Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Adjusting TBI linkage

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by sharkman726, Mar 2, 2004.

  1. sharkman726

    sharkman726 Registered Member

    Joined:
    Apr 20, 2003
    Posts:
    22
    Likes Received:
    0
    Location:
    VA.
    OK I know this has been discussed many times before. In fact I think I asked about it a few months ago. My idle on my 90 K5 seems a bit high. I was advised you can adjust this by pushing a button on the linkage and pulling down on the cable to adjust. I can't seem to locate this so called button. Does anyone know if all of the TBI's have this option? I could be blind and not seeing it but any help would be greatly appreciated. /forums/images/graemlins/k5.gif
     
  2. heavy4x4

    heavy4x4 1/2 ton status

    Joined:
    Aug 28, 2002
    Posts:
    3,270
    Likes Received:
    0
    Location:
    Delafield, Wisconsin
    Idle speed for a TBI is set at the factory and controlled via computer.
    If your throttle cable is holding the TBI open a bit (hence a higher idle), you've got a problem (maybe something's hanging up somewhere - either in the cable housing or at the pedal).
    The process of "pushing in a tab and pulling on the cable" is similar to that of adjusting the TV cable. This is the "throttle valve" for the transmission and has nothing to do with the idle speed.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,982
    Likes Received:
    191
    Location:
    Roy WA
    As was mentioned, no real adjustment of the throttle linkage. (I had to bend the piece on my gas pedal where the cable mounts for additional throw, but thats because I went TPI)

    Of course, something could be bent, but you've got to figure out if the throttle is actually holding open, or if soemthing else is going on, and take it from there.

    I guess the easiest way to make sure the throttle is actually closing all the way is to take off the air cleaner and look, then disconnect the cable at the TBI, and make sure it won't close any more.
     
  4. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    The device you're describing is the Throttle Valve cable for a 700R4 automatic transmission.

    In addition to the things already mentioned, a vacuum leak can increase the idle speed on an EFI engine. Also make sure that there is no carbon build up just below the throttle blades.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,982
    Likes Received:
    191
    Location:
    Roy WA
    Harry's right in mentioning the other things.

    Bent/sticky throttle stuff is probably one of the least likely causes of high idle out there, (not that it doesn't happen, just not as common as things like vacuum leaks) I wouldn't bet my hopes on the throttle being opened, I didn't make that clear in my earlier post.
     
  6. sharkman726

    sharkman726 Registered Member

    Joined:
    Apr 20, 2003
    Posts:
    22
    Likes Received:
    0
    Location:
    VA.
    Thanks guy's. I was put under the impression you could adjust the TV cable (I should have mentioned that) I also should have mentioned I have a spacer. Thanks for the feedback. If you have any other suggestions I appreciate it.
     
  7. heavy4x4

    heavy4x4 1/2 ton status

    Joined:
    Aug 28, 2002
    Posts:
    3,270
    Likes Received:
    0
    Location:
    Delafield, Wisconsin
    [ QUOTE ]
    I was put under the impression you could adjust the TV cable

    [/ QUOTE ]
    Yes, you can...and in fact you should since you installed a TBI spacer...but, like I said, adjusting that alone doesn't do squat to your idle speed.

    [ QUOTE ]
    I also should have mentioned I have a spacer

    [/ QUOTE ]
    Yes, you should have. The reason why your idle is high is because you installed a TBI spacer, (and I'm assuming) without raising the throttle bracket. That bracket that holds the TV cable and throttle cable NEEDS to be raised with spacers in order to bring the idle back down. Right now, because you raised the TBI, the throttle cable is pulling on the linkage and your butterfly valves are open a bit.
     
  8. sharkman726

    sharkman726 Registered Member

    Joined:
    Apr 20, 2003
    Posts:
    22
    Likes Received:
    0
    Location:
    VA.
    Great. Do you know where I can get the spacers for this? /forums/images/graemlins/k5.gif
     
  9. heavy4x4

    heavy4x4 1/2 ton status

    Joined:
    Aug 28, 2002
    Posts:
    3,270
    Likes Received:
    0
    Location:
    Delafield, Wisconsin
    They should have come in the kit you bought. If they didn't, or you bought the spacer used, they are steel or aluminum (doesn't matter) 3/4" (I think...that or 1/2"...anyone remember) tall spacers that mount between the bracket and intake manifold. One of the bolts is actually the rear-most intake manifold bolt, so it's kind of a pain in the ass to get back there and put 'em in. Best thing to do would be to contact a company (TD Performance, etc) that sells them and see if they'll send you some spacers.
     

Share This Page