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TBI Swap...been searching, but...

Discussion in 'The Garage' started by TrcksR4ME, Aug 9, 2005.

  1. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    I have not found much info, and you cannot search ck5 because the search function requires words to be at least four letters, and TBI obviously is not.

    I aquired a pretty complete setup for doing the swap, but am wondering what things I can do without. I would like to ditch the EGR and I have heard the knock sensor is easily tricked by other engine and drivetrain noises. I also need to figure out how to wire up the computer.

    Any links or advice is appreciated.

    Oh, and since posts are worthless without pics ;) ...

    [​IMG]

    __________________
    '77 K5, Warn M8000, 402/350/203, 44/14bff, 4"/36" Irok's
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    If I hear another post about ditching the knock sensor, I want to see proof of why you would do this. Enough about that. (not aimed at you)

    Knock sensor is NOT easily fooled by engine noise, it responds to a specific frequency. You can't tell me that something that can tell the difference between a 305 and 350 simply by "noise" is something that will easily be tricked by other noises.

    Yes, they CAN react to things other than what they are designed for but without actually running one, how could you possibly know? You can't hear all damaging sounds coming from problematic combustion events anyways.. Every stock FI '87-91 C/K/R/V on here is running one.

    EGR: apparently TBI EGR (for trucks at least) is independant of the ECM, so removing it shouldn't throw a code.

    Easy fix for the VSS is the '81+ cluster, I've got the one I pulled that has the VSS stuff if you are interested. (not like they aren't easy to find of course)

    Wiring the ECM: you can cut a hole, or take the time to depin the ECM connectors, and open up the heater wiring grommet to pass them through. It takes just a few extra minutes (seriously) and is one less hole, plus it's chafe resistant. Depin the heater wiring to remove the grommet for mods.

    EVAP and AIR are removable as well, dunno if that will throw a code or not, suspect no on the truck.

    What year is the setup you have? (well, BCC will say which year too)

    Oh yeah, and whats the BCC on the PROM? Pull the access panel on the ECM and if there is a carrier, eject it with the side levers (like RAM in a computer) and pop the blue cover off. Under the blue cover, there should be a 4 letter code, like "APYP". Haven't dug into TBI stuff much, not sure if the carrier/PROM setup is the same as TPI or not. But pulling the access cover off to look won't hurt anything.

    I just checked out a TBI .bin (the "programming" for the PROM, what the engine runs off of, which is identifiable by the BCC sticker on the PROM) and there were conditions to enable AIR and EGR that you could turn off, as well as spark differences. If the .bin you have includes those conditions as well, you could potentially see some issues.

    Doubt the chips themselves I have would work in your setup, but any mods needed for your setup I've got the software/hardware to do it, short of maybe the chips.
     
    Last edited: Aug 9, 2005
  3. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    As far as the knock sensor goes, I think I will be running it. I was worried because of a chronic ticking I have had for awhile and unable to figure out. Upon pulling a few things apart today I discovered the timing belt is loose, likely causing my noise :D So I will go ahead with the knock sensor.

    You mentioned the VSS, and that was another thing I was unsure about. I read that it is used to control the tranny converter lockup (which I don't have), but what else does it do? If it is needed than I probably will need to get whatever I need to make that work.

    EGR, hope I can lose it just to keep the clutter down.

    I will look at the ECM and see what it is...what I do know is this all came out of 1990 454SS pickup truck. Its pretty complete except that he cut some wires that he said went into the dash area from the engine bay

    __________________
    '77 K5, Warn M8000, 402/350/203, 44/14bff, 4"/36" Irok's
     
  4. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    I've just recently done a tbi swap into my '78. If you have the money, my advice would be:
    Don't use the stock harness, get a Painless stand alone loom. (your life just became a whole lot easier).
    Get online to Turbo City and buy an inline tbi pump, VSS that attaches inline with your speedo cable. They also do fittings for the throttle body so that you can use rubber lines instead of trying to make the stock rigid lines work.
    I used a Jet adjustable FPR too.
    I'm using all sensors and EGR but no AIR.
    And if you don't have the late headers you'll need a weld on bung for the O2 sensor and ofcourse an O2 sensor!
    Oh...and as for photos! :D

    m swap 008 copy.JPG

    160505 021 copy.JPG
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    VSS is also involved when you are slowing down, raising your foot off the gas. Without VSS, when letting off the gas sometimes the engine will stall.

    Engine bay wiring that got cut was probably some of the emissions power feed (AIR, EVAP) and perhaps the fuel pump ignition source. You'll need to compare the wires with a wiring manual.

    Short of AIR and EVAP, not quite sure where an aftermarket harness saves you hassle, your TBI is probably about as standalone as most that vintage, (thus only a couple of cut wires you'll need to power appropriately) you need just as many wires to run the setup with either harness.

    If you are in the slightest interested in how these setups work, go download tunerproRT 4, the ECU definition for the ECM you are working with, (something like "1227747" on a sticker on the case) and the correct (or similar) .bin. For some reason, I find it interesting to look at that stuff. Something about being able to see what your timing looks like at various RPM's, etc. :)
     
  6. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    I hear what you're saying but I just meant from the point of view of not having the possability of broken (or soon to break) old brittle wires and the ease of everything being labelled and pigtailed...but maybe I just like it too easy!! :D
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    If it's a '90 from this area, short of a couple of connectors (knock sensor in particular worst potential) the wires should be in excellent shape. The '88 stuff I got from AZ is what is running my truck now, along with the '86 fuse panel I got from around here. Buy some new loom from any parts store for less than $1/foot, wiring looks as good as new.

    All the connectors are keyed/fit in one place only, unknowns will be the cut wires and any that potentially ran under the dash.

    Still need one or two injector power feeds, (TBI=??) ECM power, fuel pump ignition 12V source, 12V for VSS. (don't think I missed anything) All those should be fused seperately (at least IMO) to make troubleshooting easy, but other than that, wire labeling/researching is unnecessary. But definitely conducive to knowing where things are if anything ever fails.

    Is $350 really the cost of the painless harness?
     
  8. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    Lots of good info! It will take some time to figure this all out. I will have to get a book and some wiring diagrams for sure.

    I have been looking over the harness trying to figure out some of the plugs. On the inside of the cab, there are four plugs that come off the harness, and only the white plug has wires that go to the computer. The others the wires just go the firewall. Any ideas what these plugs are for? I am trying to figure out if these are all related to the tbi and computer or if there are some wires that piggyback the computer wiring harness :confused:

    [​IMG]


    On the other side of the firewall in the engine bay, the guy I got this from said he cut some wires that went into the cab on the drivers side of the truck. All of these go straight into the firewall back towards the computer. Would some of these be something like the VSS and tranny lockup?

    [​IMG]


    Not looking for any definative answers, just trying to get a general grasp of the wiring. All of the wires for the manifold sensors and TBI is intact, as well as the knock sensor. That accounts for the bulk of the wiring to run the TBI (doesn't it?) so what could all these extra wires be?
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    You don't have the ALDL connector anywhere, do you?

    Most of the cab wiring should be for that, just depends what the '90 had for diagnostic terminals. Cars had airbag test terminal in the ALDL, TCC test would be there, etc. along with all the standard stuff like data terminal, ground, and so on.

    VSS is probably one or two of the wires. VSS that ran without speedo cable used a twisted pair of wires from the tranny, speedo cable setups used one wire. I don't see them in the picture, all twisted pair I've seen are green and purple, with some sort of stripe on each of those wires.

    On cars there is a connector that somewhat resembles the clear one you post of, that's the one that all the ALDL wiring and ECM/injector power leads connect up to. Male/female connector of course.

    Going to want the 1990 C/K wiring manual, (exactly what you have of course) nothing more frustrating than trying to figure out wiring with the wrong colors illustrated. :)

    Just guessing on in-cab stuff not tied into the TBI, perhaps heater stuff?
     

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