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6th Gen ('00-'05): 2004 3800SC in sandrail - looking for some info

Old 09-20-2016, 12:23 PM
nitrosport_5's Avatar
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Default 2004 3800SC in sandrail - looking for some info

Hey guys, while i wait to get enough posts to make a wanted add, ill try and pick your brains on what i need to do.

My step dad and i are building a VW sandrail with a 3800sc engine out of a 2004 Monte Carlo SS. I have already acquired the adapters and everything i need to make this engine mechanically run and work in the rail, and have seen it done successfully so this is not the problem! the PCM is where i am unfamiliar and would like some information if possible.

To begin, i have a "friend"? who i had build a 700r4 transmission for my 1972 K20 restoration last year. He builds transmissions and on the side does LS conversions, wiring harness, and PCM flashing. Transmission works beautifully and i do believe he knows what he is doing. Anyways, he said he should be able to flash my PCM to get rid of anything i do not need, and thin out what we dont need from the wiring harness. Well, after about a year of him having my PCM, every time i bring it up he wont respond to me..... so i guess ive gotta find a PCM and wiring harness....... Anybody have one that they would want to sell?

The info i am looking for is, what wiring harnesses are compatable with this 3800sc from the monte carlo. DO i need to find a harness from a 2004 supercharged? or will the wiring harnesses from other models work just fine since i am going to be cutting them up anyways?

For the PCM, what all needs to be removed in order to alow the engine to run seperate from any of the body controls or security stuff on the car? I would also like to eliminate any unnecessary emissions stuff. I will be either buying a set of swap headers or building them.

And finally, is the HPTuners software suite somthing i can use to remove what i need from the PCM? At this point, i am willing to make the investment with the software to do the work, i can be certain that this will not be the last fuel injected GM engine that i swap into somthing. \

thanks in advance. hopefully you guys dont mind that i dont actually own the monte carlo, although i do have an 86 SS, thats close enough right!
Old 09-20-2016, 01:22 PM
turbo monte's Avatar
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Hey there, I seen someone else attempt this once and could never get it to run right and without ever getting to race it he sold the engine and turbo setup and went with a different engine. So I hope you have better luck making it work. Anyway, I would get a harness for your car specific year and sc to be certain it's correct. Then from there eliminate unneeded wiring from abs, cruise, ac, etc as this is what I did. Hpt will let you tune most stuff out but will not let you change the serial numbers of the pcm etc so that's where you would need dhp. But dhp is old and not made anymore so kinda hard to find one. Getting around all of the security I'm not sure how to accomplish that either but I'm sure it's able to be done.
Old 09-20-2016, 02:00 PM
nitrosport_5's Avatar
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Join Date: Sep 2016
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thanks for the reply.

My plan B is a megasquirt. ive seen that done on these engines as well, but i dont want to have to fight getting a base tune built for the thing if i dont have to.

there has to be a way to remove the security from these pcms. quite a few guys put these in fieros, so i guess that may be my next stop is asking those guys what they do!

i figured i have the best chance at finding parts here, so thats where i started.

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