I have an 87 maf tpi setup. I want to convert to speed density. I plan on probably just buying a gm speed density harness. My problem with this is that I need to know what all is different about the chassis harness and if I can just change it to work or if I need one from a tbi car. I know that my spedometer wiring will be different. I have been told that you just dont use the buffer. I would like more information on how to get rid of it. Also I think that I may have read that the aldl connector would be wired different. If any of you know what I need to do to fix any of these problems or know of any other that I will have to deal with pleas help me out.

Thanks

Ben

 

please use other topic, I accidentally posted it twice.

Thanks

Ben

 

I did a tbi to tpi speed density swap. I just repinned the tbi harness to the 7730 ecm plugs, wired in the injectors, soldered all splices, and saved the $600 gm wants for the sd harness. You would have to add a map sensor to your wiring. Painless wiring makes the speed sensor/buffer you need for the speed density system. It is part number 60116(4 pulse) and can be ordered from any autozone. Just give them the part number to type into the computer and it will come up. By a $3 pin removal tool and just note where each pin will go. Go to the local boneyard and buy a 7730 ecm and cut about 6 inches of the harness with it. This will give you some pinned ends to pigtail the vss wires and map sensor wires. The aldl on my tbi was the same, no re pinning. Try this before spending $600 on the sd harness. You should need the ecm, the chip, a map sensor(snag one from a tbi car) and the vss. You could go without the vss, but for $50, you might just want to hook it up, that way all inputs are there. Good luck to you.

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89'Camaro Convertible,96'firebird wheels,79'Z28 hood scoop,soon to be a 350 tuned port injection engine, 3.27 posi disc brake rearend,36mm front sway bar, 24mm rear bar, all donated by a 89'Formula 350, Poly sway bar bushings and end links, Dark yellow green paint from Bonnevilles, tan www. mrmikes.com leather interior,Macewen white face gauges.
Dreaming of a RamJet 350,
Jet fan switch
180 degree thermostat
Flowmaster cat back system
2nd place is always the first loser!

[This message has been edited by 89rsvert (edited November 14, 2001).]

 

Save the $3 on the pin removal tool. I was having a really hard time trying to figure out how to take those pins out...was about to go to Autozone and buy one of these little tools...but decided to try it one more time......on my first try with a thumb tack...they started popping right out.....pissed me off especially since I had already broken the connector and bought a new one and a bunch of other crap.

 

Please, do not cut up a factory harness like 89rs mentioned unless its already beyond repair. Stock harnesses are next to impossible to find in junkyards, dont ruin one if you dont have to. You can pick up ECMs with harness ends on ebay all the time for like $30-40. If you do find a complete harness and dont want it, Let me know i've been looking for one for a while now.

about your question, there are only a few wires shared in common with the chassis harness from the ecm harness. The speedo wires, the aldl wires, and some power and ground i think. Splicing it in to the chassis harness shouldn't be too difficult, just get some good diagrams for the years your parts are.

 

All you would have to do is add the vss wires, and the map sensor wires. You would not have to cut the harness at all on a mass air/ speed density swap. Just put the wires you need to add in a seperate loom and run them in to the car by the ecm. I had to cut up mine and spice cause my car had tbi. If you don't feel comfortable with wiring/repinning, I wouldn't do it. But it will save you alot of cash. I don't think it will ruin a harness to cut it up. As long as you solder, heatshrink and tape and put back into the looms like I did. If he was planning on buying a sd harness anyway, what would he have to lose, cutting up the harness. Worst case, he buys the new harness, best case he keeps $600 in his pocket to buy other goodies. Good luck to you.
P.S. I like the thumbtack idea. Have to try that some time.

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89'Camaro Convertible,96'firebird wheels,79'Z28 hood scoop,soon to be a 350 tuned port injection engine, 3.27 posi disc brake rearend,36mm front sway bar, 24mm rear bar, all donated by a 89'Formula 350, Poly sway bar bushings and end links, Dark yellow green paint from Bonnevilles, tan www. mrmikes.com leather interior,Macewen white face gauges.
Dreaming of a RamJet 350,
Jet fan switch
180 degree thermostat
Flowmaster cat back system
2nd place is always the first loser!

 

cfabe, you looking for a speed density harness I take it. If someone is wanting to buy my complete maf engine wiring harness, let me know or make an offer. I have not found any complete sd wiring harnesses. I have got quotes for a new gm sd harness. It is 277 plus shiping. If I cant find one for a good price I will probably do that.

 

Where are you finding a new GM speed density harness for $277 ?

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1990 RS Camaro 305 TBI, 700R4 Tranny, 3" cat back system with flowmaster muffler, Edelbrock strut tower brace, rear panhard bar, and torque arm, Spohn subframe conectors and lower control arms, all polyurithene bushing under the car, KYB gas adjust shocks and struts, March underdrive pully system, Taylor 8mm plug wires, Accel super coil, K&N air filter, Hypertech chip, GM Aluminum driveshaft, 3.42 Zexel-Torsen Rear end with superior 28 spline alloy axles, and Summit aluminum rear end girdle, Killer sound system, Many new mods to come (swap to 350 TPI comming soon)