1987 5.7L TPI in 1988 Body
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Car: 1987 Pontiac Trans Am GTA
Engine: 5.7L V8
1987 5.7L TPI in 1988 Body
Hello,
I have a few quick questions about an engine swap/transfer, specifically relating to the wiring/harness. I'm transferring the engine from a 1987 5.7L TPI GTA (digital dash) into a 1988 (analog dash) that originally had a 305 TBI, and am trying to figure out which engine harness I should use. I have the harness from the 1987, but after reading on here and elsewhere I learned that the 1987 has two harnesses (engine & ECM), while the 1988 only has large one...and now I'm not sure if the 1987 harness will plug into the 1988 body or if the two are interchangeable at all. Does anyone know if the two 1987 harnesses will work with the 1988 body (specifically going from a digital dash to a non-digital), and/or what changes must be made? Or should I look for a 1988 harness?
Any information would be greatly appreciated. Thanks.
Brendan "NinjaNife" West
P.S.
I tried looking up the engine wiring diagrams in my service manual, but there doesn't seem to be an L98 in the book...does one of the other engine models match the L98 in respect to wiring?
I have a few quick questions about an engine swap/transfer, specifically relating to the wiring/harness. I'm transferring the engine from a 1987 5.7L TPI GTA (digital dash) into a 1988 (analog dash) that originally had a 305 TBI, and am trying to figure out which engine harness I should use. I have the harness from the 1987, but after reading on here and elsewhere I learned that the 1987 has two harnesses (engine & ECM), while the 1988 only has large one...and now I'm not sure if the 1987 harness will plug into the 1988 body or if the two are interchangeable at all. Does anyone know if the two 1987 harnesses will work with the 1988 body (specifically going from a digital dash to a non-digital), and/or what changes must be made? Or should I look for a 1988 harness?
Any information would be greatly appreciated. Thanks.
Brendan "NinjaNife" West
P.S.
I tried looking up the engine wiring diagrams in my service manual, but there doesn't seem to be an L98 in the book...does one of the other engine models match the L98 in respect to wiring?
Last edited by NinjaNife; 06-01-2016 at 01:15 PM.
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
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Re: 1987 5.7L TPI in 1988 Body
Use the harness for the body of the car.
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Car: 1987 Pontiac Trans Am GTA
Engine: 5.7L V8
Re: 1987 5.7L TPI in 1988 Body
Okay, I'll see if the harness that was in the body wasn't completely hacked to bits haha. One question though: the body had a 305 L03 in it (the VIN decoder says E = 305 ci V8 LO3 (1988-1992)); should I look for a 1988 L98 harness specifically for my engine, or will the 305 harness work (perhaps with some modification)? I don't know much at all about the difference in wiring sorry
Thanks for the help.
Brendan "NinjaNife" West
Thanks for the help.
Brendan "NinjaNife" West
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: 1987 5.7L TPI in 1988 Body
That may change things a bit. thought they were 2 5.7 cars.
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Car: 1987 Pontiac Trans Am GTA
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Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: 1987 5.7L TPI in 1988 Body
I know the differences but not in the detail you need. You need 2 service manuals
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Re: 1987 5.7L TPI in 1988 Body
Brendan "NinjaNife" West
Last edited by NinjaNife; 05-31-2016 at 10:07 PM.
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Re: 1987 5.7L TPI in 1988 Body
You didn't state the '88 was TBI, so the natural assumption was both the '87 and '88 were TPI. I made the same assumption reading what you posted.
You're going to have issues regardless of what you do. The '87 accessories were different than '88 accessories, which switched the AC and alternator side-to-side, and connectors changed. You'll certainly want to use the '87 engine harness, although the TBI harness can be repinned to TPI (I know one guy who did that - one...). TBI used a VSS buffer that TPI didn't use, you should be able to search to figure out what to do about that.
Probably the most knowledgeable harness guy on the Board is Pocket. Perhaps he'll chime in.
You're going to have issues regardless of what you do. The '87 accessories were different than '88 accessories, which switched the AC and alternator side-to-side, and connectors changed. You'll certainly want to use the '87 engine harness, although the TBI harness can be repinned to TPI (I know one guy who did that - one...). TBI used a VSS buffer that TPI didn't use, you should be able to search to figure out what to do about that.
Probably the most knowledgeable harness guy on the Board is Pocket. Perhaps he'll chime in.
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Car: 1987 Pontiac Trans Am GTA
Engine: 5.7L V8
Re: 1987 5.7L TPI in 1988 Body
You didn't state the '88 was TBI, so the natural assumption was both the '87 and '88 were TPI. I made the same assumption reading what you posted.
You're going to have issues regardless of what you do. The '87 accessories were different than '88 accessories, which switched the AC and alternator side-to-side, and connectors changed. You'll certainly want to use the '87 engine harness, although the TBI harness can be repinned to TPI (I know one guy who did that - one...). TBI used a VSS buffer that TPI didn't use, you should be able to search to figure out what to do about that.
Probably the most knowledgeable harness guy on the Board is Pocket. Perhaps he'll chime in.
You're going to have issues regardless of what you do. The '87 accessories were different than '88 accessories, which switched the AC and alternator side-to-side, and connectors changed. You'll certainly want to use the '87 engine harness, although the TBI harness can be repinned to TPI (I know one guy who did that - one...). TBI used a VSS buffer that TPI didn't use, you should be able to search to figure out what to do about that.
Probably the most knowledgeable harness guy on the Board is Pocket. Perhaps he'll chime in.
Do you happen to know if the harness connectors (passenger interior and driver in the engine bay) are different? Or are the accessories within the engine bay just shifted around?
Thanks for the help.
Brendan "NinjaNife" West
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Car: 88 GTA
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Re: 1987 5.7L TPI in 1988 Body
I put my 1987 TPI Motor into a 1988 TBI body. I purchased a 1988 TPI Harness on ebay, since the accessories differ in location.. AC, Alt etc. Also, nice plus.. say goodbye to v-belts!!
I made sure I had both an 1987 and 1988 Helm manual handy as well. Ebay can help.
I ran an inline fuel pump. Just make sure your front cross car harness provides nice power to Fans, ECM, and MAF.
I just took mine out of storage (3 years), and I picked up electrical gremlins. I only noticed chew marks on a spark boot, but I suspect there may be more damage, since engine surges when wipers run. . Time to upgrade mains wires I guess, and give it a thorough checkup.
There is a connector by the radiator (orange 10 ga wire) for cross car. One was damaged on used harness. I butt spliced it. The connector was causing major ECM/driveability issues after swap. So I can't stress enough to make sure, ECM gets good power, as well as MAF, MAF burnoff relay.
I made sure I had both an 1987 and 1988 Helm manual handy as well. Ebay can help.
I ran an inline fuel pump. Just make sure your front cross car harness provides nice power to Fans, ECM, and MAF.
I just took mine out of storage (3 years), and I picked up electrical gremlins. I only noticed chew marks on a spark boot, but I suspect there may be more damage, since engine surges when wipers run. . Time to upgrade mains wires I guess, and give it a thorough checkup.
There is a connector by the radiator (orange 10 ga wire) for cross car. One was damaged on used harness. I butt spliced it. The connector was causing major ECM/driveability issues after swap. So I can't stress enough to make sure, ECM gets good power, as well as MAF, MAF burnoff relay.
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