2007 4.3L V6 swap - learning curve help please!

[dgiller]

I'm swapping a 4.3L V6 from a 2007 Silverado Classic (Gen III) into an old Volvo C303 military vehicle. The mechanical work is all done. I'm trying to sort the EFI, and I could use a little help. I'm a quick study but I'm new to EFI tuning. I have background in microcontroller programming and electronics so I understand the theory but am having to learn everything about these GM EFI systems.

I bought a PCM with the donor engine. It was advertised as being the PCM from the donor truck, but it isn't... not even close. It's from a 2003 S10 auto. I've also got another 2003 S10 PCM, this one manual. I had a bad engine harness and chopped it to make a bench harness for the PCMs.

I bought a FlashScan V2 and have read both of the PCMs (but not flashed them, so I haven't used any licenses yet).

Other pertinent info: drivetrain is assembled from a SM465, Ranger OD, and a Dana 18.

The two PCMs I have are:

Manual
Hardware 12570558 (per label)
OS 12579405

Auto (4L60E)
Hardware 12575502 (per label)
OS 12579405

I'm not certain I am identifying the hardware number for the PCM correctly.

My initial questions:

1. Does anyone know the LU3's well enough to tell me that the 2003 PCM/OS will work fine with my 2007 engine and engine harness? Should I just start with the PCM that's already configured for manual transmission and run with it? The 2003 harness was so different from the 2007 that that makes me nervous. The MAF is different too, as the 2007 apparently has IAT built in and the '03 doesn't (I have an '03 MAF that won't work with the '07 harness, and I don't know where the IAT goes on the '03 engine).

2. I'm expecting the answer to #1 is that I shouldn't try it. I'm wanting to get this thing running, and I'm not excited about buying a third PCM. I've shopped around and the closest I've found is an '06 Express Van PCM. The guy looking up the PCMs for me said the hardware part number is coming back the same all the way back to 2003 (didn't see the listings myself though).

These are 1mb PCMs as I am pretty sure the 2007 is. Can anyone tell me if I can flash a 2007 OS onto one of these two PCMs? Are all 1mb PCMs interchangeable (in terms of hardware)?

If so, can someone give me a stock tune/OS for a 2007 V6 Silverado Classic? (2006 is probably fine, as 2007 "classic" was just a carryover from the 2006 while they introduced the new E38-based trucks)

I looked at HoldenCrazy's repository and didn't find any 4.3's later than 2004.


General suggestions on the least painful way to get a baseline running truck that I can learn to refine the tune on later would be helpful too.

Thanks,
Dave

[ScarabEpic22]

OK, the 07 (NBS) uses an E37 ECM from GM, neither of the ones you have will work without swapping hard parts, the reluctor wheel is different I believe = new crank. Fortunately, E37 ECMs are DIRT CHEAP. Like 20 bucks shipped off eBay.

Check the seller scoobyinc out, here are some auctions:
4.3L V6 ECM Auction 1 (http://cgi.ebay.com/ebaymotors/SILVERADO-SIERRA-HHR-COBALT-IMPALA-G6-ECM-PCM-COMPUTER-_W0QQcmdZViewItemQQitemZ190428822890QQptZMotorsQ5f CarQ5fTruckQ5fPartsQ5fAccessories)
4.3L V6 ECM Auction 2 (http://cgi.ebay.com/ebaymotors/SILVERADO-SIERRA-HHR-COBALT-IMPALA-G6-ECM-PCM-COMPUTER-_W0QQcmdZViewItemQQitemZ190428152885QQptZMotorsQ5f CarQ5fTruckQ5fPartsQ5fAccessories)

Look at his seller page for more auctions.

Hmm, just looked and its outta a Classic Silvy, wonder if that's still using the LS1 PCM? There's a good chance if the motor's a true 07 that it will work, but Im not sure how to tell...

[dgiller]

Hi Erik,

Thanks... I wasn't very clear in my description, sorry. I've confirmed from the VIN code that the engine is from a Classic, and used an LS1 PCM.

I've done a bit more research and I think the answer to my question #1 is pretty clearly no.

I've got two 1Mb PCMs, both from 2003 S10 pickups, and I'm wondering if I can load a 2007 or 2006 OS and stock tune on one of these 2003 PCMs and will it work. I could just try it, but I'd rather not consume a VIN license if it's not going to work, so I was hoping someone would know.

I can pick up a later PCM for about $100, so if I have to roll the dice, I'll just buy a later PCM since that seems like a better gamble. I'd really hate to have EFILive go ahead and flash it, and have the PCM think it's working, later find some kind of problem that keeps it from running and wastes hours and hours of my time. But if someone knows which years of PCM will run which OS, that could clear up the question for me. I just hate to buy a third PCM if one of the ones I have will work.

I thought I read somewhere that the 2005+ LS1 PCMs are all the same hardware, not mentioning the 2003-4, which would hint that my 2003 PCMs won't correctly run the 2006/7 engine. But I'm hoping someone here would know the truth.

I've found a stock tune/OS from a 2006 Express Van, so that's a start.

Thanks!
-Dave

[ScarabEpic22]

Dave, I was stoked because EFI just released E37 support so I thought you lucked out!

Im 99% sure there are 3 LS1 PCMs: 97-98 512kb, 99-02/3 512kb, and 02/3-07 (classic) 1MB. I dont believe there are any differences between 03/04 1MB and So I believe you can full flash an 05/06/07cbs 4.3L V6 OS/Cal into your 03 1MB PCM and be ok. Just make sure you wire your harness like the 05/06/07 and NOT the 03. PCMs are interchangeable, its the OS/Cal and the wiring that sets each platform/model apart. So my E67 works in a CTS-V if flashed with a CTS-V OS/Cal, and a CTS-V E67 would work in my TBSS if I flashed the TBSS OS/Cal into it.

Someone can clear up the PCM issue soon, Im just not well versed with them. The P10 and E67 are where my limited knowledge lies currently.

Is the 06 tune from a V6? A V8 tune wont work.

[dgiller]

Erik,

Thanks, that would be good news if the 1mb PCMs are all physically the same, and can be interchanged by flashing a new OS on them. Sounds like you suggest I wait till someone else agrees with you before trying to burn a new OS.

I bought a new engine harness based on the VIN of the truck the engine came from, so I have the '07 4.3L Silverado Classic harness. I had a cheap '03 harness from eBay that I cut up to make a bench harness for programming the PCMs and to have a supply of TXL wire for wiring the engine harness into my truck, since I'm not running the Chevy fuse block that the engine harness plugs into.

The tune I found on the forum is a stock tune from a 2006 4.3L V6 Express Van 1500 with manual transmission. I'm going to keep looking to see if I can find a 2007 4.3 LS1 tune, or determine whether it's the same OS number as the 2006.

I looked on HoldenCrazy and I've been searching the forums for attachments that are stock tunes. Is there any other method I should be using?

Thanks a bunch for your help!

Cheers,
Dave

[dgiller]

My memory from bench to web is bad...

The 2006 tune I found is from a GMC Sierra 1500 4.3L V6, not from an Express Van. The Express Van was one of the physical PCMs available locally for purchase.

Here's the tune I found on the forum. I'd like for it to work, since I've got it and it came from a manual transmission vehicle. I guess the two remaining questions are:

1. Can someone else confirm the belief that I can flash this onto my 2003 1Mb PCM and it should work properly with the 2007 engine and harness, and

2. Will the 2006 OS run the 2007 engine to run properly.

This is a conversion and so we'll have to tweak it later obviously, but just looking for a combination that will start and run, and can later on be dialed in.

Thanks!
Dave

[ScarabEpic22]

I say wait for a little bit just in case something changed, although Id be willing to bet they're the same (and Im not a gambler ha!).

So you want a manual tune correct? Sounds like the one you have is your best choice for now. With the 07 Classic harness, its basically an 06 truck that GM was getting rid of old parts for so I cant imagine they changed very much from 06->07.

Once we confirm the 06/07 PCM is identical to the 03 1MB one, then I say you full flash that tune in, disable VATS, and plug it into the harness to see what codes (if any) you get.

[dgiller]

Thanks Erik.

I'm going to have to learn a little bit to get a good tune going. I already know that I'm going to have to compensate for:

- no VATS (trivial)
- no cats or post-cat O2s (off-road use only, etc). We'll have the normal pre-cat O2s.
- intake and exhaust will probably not be as efficient as stock
- we'll have to adapt a VSS and figure out the VSS input math. I don't know how important the VSS input is on a manual PCM.

But at least the thing should run if I get a stock tune.

I may post the PCM/OS compatibility question to the Gen III LS1 forum, as someone there may know, and I suspect there are lots more people watching that forum who would know.

Any opinion on how much I would give up if I tried to work out a speed-density tune and not use a MAF at all? Again, I'm new to all of this, but I pick things up pretty quickly.

Cheers!
-Dave

[ScarabEpic22]

Looks good for the disabled items, VSS Im not sure either honestly but in auto cars it's mainly used for shift point calculation. There might be a few VSS referenced tables though even for manuals, have to look through the tune and check.

I'd leave the MAF alone personally, being a stock motor the stock tune will be ok and just tune it normally using AutoVE. Easier for altitude compensation than SD.

[Taz]

Hello Dave,

I responded earlier to your question in the Gen III forum – but it didn’t contain all of this information – so it changes your situation a little. I won’t restate the previous post, but you will probably need to refer to it.

As I understand it now, you have:
• a 4.3L and manual trans from an ’07 Sierra 1500 2 wheel drive
• “new” ’07 wiring harness
• ’03 MAF with a divorced IAT
• two ’03 S10 PCMs – one auto tune, one manual tune

This drive train will be used in an older Volvo military vehicle.

You wish to either:
• use the ’03 PCM and existing ’03 tune to run the ’07 engine
• load the ’06 tune you located - into the ’03 PCM
• use the ’03 MAF with the divorced IAT – with either of the above PCM combinations

Will the ’03 PCM with the ’03 tune run the ’07 engine? To accurately answer this you would need OEM type service manuals for the ’07 application, and the ’03 application, to compare PCM pinouts, sensor wiring schematics, and sensor input / output values. You would then need to adapt the wiring harness as necessary – for both the PCM and sensors.

Some sensors may not be compatible, necessitating a purchase. The tables in the ’03 PCM tune would have to be altered as necessary to function accurately with compatible ’07 sensors.

The ’03 MAF you have uses a divorced IAT – similar to early Camaros and Corvettes. All Sierra 1500 pickups from ’99 to ’07 (Classic) with gas engines used an integrated MAF / IAT sensor.

The two ‘03 PCMs you have are compatible with DBC. The question remains, is either compatible with the ’06 tune. Unless you have a Stream Licence, that remains a $100 gamble – if you elect to use the “Test” function of the PCM Flash utility.

You also mentioned perhaps not using a MAF (running in Speed Density) nor a VSS. In a stock configuration the MAF assists with adapting to changing atmospheric conditions. Not running an accurate VSS signal to the PCM may cause idle / driveability issues.

Sometimes it costs more (time and money) to use a collection of parts on hand, rather than purchasing known compatible parts.

I would recommend a trip to your local auto recycler to purchase:
• an integrated MAF / IAT for a ’99 to ’07 (Classic) Sierra / Silverado (don’t use a MAF from a Savana / Express van – they’re smaller and the OEM tune has different MAF values than your ’06 Sierra tune)
• a PCM (service numbers & hardware numbers are in my previous post)

At my local auto recycler PCMs cost around $50, and MAFs cost around $30. Your area may have higher costs – but it remains the “best” option to get you running in the least time, for the least money.

Regards,
Taz

[dgiller]

Thanks again Taz.

A clarification, though it's not actually material: The transmission/TC is actually not from the donor pickup. It's assembled from rebuilt 70's era components. I'm not overly worried about that, however.

Also, I don't care if I have to replace the S10 MAF with a Silverado/Sierra MAF/IAT. I just happen to have an '03 and know it doesn't fit the '07 harness, and figured out that it's because it's a combined MAF/IAT. I hadn't really thought it was likely that the '03 tunes or the '03 MAF would be usable, but I was definitely interested in whether there were any reasons an '06 tune might not work on an '06 PCM.

So under the 'You wish to either', I think it's more a matter of wondering if any of those options are safe. You've given some very good specific reasons why each of those are likely not to be safe, so I'll play it safe and get a later 4.3L PCM.

Your comment about time and money is spot on... though through the magic of forums like these, sometimes we can help each other avoid the pitfalls. So thanks for your help! Something had made me hesitant to go buy a third PCM with two sitting on my shelf... I think it was more about the waste than about the cash per se. But with a good reason not to trust them, I've got no reason getting something else.

I'll go to my local wrecker and get a PCM and MAF.

Thanks everyone for your help! I may be back for help once I start tuning... the truck is a mid-engine forward-control van layout, and the V6 is stuffed into a tunnel that was made for a non-cross-flow 3L straight six. So the intake and exhaust is not going to flow as well as the Silverado, and I'm sure I'll need to do some tuning to get everything running like it ought to.

Cheers,
Dave