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Thread: 3400 LA1 PCM w/ 282 Getrag

  1. #1
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    3400 LA1 PCM w/ 282 Getrag

    So, I just got my motor running with a VATS delete. I did some research on what to do about having a manual transmission with an automatic PCM, and all I found was 2 options.

    Copy tune from a manual equipped car
    or
    Delete A4 codes and raise Idle RPM

    Since the 3400 (and many of the 60* V6 motors) did not come with a manual transmission, my only true option was the latter, which has the car running fine at idle and revving it a bit seems fine. I'm waiting for the exhaust to be done, then I will be tuning the motor to the new exhaust/intake. Maybe I am just making a bigger deal than I need to, but I feel like that is not enough to make the car run fine while in gear.

    Main problems I possibly see:
    No Torque Converter
    Accell and Decel
    Clutch Engage
    Load between gears

    More I look at it, more it seems I just need to re-tune the motor without the torque converter and there won't be any problems afterwards. Should I just make all gear tables mimic each other? What about when I depress the clutch? Will this cause the motor to almost stall? I moved the lowest Idle to 800rpm for now, am going to re-tune my Idle and whatnot, but trying to figure out the transmission stuff first so my tune isn't all funky. I assume the car just needs to see the vss and it will use the accel and decel tables to help retard or advance timing? There is one pcm I think I can use as a reference, the G6 3900 has a manual transmission. I downloaded a stock tune from the repository and plan on looking into it.

    I plan on looking more into how to tune, the only tuning I've really looked in depth at yet is the Idle, I figure take it one step at a time so I don't mess anything up.

    Plan on figuring out:
    Transmission behavior and how it is linked to engine tune (that's what this post is about)
    Idle
    MAP or MAF? (I've seen the word speed density thrown around, still need to read up about this and whether to tune for MAP or MAF)
    Accel/Decel? (I am going to assume I need to change these tables due to my increased flow)

    Any help would be appreciated, otherwise I will plan on figuring everything out myself like how I made my wiring harness, rebuilt/ported my motor, and made my own 180* equal length headers. (Thank God that motor runs and sounds great we will see how it holds up) The tuning is just something I can see myself messing up over and over or banging my head against a wall for 2 months, this is my daily, and ive already spent 6 months on this swap so I am trying to finish tuning it before the end of the month.

    Here is a picture before I got it running:

  2. #2
    Advanced Tuner Dr. Nopps's Avatar
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    Cool! I loved the 3.1/3.4 engine from the first time I mashed down the throttle on one. One easy but crucially important thing on the FWD tranny swaps is editing in the new transmissions Drive Sprocket Ratio, but honestly going fom auto to a manual tranny would make that soo much less of a big deal, but I would do it anyway. Research (briefly) a tune from a manual 4 cylinder and you will see most transmission values either zeroed or maxed out. I think most of the real magic for a manual trans. tune is in the segment and my not be viewable or swappable with theese PCM's, especially without a true OEM manual tune to source from but shouldn't be a deal breaker or anything. Whenever the clutch is pressed (load between gears) RPM's might initially try to rise by 200 or so then settle and you could probably work on that and figure out a trick or two with some testing, trial, and hopefully little error. There should be less to worry about with the lack of a convertor, just a bunch of tables that won't do anything anymore, most likely you'll have to delete some DTC's. I personally would leave Acceleration Enrichnent & Decelleration Enleanment values themselves alone for now, mabey even forever. All I've done there is set the Accel. Enrich. Disable at WOT feature to: Enabled to turn that feature on, which should greatly help to keep your chosen Power Enrichment values on target. And most V6'ers just tune the Mass Air Flow table, leaving the VE (MAP) tables alone and are just fine, even when making modifications as drastic as adding a turbo - MAF tuning seems to be enough. But who knows? After you've nailed down all of this stuff you might just get bored one day, disable the MAF, try your luck at re-tuning the VE table before re-enabling the MAF, then do one final MAF retune just for shits & gigs. There should be really no harm in doing it either way, you definately wouldn't be the first on here to try that second method, just that the first way is easier. I have not yet seen anyone run a VE (MAP) only tune without a MAF on one of theese motors yet, so I would shy away from going that route.
    Last edited by Dr. Nopps; 11-14-2015 at 10:46 AM.

  3. #3
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    Well, I've been running the car for a while, it is much quicker than my Grand Am for sure. Car seems to run fine, I accidently left some tape on one of the heads I was using to mark the cylinders, and I think it isn't letting my head gasket seat correctly. At the time, i just chose to put the motor together, because the head bolts are torque-to-yield and i was hoping the tape didnt fall outside of the combustion radius. Seems I've got combustion leaking into my coolant and blowing my epoxy plugs on the side i left the tape in so I'm taking the motor back apart to fix this, but otherwise the only issue I have at the moment is an idle hunt. I think this is because I ported the motor, so it is breathing better and the computer is still trying to use the stock TPS values to idle, which with better flow, will make the TPS values not be true anymore. Otherwise, runs great. I am concerned about my spark advance though, I noticed these motors have a lot of spark advance compared to some others I've worked on. Im getting -22 at idle and up to -45 at WOT. I assume this is normal, but should I am wondering if I should change the idle values a bit since I have no Torque Converter anymore, I am not sure if that affects spark advance or not. Then again, I currently don't have my O2 sensor hooked up so maybe that is affecting my values a bit running in closed loop, though i couldn't find anything in the tables suggesting this is true.

    Anyways, Transmission related, to get the motor to run, i had to change VATS to serial and turn off the VATS DTC's. Also, whenever the car is started on a new charge (replaced, dead, unhooked battery), I have to pump the gas and keep the revs up while I start the car. In a Grand Am I believe this would be the equivalent of causing the Security light to turn on solid red, I have not figured out how to completely remove/trick VATS into being bypassed otherwise. I changed all transmission tables to the same as Drive, and changed my ratios to the 282 final drive and whatnot just like you had suggested. I raised my idle to 800 from 600 as well, but will probably play with it later once I fix my idle hunting issue, I heard this will help keep the motor from wanting to die when pressing the clutch in.

    Here is a video, car sounds amazing for a 60* V6. Runs pretty good for just a basically stock tune.
    https://www.youtube.com/watch?v=S6ypz81puAc

    Thanks for the tips Dr.
    Last edited by seizurenoodles; 01-28-2016 at 05:15 PM.

  4. #4
    Advanced Tuner Dr. Nopps's Avatar
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    It's not VATS, if it were you wouldn't be able to keep the car running no matter what trick you are doing with the throttle. Without the load from a torque convertor you can usually add a little timing over stock and the values you listed seem very normal for that engine. You absolutely need to fix that head leak and on top of that should also have the heads professionally inspected or skip a step and have them milled true anyway, and if you still feel like playing it super safe have the block zero decked, that way you'll be putting a motor back together knowing it's perfectly within spec. The idle could be affected by that leak, or lack of o2 sensor, IAC not able to keep up with extra ported flow untill engine warms up, or a MAF sensor problem/intake leak. I would hook the o2 sensors back up then just disable the fault codes for them, letting them work just without reporting errors. Eliminating each of those as a possibility should help you narrow down what the problem mainly is/was.

  5. #5
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    Thanks for getting back to me so fast. I already had the heads milled true, but not the block. Once I get to block back together and running I intend on hooking up the 02, was just trying to make sure it ran well in limp before I tried running in open. I found the tables for base timing, I might add some timing once I get all of the other tuning done. I was thinking my idle problem was probably a preset table somewhere that says to open up x amount for y amount of airflow, which y being different now that there is much more flow. I cleaned out my throttle body before putting the motor together, so I wouldn't assume it to be a stuck valve, but could be. Then again, with my assumed blown/unseated head gasket, its could totally just be coolant going into the combustion chamber. I also deleted the EGR, which could be a problem down the road that I need to tend to.

  6. #6
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    I have the motor from a 2001 grand am 3.4. using it in a rear wheel drive with an adapter and an older auto trans. this transmission it all mechanical and does not use electronic control. just wondering if I have to disable any transmission control for the engine to and computer to run properly?

    how did you disable vats?
    are you using a bcm? I am hoping I don't have to have one in order to run the motor.

    thanks in advance