
              Check the EGR system.... make sure its not drawing air. that could lean it out.

              Comment


              • #8
                Re: Hesitation/Runs Rough when warm and only a cruise speed

                replace the egr valve with an oem. not autozone crap.
                O2 GMC RCSB 4.8L V8 AUTO 3.73's
                rebuilt/beefed up 4L60E(at 43,000miles)

                Comment


                • #9
                  Re: Hesitation/Runs Rough when warm and only a cruise speed

                  Thanks. Do you think this is at all related to why it is idling so high? Or would you suspect another issue?

                  Originally posted by NEUMANNZZ View Post
                  replace the egr valve with an oem. not autozone crap.

                  Comment


                  • #10
                    Re: Hesitation/Runs Rough when warm and only a cruise speed

                    yes it could be related to high idle vacuum leak.
                    Last edited by NEUMANNZZ; 11-12-2010, 05:32 PM.
                    O2 GMC RCSB 4.8L V8 AUTO 3.73's
                    rebuilt/beefed up 4L60E(at 43,000miles)

                    Comment

                    Working...
                    X