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

[Dana Joe]

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...

[Pikey]

A link to his picture: http://www.gmtruckclub.com/forum/sho...E-5-7L-TBI-4x4

[Crawdaddy]

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.

[Dana Joe]

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!

[TRPLXL2]

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.

[Crawdaddy]

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.

[RayVoy]

They look like capacitors. Capacitors are used with relays to "capture" the back emf, turning the relay into a "slow release" relay. As @Crawdaddy suggested, perhaps to lengthen the pulse.

[Dana Joe]

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.

[tbplus10]

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.

[Dana Joe]

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!