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Thread: Which OS / Computer to use for 3 bar setup

  1. #1

    Which OS / Computer to use for 3 bar setup

    I have an 87 GN motor (3.8 turbo V6) that I am going to do some experimenting on.

    I have all the factory harness and computer, but the factory computer is very limited. I could convert it over the XFI, but that is like $2K. So I figured I'd see if I could get it to run on a newer GM computer. I'm just wondering what the best option is in the v6 arena to use as a starting point. I knew in the past the v6 options were quite limited.

    I understand that I have to have a new harness and computer, convert over the crank sensor, cam sensor, etc... I can do all that. But before I go modifying anything I need to figure out what is the best starting point from a year/computer/harness/sensor standpoint.

    If there aren't any workable v6 options my question would be if you can change the number of cylinders and firing order in a V8 OS and use it as there is a lot more support on the v8 side.

  2. #2
    Potential Tuner
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    I have a p59 v6 blazer computer. I would. Look into going this route. When I pulled the tune out and had a look, it shows it as being 3 bar available upgrade. It's looks like the common 411 pcm. 411 is the blue red connectors. This one has the blue green connectors. You can use the red blue harness easily with these blue green pcms as well.
    I would assume there would be a bunch of details to work out, but it looks like there is full 3 bartuning capability on these V6 blazer pcms.

  3. #3
    Tuning Addict 5FDP's Avatar
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    I'd almost recommend a MS3 pro for this kind of setup.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  4. #4
    Senior Tuner LSxpwrdZ's Avatar
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    The problem is you are limited to the V6 OS's due to crank trigger phasing. You put a V8 OS in it and it's going to be looking for coil packs, 24x crank by 1x cam signals and fire each cylinder sequentially every 90deg.

    The V6 OS still uses a distributor which obviously fires every 120deg mechanically. The crank trigger is a "low res" trigger wheel. As far as injectors I'm not positive if it even fires those sequentially being that the crank trigger is in low res mode. If you can fit the GN with a GM distributor and a "low res" crank wheel this is fully possible as the P01 and P59 PCM's fully support custom OS's up to 3bar on particular base OS's.
    James Short - [email protected]
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  5. #5
    Yeah in looking at it, I don't think the v8 OS will work. What I was trying to find was a v6 OS that was sequential injector, individual coil, and 3bar OS capable.

    5fDP, Mequsquirt is an option I have looked at, I'm just trying to see if I can do something with a GM computer.

  6. #6
    i420tom it looks like the p59 is sequential coil, so that might be an option. Do you have one?

  7. #7
    Potential Tuner
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    I have two. I am about to flash them to 3 bar V8 tunes though.. both are 1257405 OS V6 upgradable to 3 bar 1262050 ive never implemented v6 stuff... so these are just what I noticed in my 4.3L pcms that I picked up.
    Last edited by i420tom; 02-02-2017 at 12:33 PM.

  8. #8
    Senior Tuner LSxpwrdZ's Avatar
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    Did the newer V6 (03-07) trucks come with coil packs rather than running a distributor? I'm almost positive they still had distributor but could be wrong. Below is a screen shot of the calibration options table of a 2004 V6 Silverado. You'll notice "Crank Low Res" is still enabled which from my understanding signifies the crank is a 4x wheel and doesn't have the resolution necessary to sequential fire the injectors. I could be completely wrong however. I'm curious to know.

    Low Res.png
    James Short - [email protected]
    Located in Central Kentucky
    ShorTuning
    2020 Camaro 2SS | BTR 230 | GPI CNC Heads | MSD Intake | Rotofab | 2" LT's | Flex Fuel | 638rwhp / 540rwtq
    2002 Camaro | LSX 427 | CID LS7's | Twin GT5088's | Haltech Nexus R5 | RPM TH400