Will a '90 (map) engine/harness/computer work in an '89 (MAF) car? - Third Generation F-Body Message Boards

Douchermann · 10-01-2007, 09:58 PM

Hey guys. My question is, will my car run just as well as before if I swap the engine, engine wire harness, and computer from a 1990 formula into a 1989 trans-am. The thing that worries me is the change in '90 from MAF sensor to MAP sensor. I just pulled the motor out of the '90 car as well as the harness, and I already noticed a possible problem. The power brake pressure sensor is in the chassis wiring harness of the '89 car, but it's in the engine management harness in the '90 car.
What should I do about this, and what other problems might I run into? The quicker the response, the better.

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Kevin91Z · 10-02-2007, 02:26 AM

Click here and read how this gentleman swapped his '89 setup to a 90+ setup:

http://www.eecis.udel.edu/~davis/z28/

Douchermann · 10-03-2007, 05:06 PM

But see, I already knew you could make a MAP engine run off MAF wiring. My question is, is there a difference between the entire wiring harness. I have no need to repin the 89's harness, due to the fact that I already have a 730ECM harness. My question is will the 730ECM harness and computer work in a previously 165ECM powered car? If it doesn't, fine, I'll fix it. The reason I want to know is so that if the car doesn't start when I turn the key, I can narrow it down to either I forgot something, or the wire harness just doesn't work, instead of "it could be anything". Thanks for the link anyways though.

Kevin91Z · 10-04-2007, 01:34 AM

You will run into a problem with the bulkhead connector on the firewall of the driver's side. The harness may or may not match up.

1bad91Z · 10-04-2007, 02:25 AM

I've done a few Speed Density swaps for people. The only thing that sucks about the swap is if you use a SD harness in a 85-89 car, you will lose the windshield wiper wiring. The wiper wiring is integrated into the 85-89 TPI engine harness. The 90-92 SD harness does not have this wiring integrated into the engine harness, it's integrated into the body harness that plugs into the firewall onto the side of the big bulk head of the engine harness (where it plugs into the firewall).

Hope this helps!

Dyno Don · 10-04-2007, 11:39 AM

What he said^

You are better off to repin the '89 harness.

Douchermann · 10-04-2007, 03:13 PM

Yeah, I've thought about that road, but the owner, or owner before him, hacked up the wiring harness. There are splices here and there, and wires cut, wires taped. For some reason, the 2 electrical fan connectors were cut into one.

As for the two harnesses, I also noticed the VSS connector is on a different pin on the cabin connector that comes with the ECM connectors, but I just have to move it over. I would take your guys advice if the 89 harness was whole and unadulterated. I looked at the pinouts though and there isn't too much different, so I shouldn't have *too much* of a problem switching it around a little bit. Thanks for the help everyone.

Morit · 01-03-2009, 06:34 PM

Have you done it..? Anything more specific that you encounter..?

Douchermann · 07-19-2009, 12:00 PM

Yes I have. Everything works on the car right now except for the speedometer. Thats only because I don't have a reprogrammer for the 730. The windsheild wipers weren't a problem on the C100. PB blaster will dissolve the water proof tar all over the connector, and a tiny screw driver can be used to help get the pins out. For the wiper system, I cut the wiper wire harness off, with about 6 inches leading into the connector of the 89 harness. Then, I used a screw driver to pop the remaining 6inches out. I followed the same pattern into the '90 harness and popped all the 6" lengths of wire into that, then just soldered the wiper harness on that. For the power brake sensor, I just moved it over to it's correct spot.

IIRC, everything else was correctly placed, car fired up on first try. Obviously you have to repin the other connectors as well, but that's not too much of a problem, there are diagrams and pinout documents for that. I can't remember everything though, given this was two summers ago. The car is still running however, so I'm pleased.

Morit · 07-19-2009, 02:02 PM

I have everything working except the speedometer..
Dont know what to do, my 88 used buffer box, and '730 have it build inside..
Dont know what to connect with what..
Any ideas?

Douchermann · 07-26-2009, 02:15 PM

Check the pinout diagrams. The pin on BC6 is the speed output signal you want. This wire should connect with the wire that A10 went into on the original computer. You then need to reprogram the computer as stated on the right column of this page:

http://www.eecis.udel.edu/~davis/z28/ECMs/86to92.txt

Morit · 07-26-2009, 06:31 PM

I dont get it :P
I am using 91 harnes with 91 engine, so connecting it to computer is no problem.
I have dash harness from 88 and everything works fine too... (except speedo

)
The problem is that my 88 body had buffer box, and 91 dont.. I know the wire that goes out from 730 computer and should go to the speedo, but dont know where to connect it and what to do with the buffer box..