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I Bought a '95 TBI 5.7L with "resistors" stubbed into the injector power leads...WTH?

Discussion in 'GM Electrical Tech' started by Dana Joe, Jan 25, 2013.

  1. Dana Joe

    Dana Joe New Member

    Greetings -

    As stated in the title, I bought my '95 Suburban with what looks to be resistors (fusible links?) wired into each injector. I'll try to get a photo posted as soon as possible, to show exactly what I am describing. In the meantime, has anyone ever heard of such a thing? If so, why? I've been stumped for a while now. The truck has a 'stumble' @ idle, under forward / reverse gear mode while at a stop...could these be reason for the 'stumble'? I've posted a picture in my 'Garage' area, under the 'Under the hood' category. Any ideas? Crazy I tell ya...
    Last edited: Jan 25, 2013
  2. Pikey

    Pikey Moderator Staff Member 2 Years ROTM Winner 1000 Posts

  3. Crawdaddy

    Crawdaddy Thread Killer Extraordinaire Staff Member 5+ Years 1000 Posts Platinum Contributor

    That's obviously not factory. Why it was put there, I have no idea. It looks like it might actually be a capacitor. Perhaps the previous owner put them there to lengthen the injector pulse as a power adder. Does it work? I dunno. Those injectors use a peak and hold strategy to operate.
  4. Dana Joe

    Dana Joe New Member

    Other than the 'stumble' I described, yeah...they work fine.

    Then again, could this be a cause for the 'stumble' I am experiencing?

    Thanks for your reply!
  5. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts Platinum Contributor

    I was pretty confident I knew what you were talking about, and then I saw the picture and I went WTH??? GM does use "heat sinks" on a lot of there engine harnesses, but they look nothing like that. I would agree that it is something aftermarket.
  6. Crawdaddy

    Crawdaddy Thread Killer Extraordinaire Staff Member 5+ Years 1000 Posts Platinum Contributor

    If you can get a closer picture of one of those blue components, whatever they are, I can try to tell you more about why they may be there. I can't read the number in your existing picture.
  7. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    They look like capacitors. Capacitors are used with relays to "capture" the back emf, turning the relay into a "slow release" relay. As [MENTION=14098]Crawdaddy[/MENTION] suggested, perhaps to lengthen the pulse.
  8. Dana Joe

    Dana Joe New Member

    Thanks guys - I will try to get a better photo tomorrow. If the numbers that are printed on these "devices" aren't legible in the photos, I'll be sure to include them in the text of my next post.
  9. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Those are capacitors, I don't remember the name of the company, heck I don't even think their in business anymore either.
    Those are part of a performance kit that supposedly boosted performance and mileage, the idea was to pulse the output of the injectors, instead of a straight shot of fuel these capacitors would shoot, pause, shoot allowing time for first shot of fuel to vaporize before shooting the second shot in. I Don't think the idea caught on or really did very much for performance.
    The kit also had a piggyback chip that plugged in on the ECM, they could run without the ECM chip though, not sure what it's purpose was.
    Those capacitors came in two or three modes, I know one mode was a two shot pulse, another mode was a three shot pulse, and i believe the third mode was an extra long pulse that kept the injector open longer than the factory time frame.
  10. Dana Joe

    Dana Joe New Member

    Thanks, Tim! I haven't checked to see if there is any kind of chip installed in the vehicle; would I be able to tell anyway? None the less, with the timing reset to factory spec's, I've noticed my mileage go up, but also a drop in off-the-line power. I recently had the distributor assembly replaced at a buddy's shop - unbeknownst to me, the dizzy was let loose, so upon a recent troubleshooting check of the cap and rotor, I unknowingly advanced the timing. I loved the acceleration, but my gas mileage, as you can imagine, dropped.

    All things stated here, might this TBI mod be reason for the 'stumble' I'm experiencing? Am I safe to assume a guy could remove these "capacitors" and re-wire the injectors just as easy as it looks?

    Again, thank you all for your help...it is most appreciated!

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