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Thread: This is my first swap... Help

  1. #1
    Electronic Ignition!
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    This is my first swap... Help

    I'm putting a 91 350 tbi into my 94 vortec astro van. I need help with the engine wiring. What computer do I use and which wiring harness?
    ANY help would be great. Thanks

  2. #2
    Super Moderator dave w's Avatar
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    This link has wiring diagram information: http://www.gearhead-efi.com/Fuel-Inj...Information-0D

    If the old Astro Van engine is a 4.3 TBI engine, the conversion to a 91 350 TBI will be fairly straight forward nuts and bolts stuff. Basically you can use the Astro Van Harness (with very few modifications if the old engine is TBI) and Astro Van Computer (with a V8 Memcal and custom programmed PROM Chip). Most of the sensor connectors are the same for the 91 350 TBI engine and 94 4.3 TBI engine.

    dave w

  3. #3
    Electronic Ignition!
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    My 94 Astro had a 4.3 vortec in it. Totally different injection system.
    Last edited by meglaman; 07-18-2016 at 04:32 PM.

  4. #4
    Super Moderator dave w's Avatar
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    I'm thinking the 94 Astro has the 4.3 CPI system, with One Injector and 6 poppet valves?

    I'm thinking your harness can still be used, with some modifications. I'm thinking your harness will need two injector control wires, maybe re-pinned and maybe some sensors will need re-pinned also. The 1994 4.3 CPI system with automatic trans uses the same computer as the 1994 TBI system with automatic trans, except the computer Memcal is a different part #.

    There is also the option of using an aftermarket TBI wiring harness from Fuel Injection Connection: http://fuelinjectionconnection.com/gpage.html

    I think splicing and re-pinning wires in your harness would be a lower cost option?

    dave w

  5. #5
    Electronic Ignition!
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    Ya I checked into the premade harness and they are spendy.. So where should I start? I have my ECU and harness out.

    Thanks a lot for the info. I finally feel like I'm headed in the right direction.

  6. #6
    Super Moderator dave w's Avatar
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    I would start with the "Known" harness differences, like the TBI injector wiring. Then work through each sensor. Maybe you can re-purposed a wire, like re-purpose the EGR wiring to become an injector wire?

    dave w

  7. #7
    Electronic Ignition!
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    Is there a diagram or something showing what pin controls what?

  8. #8
    Super Moderator dave w's Avatar
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    Quote Originally Posted by meglaman View Post
    Is there a diagram or something showing what pin controls what?
    See Attached;

    dave w

  9. #9
    Fuel Injected!
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    When you delete the linear EGR valve from the 4.3 CPI, you will have a few wires that go through the harness connector to use for the 2nd injector wire. I did one of these swaps in a S10 Blazer years ago. Most of the CPI harness can be re-used and it is easily adaptable.

  10. #10
    Electronic Ignition!
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    OK. I have my harness and computer from my van laying here. If I use the wires from the linear EGR valve for a the 2nd injector, then when I reprogram the computer, I tell it what to use those pins for? Also. Will I need to add the ESC to my van wiring or is that handled somewhere else?
    I have changed a lot of engines in my day, but nothing this new ( I know I'm old) and this complicated of wiring. I really appreciate the help.
    Last edited by meglaman; 07-21-2016 at 11:48 PM.

  11. #11
    Fuel Injected!
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    Quote Originally Posted by meglaman View Post
    OK. I have my harness and computer from my van laying here. If I use the wires from the linear EGR valve for a the 2nd injector, then when I reprogram the computer, I tell it what to use those pins for? Also. Will I need to add the ESC to my van wiring or is that handled somewhere else?
    I have changed a lot of engines in my day, but nothing this new ( I know I'm old) and this complicated of wiring. I really appreciate the help.

    You will need the V8 knock sensor and V8 TBI memcal.

  12. #12
    Electronic Ignition!
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    I have the knock sensor that came with the v8. I also have the 1227747 computer that came with the engine. Will that have the memcal I need in it?

  13. #13
    Super Moderator dave w's Avatar
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    The knock sensor for the 1227747 is the wrong part / wrong part number for the 1994 Computer. Most likely you will need a Knock Sensor from a 1994 C1500 5.7 liter / 4L60E Automatic Transmission which should be BWD part number S8011 or SMP part number KS6.

    I've attached a couple pics of the Moates.net G1 memory adapter (Chip Adapter) I think you will ultimately need for a custom chip. The memcal is the blue / back part connect to the green G1 adapter.

    dave w
    Attached Images Attached Images

  14. #14
    Carb and Points!
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    Can anyone help me I have a 94 K1500 5 speed I am doing a v8 swap I have a 96 305 roller that I switched to tbi will an ecm work it's out of an auto I can't find a 5 speed ecm and it's ecm is for a 350 but should run cause it setup for a v8 I'm just know sure if my truck will start or if I'll be able too use my 4X4

  15. #15
    Super Moderator dave w's Avatar
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    I am wondering what the 94 K1500 original computer part number is?

    dave w

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