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TBI to TPI conversion

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by antta99, Oct 20, 2004.

  1. antta99

    antta99 Registered Member

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    I can get a really good deal on a TPI setup off of an '88 Trans Am GTA with a 5.7l. I was wondering would it be a worth while swap on my '88 K5. I'll get everything, computer/harness/etc from top to bottom. Is this a realatively straight foward bolt on or no? Any recommendations/tips would be appreciated.
     
  2. Adub

    Adub 1/2 ton status

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    I considered doing it on an 89 K5 I had, but it looked pretty expensive. If you have all of the wiring and the computer, you are in better shape. I believe it does require some rewiring of the TPI harness to work in the truck. Check out www.thirdgen.org, they have all kinds of swap info.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Two ways to approach it from what I've seen on thirdgen.org. Change a few things on the TBI harness and run it like that, or keep as much of the TPI stuff as possible.

    Going from carb to TPI, I used all the TPI wiring, but that also involves adding in another fuse panel and a fair amount of wiring underdash.

    With TBI, I believe the correct fuses and what not are all present, so re-wiring TBI to TPI would be my first choice.

    It's a worthwhile swap, there are good gains to be had from TPI, but there are a lot of things to consider. Manual or AT donor and recipient? Speed input via VSS going to be correct? Get rid of cold start? Engine mods?

    Lots and lots beyond that, but all workable issues. 1988 is MAF, plumbing MAF costs more and is a bit more complex than a MAP TPI setup, (not nearly as clean an install) but it will handle more changes with less problems than MAP.

    Should be pretty straightforward bolt on, since the donor and recipient both use the same intake bolt pattern. I'd look to get rid of the TBI heads at the same time to be honest, but it's probably not a necessity.
     
  4. Kyle89K5

    Kyle89K5 1/2 ton status

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    You might also want to talk with these guys a little

    http://www.affordable-fuel-injection.com/

    They have been REAL helpful talking with me about putting TPI on the OFN Rig /forums/images/graemlins/grin.gif

    KP
     
  5. Hossbaby50

    Hossbaby50 3/4 ton status

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    If you know what you are doing then TPI isn't terribly hard to install. Especially if you already have TBI. There is about a 10% gain across the board or maybe a little more to be had by doing the swap.

    Do the research before you jump into the swap though. Don't just try and do it without doing the leg work first. It makes life very hard. Ask me how I know. /forums/images/graemlins/whistling.gif

    I love my TPI and it was TOTALLY worth the time and money to install it. I run an 88 MAF setup off a Firebird.

    I don't know how hard it is to convert a TBI harness to TPI but if you decide to swap harnesses then just get yourself a Painless harness and save yourself alot of grief and anger.

    Harley
     
  6. Ruthven13

    Ruthven13 1/2 ton status

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    As far as I can tell, it is a pretty straightforward job to convert harnesses. I did it on my K5, bus haven't finished it yet due to a motorcycle accident. I only needed to add wires for the manifold air temp sensor, which our TBIs do not have. Thirdgen.org has the diagrams for the repinning of the harness. Hopefully I will be done with mine soon so I will be able to tell you if it actually worked!
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    I hope for the best for you, but I wouldn't expect everything to work perfect right off the bat. /forums/images/graemlins/tongue.gif

    Taking your time installing it though will pay dividends when it comes to firing it. Can't wait to hear how you like it when you get it running!
     
  8. antta99

    antta99 Registered Member

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    I didnt realize '88 GTAs were maf, but I wont let that stop me. I was gonna go with a Howell, or a Painless harness anyway. I'm trying to go for a plug and play deal. Or at least as close as you can get. I was already thinking about upgrading the heads and putting a torque based cam in with shortie headers. This will be a summer project after it stops snowing. Thanks for the input.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    I say screw the aftermarket harness. If you TBI one is good, why spend good money on something you already have?

    Not to mention, doing your own wiring will make SURE you know what is what, and where each wire goes. Believe me, if you don't know what does what, and how it does it, and you have a problem, you will be scratching your head.

    If it's going to be a long project, you can spend the time learning the wiring. If you do the swap, the service manual for that year vehicle is a must IMO. If you don't have the service manual and electrical manual, again, you will be scratching your head a LOT. The service manuals flow charts for troubleshooting are worth their weight in gold.
     
  10. Kyle89K5

    Kyle89K5 1/2 ton status

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    AFI (see link above) Is workingon a tie in harness for the TBI equipped rigs. This you will just splice in to your harness, swap chips and run.

    This is for their TPI systems, so I don't know if they will be offering it for a retrofit system, but it's worth a call. I'd rather plug and play than spend a day going over schematics making sure my wiring is square.

    If you call them, tell them Kyle from the OFN sent ya /forums/images/graemlins/wink.gif

    KP
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    You may want plug and play now, if you can't trust your abilities, perhaps you shouldn't be doing the swap? If you meant the plug and play add-on harness, nevermind. /forums/images/graemlins/smile.gif

    I know that comes off harsh, I don't mean it that way, but plug and play=I have no idea how to fix or troubleshoot it if something goes wrong. If it's just a tie-in harness though, you will have to "install" it, which will certainly give you an idea of whats what.
     
  12. Kyle89K5

    Kyle89K5 1/2 ton status

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    [ QUOTE ]
    You may want plug and play now, if you can't trust your abilities, perhaps you shouldn't be doing the swap? If you meant the plug and play add-on harness, nevermind. /forums/images/graemlins/smile.gif

    I know that comes off harsh, I don't mean it that way, but plug and play=I have no idea how to fix or troubleshoot it if something goes wrong. If it's just a tie-in harness though, you will have to "install" it, which will certainly give you an idea of whats what.

    [/ QUOTE ]

    Who are you to tell me whether or not to do a swap Dorian? Holy hell man, what about the guys that don't know how to setup their own gears swapping axles? I guess I should learn how to rebuild my 400 tranny before it goes in? Harsh or not, that's a bullshit statement aimed at showing how smart you consider yourself to be as opposed to someone else. Was that harsh? Maybe, but telling people not to swap if they don't know all the fine points is crap. Plug and play harness's are there to take the guess work out of doing it.

    BTW, the harness I'm refering to is a piggyback "tie-in" harness, but they have complete retro-fit kits for non EFI vehicles that ARE plug and play.

    Maybe I come off harsh, but I'm sick and tired of people telling me that I shouldn't do something because I don't know how, or won't know how to fix it. How the hell do we learn? Trial and error, trouble shoot, road-side fix. I'm not going to learn how to build a new car before I buy one. I'll learn as I go.

    KP
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    Who are you to tell me whether or not to do a swap Dorian?

    [/ QUOTE ]

    Somebody thats done the swap, had problems himself, and has been on this board and many others long enough to see what happens when people do swaps and have no idea how something works. You wouldn't put a doubler in a truck then expect someone off the street to know how to use with no instruction would you?

    [ QUOTE ]
    Holy hell man, what about the guys that don't know how to setup their own gears swapping axles? I guess I should learn how to rebuild my 400 tranny before it goes in?

    [/ QUOTE ]

    I love it when people blow crap out of proportion like this. How many people need to setup gears on the trail? How many people rebuild 400's in Moab when theirs fail? Yeah, thats right, probably NONE. How many people get stranded on the road and need to know what the fuel pump relay is, or where the oil pressure switch is? Yes, thats right, many more than setup gears on the trail.

    [ QUOTE ]
    Harsh or not, that's a bullshit statement aimed at showing how smart you consider yourself to be as opposed to someone else.

    [/ QUOTE ]

    Actually, it sounds like you are intimidated that someone thinks you should know how certain things work instead of just slapping them on there and hoping everything works fine for years. Hey, thats my opinion, if you feel like less of a man because of MY OPINION, then ignore it. Why do you think people STILL rip off EFI and put a carb in place? Because they don't have the time, motivation, money, or patience to make the EFI work.

    [ QUOTE ]
    How the hell do we learn? Trial and error, trouble shoot, road-side fix.

    [/ QUOTE ]

    Whats that saying? Smart men learn from their mistakes, truly wise men learn from the mistakes of others.

    Perhaps you like the idea of learning how your EFI system works at 10pm on a snowy trail outside of cell phone range by yourself, and if you want others to follow you down that path, go ahead. Parts stores also like people that do swaps without knowledge, because they are the type to throw $500 in parts at a problem that could have been deduced from knowledge of the system and the factory service manual.

    My previous post was pretty short, but go ahead and show me where I told people not to swap things? Are you telling me that someone that has no clue how to bleed brakes should just trial and error it? Come on man, get real. The information is out there, if you want to ignore it, fine, trial and error it.

    I do like the way you contradict yourself though. You encourage plug and play, yet "I'll learn as I go". Once again, back to my WHOLE point that you blew out of proportion, plug and play isn't learning.
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Oh, and before I forget:

    [ QUOTE ]
    Plug and play harness's are there to take the guess work out of doing it.

    [/ QUOTE ]

    There is guess work if you don't know what the hell you are doing. What kind of guess work is there if you use the manual and understand what things do? If you can't do something without guessing, MY OPINION is that you probably shouldn't be trying it until you do some more research.
     
  15. Kyle89K5

    Kyle89K5 1/2 ton status

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    You know what Dorian, I typed a 1/2 dozen replys to this, but I'm not going to bother.

    You stepped in and judged my ability to swap, simply by my CHOICE of doing a plug and play harness as opposed to your method. You continue to question my ability, and that's fine. I'll not get worked up becuase of it. I offered a different solution for folks to take a look at. Mentioned how I'm going to do mine. You didn't like it and offered your feelings. So be it.

    You're a smart enough guy D, I know that. I've known that for years on this board. You've helped me in the past, and I've taken your advice and used it, WITH SUCCESS. I appreciate that. I hope you can see my side of this, and understand what set ME off. I learn as I go. That's my method. Is it wrong? By your standard yes. All my life that is how I've done things. Trial and error. It's my genetic makeup. Do I want to learn? SURE! Why the hell do you think I started the OFN? To LEARN how to fabricate. I also practice in the shop. I'll talk with folks, try a new welding method, then talk some more with folks, then try some more, etc etc etc...

    I'm not going to continue this argument. It's pointless. I have my feelings, you have yours. If you were my neighbor I'd still invite you over for some chow if you wanted (and ask how to swap my TPI on /forums/images/graemlins/wink.gif )

    My plug and play take on things:

    Have you ever wanted something done, and felt that maybe you should know how it works, or even have an idea of how it works, but would just rather pay to get it done? I've got a good understanding of electricity in my house. I'm pretty sure I could do it, and I'm learning more about electricity every time I do, but there are times when I would rather let an electrican wire the new 220 circuit to the shop. :shrug: I guess I see things different on things. Lot's of stuff I'll do myself, lots of stuff I'll let people who know what they're doing do it.

    That's my take on PnP, for what it's worth...
     
  16. Hossbaby50

    Hossbaby50 3/4 ton status

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    I have to agree with Dorian on most everything he said. If you want a plug and play harness for the ease and cleanness of install then that is fine, but you NEED to know how this thing works. If your not willing to take the time to learn how it works don't do the swap. It is not a "plug and play" swap. Trust me I know.

    I am one of the people who thought I would learn as I went and didn't do my homework and research on the swap before I started. It was a PITA because I tired to dive into the swap, and I do have the plug and play harness.

    The plug and plays are 100% plug and play. There is stuff you have to hook up, wire around, etc. The Painless directions are pretty good but nothing is 100% accurate when you are doing a custom install.

    TPI is bad ass when it runs right but when it is not it is a HUGE pain in the ass, even if you know what you are doing. If you don't have any idea then you will be totally lost and SOL. I carry both the Painless wiring harness manual and also a Trouble shooting guide in my truck at all times because you never know when or where the TPI will go out on you or what parts you will need to diagnose the problem and fix it.

    I have had my TPI system in for almost a year and I still am trying to figure everything out. I did learn a lot in the initial swap but I still learn new things all the time.

    One of the worst feelings in life is being in the middle of nowhere and seeing that little yellow light kick on and the truck running like [censored], assuming it will run at all. And I carry the parts to get it to run and it still sucks a big one.

    If you are not willing to learn about the system when you swap it don't swap it. If you are willing to learn then do the swap but dont expect it to be a cake walk even with the plug and play harness if you don't do the homework on it. I made that mistake already.

    Harley
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    You stepped in and judged my ability to swap, simply by my CHOICE of doing a plug and play harness as opposed to your method. You continue to question my ability, and that's fine.

    [/ QUOTE ]

    I didn't intend to judge your abilities. You can't judge someones abilities before they attempt to do something, right? If it makes sense to word it differently, I believe that learning more about something (in this case EFI) before jumping in is a good idea, if not mandatory.

    My "method" as you call it involves learning. I don't really see how anyone can deride learning, not that you necessarily are, just that it is being assumed I am saying 100% the only way in this case is to use the stock harness. I could care less if someone decides to go with a Painless harness (or whatever) as long as they have done the research to see what they are getting themselves into, as with any swap.

    It all comes down to an informed choice, opinions from any angle help people make up their own mind.

    I know full well if we were discussing this face to face, it would be a much friendlier conversation the whole way through. Internet provides a very easy way to misinterpret peoples mood and intentions.

    There are more things anymore that I will gladly pay people to do, but working on vehicles isn't one of them. That is one (of many) areas that I personally believe there is NO ONE more qualified to work on your vehicle more than yourself. Sure, most of us can't fabricate large parts, or have the tools to build a roll cage, but the simple fact is, in my opinion, no one gives a darn about how your vehicle runs or looks like you do.

    I know probably one person besides myself I would trust to work on my vehicles, and understand how I would want things. When I look at some of the aftermarket harnesses, or chip burners (and this is only for one component swap!) I see it plain as day that many of these people/businesses are not concerned with doing things "my way", or concerned with much more than "good enough". It may work fine (and some harnesses are pretty good) but if it isn't done the way I want it, I couldn't be happy with it.

    If I had to get my rig running from carb to EFI in one weekend, I guess I'd consider a plug and play harness. But I'd never put myself in that sort of situation, because thats the way I am.

    After doing this swap, I can say that the learning curve is STEEP on these setups if you choose to delve into them. However, the rewards of knowing how the system worked paid big dividends for me later on. I had the "luxury" of taking my sweet time though, and I didn't have a TBI harness to start with.

    I do like the idea of the add-on harness for the TBI to TPI conversion though. It should be pretty simple, so hard to mess up on their part, and an easy addition to what exists, hopefully for a very minimal cost. I assume doing the TBI to TPI re-wiring yourself requires running a few more wires, if the add-on wiring is done right, there is no reason not to run it. Saving the hassle of cutting, splicing and connecting the new wires has to be worth a few hours worth of work, no matter how simple the TBI to TPI re-wiring is.

    Seriously, if anyone has done a similar swap using the stock wiring (whether carb to EFI of TBI to TPI, etc) it would be nice to hear from them whether they thought it was worthwhile to learn what they did by doing everything themselves.

    Maybe there are people that feel differently than I do about it, but I just don't think you will find people who will complain...I think you'll hear that even though it was hard, it was still worth it.
     
  18. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

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    I don't mean to hop in on the tail end of a already hot discussion guys, but I really think that there are two sides to this discussion. I've built from scratch an entire TBI harness, and reduced another down to bare minumums so that it could be installed onto any car with just 12v+, 12v switched, and a ground.

    Coming from some folks perspective, (those who don't have the time, capacity or otherwise) maybe just buying the piggy back setup is just simpler, quicker and stupid proof. It would be ideal for a company that was say, doing lots of conversions for paying customers. Granted that it will most likely bite said buyer in the ass one day on the trail when ONE wire pops loose somewhere... but SO WHAT! Its just entrepreneurial spirit at its best. Build it, and they will come, right?

    I personally agree with everything thats been said thus far. There are pros and cons to each side of the story. But not everyone has the time to go though and re-design a factory TBI harness to support a TPI setup.

    Just my $.02 if anyone cares.

    -Dan
     
  19. Kyle89K5

    Kyle89K5 1/2 ton status

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    [ QUOTE ]
    My "method" as you call it involves learning. I don't really see how anyone can deride learning, not that you necessarily are, just that it is being assumed I am saying 100% the only way in this case is to use the stock harness. I could care less if someone decides to go with a Painless harness (or whatever) as long as they have done the research to see what they are getting themselves into, as with any swap

    [/ QUOTE ]

    My method is also learning. I just spread my learning out over the course of the swap. Learn as I go, maybe that's the way to describe it.

    I also wasn't bashing your choice to use a factory harness, far from. I too could give a crap about what harness to use. My response was to offer up another area of expertise in TPI swaps into these vehicles. Not discounting your advice.

    AFI is developing the harness to use the existing computer to power their TPI setup. This is, IMO as close to plug and play as you'll get for TPI.

    Their existing plans are to take their systems and turn them into an Edlebrock or Holley competitor. Those systems are plug and play, the same thing they are looking to do with TPI.

    ***STANDARD ISSUE DISCLAIMER***

    Anyone that truely belives plug and play means that, or is reading my posts as an afternoon swap, I apologize for the misconception. Plug and play by my def. means that you don't have to sort 2 factory wire harness's to start tying things together. Instead, a provided harnes TIE'S-IN to the existing harness and allows less down time of sorting. More of a Tab A into slot B kind of deal. There is still work, and there is still time spent tuning, espceciall if you have done any work to the engine that would throw a "factory" setting off. That is, what I've found, to be the single biggest issue with TBI/TPI swaps, and the point where the money throwing starts.



    Actually, Dorian, I'll be honest, my first reply wouldn't have been friendly face to face either. /forums/images/graemlins/blush.gif Sorry. I tend to do the West Texas police approach on some things. You know, ***BANG***____________________________________________freeze...

    I apologize for that. I also agree on working on your own rig and knowing how to keep it running etc. I tried that with my 700R, I also decided that even with all my research, tools, and planning, I needed an expert, and in the end, I'm happy I did :shrug: I found my limit and a 700R seemed to be it. Plenty of other things don't bug me, that one on the other hand, well, did and still does /forums/images/graemlins/frown.gif

    To each his own. By the way, can I have your phone # so that when it's 10pm on a snowy night and I'm stranded I can call?

    Thanks

    KP
     
  20. Kyle89K5

    Kyle89K5 1/2 ton status

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    [ QUOTE ]

    Just my $.02 if anyone cares.

    -Dan

    [/ QUOTE ]

    We don't care Dan, sorry...





































    /forums/images/graemlins/grin.gif

    This discussin isn't hot. You've seen me fly off the handle, actually, I did it at you once /forums/images/graemlins/wink.gif I just got a little worked up and didn't think through my response like I shouldd have.


    KP
     

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