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  1. rescuekrawler

    rescuekrawler Registered Member

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    What do I need to know in doing this swap from tbi to tpi Who has the best harness where is best to get the tpi (junk yard or rebuilt etc.) What are some good site to look at in doing this. And feel free to add anything that I will need to know in doing this.

    Thanx
    Tom
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    Thirdgen.org has alot of info on fuel injection. You need to do ALLLLLLLLLLLL your homework before diving into a TPI swap, trust me I know, I did it without knowing everything I needed to know and it took awhile.

    I like Painless Wiring for the harness.

    Read ALLLLL you can about the swap.

    Ryan B did a writeup on the swap that is in the Bloody knuckle I believe. Going from TBI to TPI should be easier then carb to TPI like I did.

    You will need to swap a TPI fuel pump in your tank and remove the old TBI pump. You will need to move your fuel lines at your motor around and lengthen them to reach where they need to connect to the TPI runners. You may need to convert the Saginaw fittings on the runners to AN to help ease the extention and movement of the fuel lines. You will probably need to add in a high pressure rated fuel filter inline with the pump somewhere. Any soft fuel line will need to be replaced with high PSI rated soft fuel line.

    Then you need to swap the manifolds and harnesses. The harness is very easy to install. It is almost plug and play. There is a few connections you will need. You may need a new knock sensor in the block but I am not 100% on that.

    There is obviously more but I am not sure what. If you plan to keep AC then you need to look into that. I deleted my AC to make my swap easier.

    You also need to figure out if you want to run MAF or MAP TPI. I run MAF and I like it. It leave your options more open on adding hop up parts to the motor if you desire. MAP is also good to.

    You need a complete TPI system off a 350 TPI car from 87+. You need the manifold, runners, injectors, sensors, ECM, throttle body, all the bolts, the oil pressure sensor, knock sensor, relays, etc. If you plan on using an aftermarket harness you don't need the harness. I would just buy a new fuel pump instead of trying to pull the old one out of the car.

    Harley
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    tbi can be rewired for tpi, I would read up on that process, lots of info on thirdgen.org.

    MAF is ok, but the MAF itself is very costly compared to MAP if you have to replace it. MAP is not as "adaptive" to engine mods as MAP, but if you end up with '89+ TPI(think thats right) you will have to deal with the VATS issue in the ECM. Then you start getting into custom PROM burning, etc., which also isn't bad. TPI can really be tuned to "perfection", burning your own chips is the only way to do it though. Don't HAVE to, I'm running an '87 305 ECM with my setup right now, until the chip burning stuff shows up, but it doesn't run as well as it can.

    Stay away from '85 TPI at all costs, especially since the intake bolt pattern will be wrong for you.

    There is a lot to the swap, but since you are already TBI, I *personally* would run the stock harness, especially if you know it works now. No matter how you slice it, there is going to be a huge learning curve, and there should be. Once you understand what does what and goes where, you won't be so intimidated.

    Check out thirdgen.org's classifieds for setups. I got mine for about $500, but I'm not sure if the guy is still selling them or not. Complete take-offs from cars.

    Get a service AND wiring manual for the year injection setup you end up with, and you'll need one for the truck too, at least I did. Maybe not if the tbi->tpi re-pin of the harness is straightforward, but I needed to know how the stock truck fuse panel was wired for my '86.

    If anyone tells you you don't need the manual(s), they are moronic. You can spend 100's of dollars throwing money at injection parts in a heartbeat, where a manual's troubleshooting flowcharts will save you a ton of time and money in the long run alone. Besides the fact, once you have a manual, you will spend hours reading it, as they are that informative, and make so much sense.
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Try looking at Street & Perfromance in Mena, Arkansas, here is a link to their website http://www.hotrodlane.cc/. These people make a piggyback harness to go from TBI to TPI. I have personally bought a wire harness from them for a TPI conversion i did a few years ago and it was a Great looking harness. There is no comparision to a painless wiring harness. You need to talk to Mark, he is the owner and has a wealth of info to give you even if you don't end up buying from him. :thumb:

    I just went to the website and found the integrator harness on page 48 so you don't have to search around for it. The harness isn't cheap by any means at $545.00 and an extra $89.95 for automatic trans, but it is plug and play and very quality stuff.
     
  5. rescuekrawler

    rescuekrawler Registered Member

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    Thanx guys I have aldreay decide to go with street and perfomance fornd them before you posted and running their Intergarted harness
     
    Last edited: Jan 3, 2005
  6. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Cool, once you get that thing installed using their harness i would like to know how easy it actually was. I am soon going to do the same thing and buying my harness from S&P as well. :thumb:
     
  7. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Yah i went with the street and performance harness.. I took 4X4HIGH's advice on that one.. and actually started looking at the car shows and asking the guys which harnesses they were running.. You could tell the bare wire ones with zipties were the painless harness. Street and performance wiring harnesses come with factory type shrink tube covering all the wires.. When installing the harness and feeding all the connectors and wires carefully through the new 1 1/2" hole in the firewall, you'll be glad you have the extra insulation.. Not to mention the long term results with it.. I wanted to do it once the right way and be done with it.
    I think some of the guys on here have shaved a couple hundred bucks and bought a roll of tape to insulate their painless harness, but it won't be as nice of a job.
    Here is the link to the write up of my TPI install: http://coloradok5.com/forums/showthread.php?t=106209


    OH, By the way Scott... The Auto tranny conector 4 prong deal comes on the $545 harness.. I didn't pay any extra and it came with the wiring that goes back to the tranny with a 4 prong connector. I didn't use this connector with my TH350.
     

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