Is anybody capable of tuning the 3.5/3.9l PCMs to function as stand-alone?

[flatlander757]

I am very much so wanting to use the 3.9l "LZ9" motor for it's SUPER compact size and weight. It uses the GM 60 degree bellhousing so adapting to a manual is no problem, or using a TF904 or 700R4 is no problem either(still unsure).

I am not too keen on trying to make something like Megasquirt work to run it... especially with the variable valve timing. I'd prefer to just have a factory PCM tune run everything as it normally would... I just need a PCM that is tuned to delete shit like the transmission and all the bullshit on the CAN bus.

I suppose worst case scenario I could run a later model 3.4l V6(same architecture... the new motors are based on the old 2.8/3.1/3.4) with a bit less power and torque and complexity. I am looking to shed an assload of weight from my TJ, and this would help. Even if I were to lose a bit of power, it would still probably "feel" faster with 3200lbs and 180hp than it would with 4600lbs and 190hp that it is rated at now.


Anyways... does anybody know who can tune the PCM to remove extra bullshit so I can run just the 3.9l LZ9?

[American Rock Rods]

No personal experience with that setup, but I've used OEM PCM's before on random builds, and kept the entire CAN bus system, except for what I didn't want.

They would always throw DTC's for the missing systems, but would work fine for controlling whatever I kept in place. So auto trans, cluster, airbags, radio, etc wasn't communicating, but everything else was. The only mandatory thing is if there is a passlock/skim. You usually can't get around that. But you will have a boatload of codes. One to three for EACH missing system, and they will be current codes on every single key on cycle, so no chance of clearing them.

One other option, is to buy a brand new PCM after you wire it in. Most CAN setups aren't configured at first. When you plug it in and power it up, it sends out a signal over the CAN(basically a what's up, who is here message), and each module responds that it is there. If it doesn't see a module the first time you plug it in, it doesn't know any better, and never knows to look for that specific module. Every time you power it up, it looks for new modules, as well as the specific modules it has seen before.

Manufacturers do this so they can use one PCM program over a huge variation of options.

I know for a fact that this works with SOME PCM's, because it has been used to bypass the need for a SKIM/Passlock type sensor. I also know that if one day you plug/wire a new module into the CAN, it will always look for that module from that point forward, even though it didn't before. Back in the day, I inadvertently activated the SENTRY system on a Chrysler that didn't come with it. One that according to Chrysler, wasn't SENTRY capable. I had to wire in the full setup and have the guy switch to a SENTRY key for his ignition, otherwise the car wouldn't start.


Again, I have no personal experience with that exact PCM, so I can't promise it works that way. Best thing to do is talk to a GM Master tech and ask him about PCM's learning the CAN bus system.

[flatlander757]

Originally Posted by American Rock Rods

No personal experience with that setup, but I've used OEM PCM's before on random builds, and kept the entire CAN bus system, except for what I didn't want.

They would always throw DTC's for the missing systems, but would work fine for controlling whatever I kept in place. So auto trans, cluster, airbags, radio, etc wasn't communicating, but everything else was. The only mandatory thing is if there is a passlock/skim. You usually can't get around that. But you will have a boatload of codes. One to three for EACH missing system, and they will be current codes on every single key on cycle, so no chance of clearing them.

One other option, is to buy a brand new PCM after you wire it in. Most CAN setups aren't configured at first. When you plug it in and power it up, it sends out a signal over the CAN(basically a what's up, who is here message), and each module responds that it is there. If it doesn't see a module the first time you plug it in, it doesn't know any better, and never knows to look for that specific module. Every time you power it up, it looks for new modules, as well as the specific modules it has seen before.

Manufacturers do this so they can use one PCM program over a huge variation of options.

I know for a fact that this works with SOME PCM's, because it has been used to bypass the need for a SKIM/Passlock type sensor. I also know that if one day you plug/wire a new module into the CAN, it will always look for that module from that point forward, even though it didn't before. Back in the day, I inadvertently activated the SENTRY system on a Chrysler that didn't come with it. One that according to Chrysler, wasn't SENTRY capable. I had to wire in the full setup and have the guy switch to a SENTRY key for his ignition, otherwise the car wouldn't start.


Again, I have no personal experience with that exact PCM, so I can't promise it works that way. Best thing to do is talk to a GM Master tech and ask him about PCM's learning the CAN bus system.

Thanks for the input!

FWIW I emailed HPTuners and got this reply back:

We support:

06-11 Chevrolet Impala 3.5, 3.9 2 6
06-10 Chevrolet Malibu 3.5, 3.6, 3.9 (3.5 in 07+ only) 2 6
06-07 Chevrolet Monte Carlo 3.5, 3.9 2 6
06-09 Pontiac G6 3.5, 3.6, 3.9 (3.5 in 07+ only) 2 6
09-11 Buick Lucerne 3.9

You are able to disable what you need to!

HP Tuners is not a traditional "handheld" device. It is much more powerful!
HP Tuners is a software suite that consists of a data logger, and a file
editor. This puts the control in your hands! We have a very supportive
forum that can help to guide you through the factory PCM so you can extract
all of the horsepower that you need! HP Tuners products do not come
supplied with a tune; however, you will have access to a repository of tunes
that you can reference. HP Tuners offers two MPVI Interfaces, the Standard,
and the Professional.

Where they differ is the PRO offers stand-alone data logging that allows you
to scan the car without hauling a computer along with you. The PRO also
accepts 0-5V inputs so that you can log air fuel ratio (or other
information) along with your OBD2 parameters. With that said, I would
seriously consider the MPVI Pro if you have (or are planning) any sort of
modifications to the vehicle(s) you will be tuning as this will allow you to
data log your Air Fuel Ratio etc. and display it right along with the
parameters logged with HP Tuners Scanner. This eliminates the need to
analyze data from a separate software system, or worse yet, write down the
AFR at certain RPM and load points. Otherwise, if you will not be modifying
the vehicle, the Standard will be more than sufficient.

When you purchase the HP Tuners VCM Suite or Scanner, you receive the
interface, cables, and a cd. You will need to supply external data
acquisition that you desire, such as an Air Fuel Ratio Meter (if logging
with the PRO, must have 0-5V output) the vehicle to tune and the laptop.

You can purchase either the MPVI Standard or the Pro directly through us, or
through a reseller. We build to order and ship in 5-7 days, and the
shipping is UPS ground. Resellers can get you product more quickly, as well
as offer calibration support, which we do not. If ordering directly, please
do so here: http://www.hptuners.com/order.php

If you want to purchase through a reseller, let me know whether you are
looking for a Pro or a standard, and whether you are looking for help with
your tune.

We are also working on more Ford coverage and Dodge, and the same piece of
hardware works for all three! All you would need to do is purchase Ford or
Dodge Credits.

I hope this helps you make a decision!

Please see our demos here:
http://www.hptuners.com/forum/showthread.php?t=5058

Thank you!

Jay
HP Tuners

Pretty generic reply, but it answers my question. Seems like as long as I get a 3.9l PCM that is NOT from an 07+ G6 or Malibu(but 06 is OK, and other model 3.9l PCMs are OK) then it can be tuned by somebody with the HPTuners VCM suite.