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TBI To TPI Swap???

Discussion in 'The Garage' started by George_Pimpdaddy, Aug 26, 2005.

  1. George_Pimpdaddy

    George_Pimpdaddy 1/2 ton status

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    I was working on my blazer when my next door neighbour came over to talk and was surprised when he said that he had a tpi system that i might be interested in. Turns out its from a 305 later 80s camero and its the full tpi system minus the harness but has 3 computers to work with. He recomends that it should be rebuilt though and offers it to me for $100 canadian.
    So i guess my question is will this work and fit onto my rebuilt 355 in my 89 blazer that already has TBI ??? Also how much would i really be looking at rebuilding it ??? can i do this myself to save on some $$$
    anyways i guess now i have to start to call around and see how much it would take to rebuild it and get a harness for it. :rolleyes:
     
    Last edited: Aug 26, 2005
  2. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    100 bucks to start is an amazing deal, I've got just over 1300 cnd into mine.

    However, keep in mind that the sensors and such can definitely add up. Find out what sensors the TPI has, and doesn't have, and go from there. As far as upgrading from a TBI, you're gonna be in pretty good shape that way! You can re-use much of the TBI wiring for the TPI, with a bunch of re-pinning of course. You'll also need to add some wiring for some things that the TPI has that the TBI doesn't, and remove some wiring for some stuff that the TBI has and TPI doesn't.

    My best advice to you is to make sure that the intake comes with all of the sensors, injectors etc, and that they all work, and if they do work, you may be in luck :)

    Also, do a bunch of reading up on the swap, there is tons of information out there, and make sure that you are up to the task.

    www.chevythunder.com is a great place to start.
     
  3. George_Pimpdaddy

    George_Pimpdaddy 1/2 ton status

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    has anyone here done this swap i know that ive seen it somewhere here. anyways can i just get new sensors for it like from napa or something like that or even the dealership? and would it jsut be easier to buy a new harness like a painless one? any good sites on info of the swap??? thanks again
     
  4. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    There is a tech write up on the swap here in the Tech Article forum but you have to be a paying subscriber to view it. I know that sometimes $25 can be tough to part with for a web membership but I assure you, it's worth every penny. :thumb:
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    I'm 99% sure there is an article on thirdgen.org on how to do the TBI to TPI swap. May even be a tech article.

    Truck stuff may be a bit different, but it's going to be a steep curve no matter which way you do it (well, short of aftermarket harness) but the wiring isn't tough, it just takes awhile to sit down and sort out what you are dealing with.
     
  6. George_Pimpdaddy

    George_Pimpdaddy 1/2 ton status

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    I was looking into one of those painless tpi wireing harnesses for my truck would that mean that i dont even need a computer device?? make it alot easier?
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Only thing easier is that you don't need to add/re-pin parts of the stock TBI harness. Other than that, you've got to pull the one thats in there and replace it.
     
  8. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    I'd definitely re-pin my TBI harness if I was in your position! Its really not that tough, and will save you a lot of money. Most of the wires that the TPI needs have already been run for the TBI. Only just a few would need to be added, or changed, and those that need to be removed can just be cut so they are no longer in view. Some TPI connectors are slightly different, but it is very easy to un-pin the TBI connectors, and swap them over to a TPI connector. Same with re-pinning the ECM for the `165 ECM if you are going MAF, just use a paper clip, and you can easily re-pin everything. Biggest thing to do is download an ECM pinout for both your current ECM, and the new ECM, and make sure that you keep track of all the wires. Some of the TBI wires will be different colors than the TPI wires, but if you make sure to lable every single wire with a peice of masking tape with their original designation written on them, then its very easy to keep track of them, and make sure that everything gets hooked up correctly.

    I did the TPI swap in my truck, and as far as the work goes, its been pretty easy, and thats starting with a truck that was originally carburated! The only issue has been getting nickled and dimed to death on little things that the setup has needed, and the amount of time it has taken me to rebuild my truck to a position that I could start it.

    I am now facing a pretty huge vac leak off my runner to intake connections, so make sure you don't make the same mistake as me, and put the gaskets on the ride side of the intake the first time around!

    If your engine is bone stock, you should be just fine running the stock TPI chip with the stock TBI engine, should mostly be a bolt the TPI on, re-route your fuel lines to the fuel rail, and do some electrical type swap.

    If you plan on modifying the engine at all, start off with a MAF system, then convert over to speed density once you have done all your modifications and have got the chip tuned as well as you want it, MAF is far more leniant with cams than a speed density setup. However, once you've got things figured out, do yourself a favour and swap over to speed density. You can then ditch the MAF, which is a bit of a bottle neck, and clean up your engine compartment by running a cone filter on the throttle body rather than having a bunch of ducting all over the place.

    If you plan to run the stock TBI engine, then start off with a stock speed density system as it is a bit more efficient, and is better programmed as it is newer than the old MAF systems.
     
  9. George_Pimpdaddy

    George_Pimpdaddy 1/2 ton status

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    Thanks for the help guys, just one more question how do i tell if its maf or speed density system im told its from a late 80's camero probaly 87. and can i rebuild the intake and runners myself or what kind of a shop could do the work for me?? thanks again
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    '85-89 are MAF, 90-92 MAP.

    '85 is essentially junk, everything was "one off" that year.
     
  11. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    However, if it is an 85 setup, it isn't very tough to upgrade to a 86 setup.

    MAF will typically have a cold start injector and a `165 ECM. Unless it is an 89 setup, then the MAF will not have a cold start injector.

    MAP / Speed Density usually will have the MAP sensor mounted at the back of the upper plenum, near the distributer and fuel pressure regulator. If you can post a pic of the setup, I can tell you a bit more about it.

    Finally, yes, you can easily rebuild the whole setup yourself. Just make sure that if you get it blasted, that you media blast it with walnut shells or something, sand will make a mess of that aluminum unless you know exactly what you are doing.
     

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