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3.1L VIN T swping to 3.1L LG5 VIN V


cutlass_driver91

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okay guys im swaping the 3.1 MPFI (non turbo) VIN-T for the 3.1 MPFI Intercooled turbo LG5 VIN V what all do i need to do with the wireing harness and ECM???????? im at a loss could i just re-programe the stock ECM with a new chip or do i have to put the 1990 pontiac grand prix STE Turbo wireing harnsse in???????????????????HELP!!!!!

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Guest TurboSedan

if you have the TGP wiring harness available just use that - that's what i did with my car. it plugged right into the Cutlass firewall connector and everything else for that matter.

 

as far as modifying the NA 3.1 harness....i'm really not sure but it shouldn't be too hard. heck if you use a MBC and delete the EGR then all you'd probably have to do is extend the IAT sensor wires and modify your MAP sensor connector with a Dremel (so it will plug into a 2-bar MAP sensor) but that only takes like 5 seconds.

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just for shits a giggles, did you happen to ask if that GM Performance computer operator has ever done a 3.1T ---> 3.1V swap? I doubt it. In fact, I wouldn't be the least bit surprised if he didn't know his ass from his elbow when it came to the differences between the harnesses. You WILL be causing yourself more work and distress and splitting and pen torching and re-routing wires, and etc and etc if you don't swap the harness. If you came here for advice, your best bet would be to re-read what has been written to you, in an advising manner, and not to trust that tool salesman at GM.

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Guest TurboSedan

as far as modifying the NA 3.1 harness....i'm really not sure but it shouldn't be too hard.

 

my 1992 Cutlass 3.1 Harness and the 1990 TGP 3.1 Turbo had very diffrent wiring and wiring colours.

 

took me about a week working 4 hours a night with both GM service manuals to get the engine working.

 

do what Josh did and take the whole harness and plug it into the firewall plug.

 

save yourself some greef :wink:

 

that's strange, my 3.1 NA VIN 'T' harness was pretty much just like my TGP harness....the only differences being the IAT, EGR and the TGP harness has a boost control solenoid (also just remembered - the O2 sensor is in a different place of course). i didn't bother comparing colors of anything and didn't really see the need to as long as you connect all of the connectors to their respective places. if are going to disable EGR and use a MBC like i do, then the only things you need to worry about is lengthening the IAT & O2 wires and modify the MAP sensor connector which could all easily be done in 10 minutes. although, i did not do it this way so maybe there's something i don't know about? but yeah, i just used the TGP harness, which went right into my Cutlass - no modifications required. i did have to modify quite a bit for the 5-speed though.

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Guest TurboSedan
well i found the eninge and tranny both from auto zone so wouldnt it be common sense that they would carry a wireing harnesse oh here is a website that has a 88-91 body kit http://www.wickedbodies.net/

 

no auto parts store, not even GM will sell you a complete Turbo 3.1 engine (or the TGP specific automatic transmission for that matter). sure they might sell you the shortblock but you simply can't get the TGP specific stuff like rear exhaust manifold, crossover pipe, turbocharger, intercooler, radiator, wiring harness etc etc etc anywhere but from someone as a used or rebuilt part. the only way you are going to find all of the things you need is by either buying all of the pieces needed seperately from forums or ebay. if you get real lucky you'll find a complete junker/wrecked TGP/TSTE as a donor vehicle. if you are not extremely familiar with the entire drivetrain of the TGP i would not suggest such a project.

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Guest TurboSedan
yea i just got off the phone with GM Performance and the guy i spoke with said all i had to do was re-map the ECU and just up grade the the chip

 

you do nothing with the ECM itself. leave it alone. the TGP (LG5) and NA 3.1 (LH0) use the very same 727 ECM. the memcal (which contains the chip aka EPROM) is what needs to be replaced. the memcal can easily be unplugged from the ECM and swapped with a TGP memcal.

 

the TGP memcal has the 2-bar calibration and fuel/spark maps etc. required to run the Turbo 3.1 LG5 engine.

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I hate to say this but Autozone advertises getting used parts now. Wouldn't be hard to find a turbo 3.1 from an online salvage yard listing. If that's what they have.

 

They will not know what they are looking for, and even if they do.... try finding on....

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