BIGFINDERMAN Posted December 7, 2019 Share Posted December 7, 2019 So I’ve been wanting to convert my tbi over to the mpfi. I’ve read everything I can possibly find on this subject. The usual talk is that it’s not worth the effort unless your going 3.3. But I have 3 4 door pathys in the back yard that all run. A 90, 94, and 95. All SE 4x4 autos. My 88 is a 5sp. My question is: Is it necessary to swap over the entire harness front to back? I know they disconnect in a few places but there a mess overall. I would hate to have to disconnect everything under the dash and everywhere else along the body. Is it possible without swapping the whole harness? Link to comment Share on other sites More sharing options...
BIGFINDERMAN Posted December 8, 2019 Author Share Posted December 8, 2019 It just seems to me that it would be easier to add in the additional wiring needed if I used the goods off a 90 model. There so similar minus the mpfi, electronic ac controls, and maybe a few other things. Couldn't you just re-pin the new ecu connector and add the extras needed? Link to comment Share on other sites More sharing options...
Slartibartfast Posted December 9, 2019 Share Posted December 9, 2019 I think you'd have more time into trying to hybridize harnesses than you would just swapping the lot, especially when you have a full running donor. A complete harness would also be easier to troubleshoot after the fact. The EL section of the service manual has the harness layout/pinouts/etc that should come in handy if you decide to make a science project of it. Do you have an FSM for '88? I've got an '89 PDF that should be close, let me know if you need info from that. I hear you on not wanting to take the dash out, I've got a whistle in my vents that's not gonna fix itself (hasn't so far, anyway) and I am not looking forward to taking the dash out for what will be the third time. Link to comment Share on other sites More sharing options...
BIGFINDERMAN Posted December 9, 2019 Author Share Posted December 9, 2019 Thanks for the info. I'll probably go ahead and yank the dash out and swap everything. I guess I should go ahead and swap out to the newer ac controls as well right? I need to get a fsm for a 90 auto model. There will be quite a few wires I don't need since I'll still be 5sp. Link to comment Share on other sites More sharing options...
Slartibartfast Posted December 9, 2019 Share Posted December 9, 2019 You can download the '90 manual here: Were the '80s HVAC heads different? Or does the donor have the push-and-pray climate control? Having had one with levers and now one with pushbuttons, I honestly prefer the levers for their simplicity. The pushbutton HVAC strikes me as an overengineered solution to a problem I didn't have. Link to comment Share on other sites More sharing options...
BIGFINDERMAN Posted December 10, 2019 Author Share Posted December 10, 2019 The 90 is push button. I'm not sure on the difference in head's. I'll check that out when I tear them apart. I'm with you. Can't go wrong with levers. I guess that's just more wiring I can stow away with the new harness. Thanks for the link! Link to comment Share on other sites More sharing options...
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