Years ago I blew the engine on my 2006 SE I4 going up a mountain in northern Nova Scotia. To my wife's considerable chagrin, it's been in our garage since I towed it back to New York. I recently bought a 1984 2M4 with 4-sp manual in good condition (except for weathered paint) with 34K miles on it - and promptly blew its motor driving it the short distance home.

I intend to begin an LX9 3500 swap this coming fall and have been studiously reading everything I can on the subject online. I want to use a stock PCM from a 2005 Pontiac G6 # 12591279 as it was used in both LX9 3500/auto and LZ9 3900/auto or non-electronic manual vehicles as I will be using the 2M4's 4-sp transmission for now. I wish to preserve some BCM-based options such as cruise control and A/C. I also wish to
switch from the DBW throttle to a cable-operated, larger throttle body. (No, I do not wish to swap an LZ9 3900 or a 3800SC instead)

PCMPerformance states on their website that they work with this G6 PCM and can set custom options on it ( https://www.pcmperformance....mming.html#SUPPORTED ). However, they claim a steep price for their services at a stated $400. Much of the available reading on PCM options and programming is rather dated. I'm sure that the art has progressed since, but I can't find much beyond either regressing to the 3400 engine's control system and hardware and, of course, the inevitable 3800SC advocacy comments.

Has anyone accomplished an LX9 3500 swap using a 2005 Pontiac G6 PCM? Can anyone recommend a source for reprogramming same at a reasonable cost? Any helpful advice on accomplishing this swap this way?

My intention is to leave the LX9 as stock as possible and perhaps reserve an option to experiment with adding a turbo in the future if I feel masochistic enough.

My first task will be to dismantle and dispose of the resulting remains of the '86 2M4 that occupies our garage to preserve domestic tranquility

I appreciate in advance any helpful input on this project.

Steve Mushynsky

1984 Fiero 2M4
34K miles

1986 Fiero SE I4 (donor)
Lots of good miles. One very bad mile.

[This message has been edited by SteveMushynsky (edited 07-24-2019).]

Welcome to the forum, Steve. I'm one of the resident "tuners" here. Let me see if I can answer your questions...

According to my information, the 3500 LX9 was only produced for 3 model years (2004-2006) and it was the only version of 3.5L (3500) to not have VVT (variable valve timing).

Of the three main companies that make custom tuning software that works with OBD2 GM car/truck V6 ECMs and PCMs (Tunercat, HP Tuners, and EFI Live), NOBODY officially supports any LX9 computer. However, I found that HP Tuners "unofficially" supports the 2005 Chevy Uplander LX9 computer. That being said, it is unclear if HP Tuners can disable VATS in this system (which is going to be essential for any swap unless you want to also install the BCM and VATS system from the donor vehicle into your Fiero).

The 12591279 part number PCM you cited in your post was NEVER used with the 3900 LZ9, according to AC Delco online parts catalog: https://parts-catalog.acdel...=1049&parttype=10543

You also cannot switch to a cable-op throttle body if you intend to use a DBW computer (such as the 12591279 computer you cited). These newer OBD2 V6 computers will only work with a DBW (drive-by-wire) throttle body. If you want to use a cable-op throttle body on your LX9 engine, you would need to also use an older computer which is going to be a problem. The older computers are designed to work with an older type of crank sensor, reluctor, and ignition system than the LX9 and newer generation engines use. So in order to use an older computer that would permit the use of a cable-op TB, you would need to retrofit the LX9 with an older type crank trigger which would probably need to be a custom, external arrangement.

But before you go to the trouble of doing that, I think it might be worth exploring the possibility of getting the 05 Uplander LX9 computer programmed to work in your swap (using a DBW TB). While I offer custom tuning services (and I can use HP Tuners to tune an 05 Uplander LX9 computer), I can't guarantee I will be able to deactivate VATS in it nor can I guarantee I can make this computer work flawlessly with a manual transmission if we are limited to using the Uplander OS (because the Uplanders were never offered with manual transmissions).

-ryan

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More is more. Less is not enough.

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

[This message has been edited by Darth Fiero (edited 07-22-2019).]

Hello Darth. I've read many, many of your posts in my research. Thank you for responding. I am appropriately honored.

Per the AC Delco resource, I see that the ECU for the 2006 G6 3.9L manual transmission version is a different part number from my 2005 G6 3.5L. I also noticed that the auto and manual transmissions for the 2006 G6 3.9L are controlled by the same TCU part number. I take it that the ECU communicates with the TCM in the same manner regardless of the transmission options therein, but with differing data options communicated.

So with the same engine, the same PCU # works with either transmission type. For a manual transmission, the ECU needs at least an input from a transmission VSS, correct? (Please bear with me - I'm learning here)

So, to be proper, I would need to find an ECU from an LX9 equipped vehicle with a manual transmission, right? Only there were no LX9 vehicles with manual transmissions, I think, and the LX9 and LZ9 don't share ECU part numbers, true?

Is there any developed wizardry among the ECU reprogramming world to get around this conundrum?

Reading your prior reply, please note that the Uplander ECU is the same manufacturer part number that I've already obtained that is taken from a 2005 Pontiac G6 with LX9 & auto transmission: Part # 12591279. This is my starting point - unless, of course, I need to start with something else.

I also note that the VIN eighth digit for this and the rest of the 2005 GM LX9 minivans is "L", rather than "8" as for the non-minivan cars. I assume this denotes an exhaust and accessories difference to accommodate the minivan platform.

As to the VATS/BCM issue, I'm actually not averse to adapting my Fiero to a VATS pushbutton start system with the BCS's cruise control feature and A/C, too. It seems an interesting challenge and besides, my son - who is a certified Toyota master mechanic - has done the equivalent with his engine-swapped MR2. He does tuning for Toyota hardware, but is unfamiliar with and has not the equipment for GM stuff.

If all else fails, I will go with the 3400's system, but it seems a shame to go backward. Or, perhaps, I simply don't know better at this point. It seems a worthy windmill to charge at, though.

I would sincerely appreciate any helpful info I might glean before I get to the assembling hardware stage.

BTW, I'm in no hurry to complete this project. I'm retired and have all the time I'd need and spreading out the expense is a good thing. It's the journey that's the thing

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Steve Mushynsky

1984 Fiero 2M4
34K miles

1986 Fiero SE I4 (donor)
Lots of good miles. One very bad mile.

[This message has been edited by SteveMushynsky (edited 07-24-2019).]

Thanks for the reply. Milzy Motorsports advertises a complete 3500 swap solution using 3400 tech and appropriate parts at https://www.milzymotorsports.com/3500-swap/ . This is my fall-back solution.

Ideally, I'd like to use a 2005 ECU/PCM plus DBW pedal, BCM & TCM as needed to use the newer tech control system. I'd like to use a larger throttlebody, but don't yet see how I could do that if I keep the DBW system. This is a learning experiment project for me, inspired by my son's completed similar projects with Toyota MR2s. He, however, is a Toyota Master Mechanic and I am most definitely not.

I've seen the diff between the minivan and the car exhaust manifolds. I'm not up to doing a performance header set initially and may want to experiment later with a low psi turbo add-on for poops and giggles. One big exhaust pipe seems a useful path toward that, later.

Actually, it took me a while to get up the nerve to decide to swap a new motor into my '84 2M4 as I had historical plates on it and wanted to restore it to original condition. Minus the blown Iron Duke and the sunburned body paint, the car is in excellent condition with a pristine interior and almost no rust anywhere. It was in a barn for many years and I picked it up for $1,000 a couple years ago. I drove my other (now donor) Fiero for years and lots of miles around the Northeast and Canada and enjoyed it greatly. I also had a third Fiero, but that one tried to kill me. PO had swapped the 4-cyl that was on it when I bought it, but failed to properly torque one of the rear trailing arms. Not fun when it broke loose at 70 mph on the highway - Big, swooping "S" turns in traffic until I got it slowed down. Parked it, kicked the crap out of it and got rid of it shortly after. Had Fiero withdrawal for a time. Now retired and feeling well enough to play with another one. I will be dismantling the donor Fiero in my garage shortly for salvageable parts, if anyone needs stuff. It's a red 1986 Fiero SE 4 cylinder.

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Steve Mushynsky

1984 Fiero 2M4
34K miles

1986 Fiero SE I4 (donor)
Lots of good miles. One very bad mile.

[This message has been edited by SteveMushynsky (edited 07-24-2019).]

quote Originally posted by SteveMushynsky: Thanks for the reply. Milzy Motorsports advertises a complete 3500 swap solution using 3400 tech and appropriate parts at https://www.milzymotorsports.com/3500-swap/ . This is my fall-back solution. Ideally, I'd like to use a 2005 ECU/PCM plus DBW pedal, BCM & TCM as needed to use the newer tech control system. I'd like to use a larger throttlebody, but don't yet see how I could do that if I keep the DBW system. This is a learning experiment project for me, inspired by my son's completed similar projects with Toyota MR2s. He, however, is a Toyota Master Mechanic and I am most definitely not. I've seen the diff between the minivan and the car exhaust manifolds. I'm not up to doing a performance header set initially and may want to experiment later with a low psi turbo add-on for poops and giggles. One big exhaust pipe seems a useful path toward that, later. Actually, it took me a while to get up the nerve to decide to swap a new motor into my '84 2M4 as I had historical plates on it and wanted to restore it to original condition. Minus the blown Iron Duke and the sunburned body paint, the car is in excellent condition with a pristine interior and almost no rust anywhere. It was in a barn for many years and I picked it up for $1,000 a couple years ago. I drove my other (now donor) Fiero for years and lots of miles around the Northeast and Canada and enjoyed it greatly. I also had a third Fiero, but that one tried to kill me. PO had swapped the 4-cyl that was on it when I bought it, but failed to properly torque one of the rear trailing arms. Not fun when it broke loose at 70 mph on the highway - Big, swooping "S" turns in traffic until I got it slowed down. Parked it, kicked the crap out of it and got rid of it shortly after. Had Fiero withdrawal for a time. Now retired and feeling well enough to play with another one. I will be dismantling the donor Fiero in my garage shortly for salvageable parts, if anyone needs stuff. It's a red 1986 Fiero SE 4 cylinder.

I'm all about using the stock computer, but in this instance, it's really not a great idea, there is almost no support for it, it really is the better option to use a 3400 PCM, a 7730/obd1, or megaquirt. FYI, MS3x, or an MS3 pro supports the stock LX9 trigger wheels, and coil per cylinder ignition. I would tell you to check out my build thread, but almost all the pictures are gone, and it's a bit out of date, my thread on RFT is much more up to speed though.


I'm not sure if the 60V6 forum is working again, but there's a few of us there who are pretty knowledgeable about these little engines.

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"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

"The day I tried to live, I stole a thousand beggars' change and gave it to the rich."
http://www.fiero.nl/forum/Forum2/HTML/119122.html

[This message has been edited by SteveMushynsky (edited 07-24-2019).]

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"I am not what you so glibly call to be a civilized man. I have broken with society for reasons which I alone am able to appreciate. I am therefore not subject to it's stupid laws, and I ask you to never allude to them in my presence again."

"The day I tried to live, I stole a thousand beggars' change and gave it to the rich."
http://www.fiero.nl/forum/Forum2/HTML/119122.html

Originally posted by ericjon262:

quote you *MIGHT* be able to run the stock 3500 crank and cam sensor with the 3400 computer with some tricky programming.

Actually, it is running an LX9 with stock crank and cam sensors with an LX9 computer # 12591279 in a Fiero with a non-electric manual that I am inquiring about, not with a 3400 computer.

quote the lack of support is my reason for ditching stock and going with an MS3pro,

Understood, but investing well over $1,000+ into a Megasquirt custom engine management solution is not in my picture.

quote you have two paths, a known, and a unknown, one you will be taught, and one will teach you, choose carefully.

Pardon. I'm sure you did not intend it to be so, but the above might come across as being a bit condescending in tone to a cranky old dude. I am but seeking progress in the hope that it will indeed teach me and in the process maybe teach others. If my goal turns out to be not possible at present, so be it. Sometimes though, tilting at windmills does bring positive results after all. One can only try.

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Steve Mushynsky

1984 Fiero 2M4
34K miles

1986 Fiero SE I4 (donor)
Lots of good miles. One very bad mile.