Tuning the Monster...I hope

[KennyChapman]

First of all, thanks everyone for being so cool and helpful! So I guess I did my project backwards. As an oldschool car guy I built the motor for my 1999 c2500 Suburban first and then hoped it would run on it's original "black box" ECU. The engine is a 496 stroker BBC With custom intake and heads. OEM injectors on a not so OEM fuel system. Anyhow, It looks like my best bet for this thing is to do the Ol' 0411 swap. I already PM'd Lextech, but would love any help that can be offered with a base tune or at least a starting point for one. I am on overload with all the data that is here and it seems that there is little about this particular build of mine. At least I can't seem to find it when searching the forum. I ordered and received a GT dongle from OBDXpro last week and hope to use PCMhammer and Tuner pro for this tuning. Thanks in advance for any help you can send my way.

[dave w]

[KennyChapman]

Thanks for the Welcome! So, progress report. I made it out to the local "you pull it" Junkyard today and picked out two 12200411 PCMs with connectors (In case I ruin one) for $40. I cleaned the gunk off the outside of them and soldered up a bench harness. After some fooling around with drivers and rebooting my PC I got the OBDXpro GT to finally work and was able to save my first BIN file, which I am attaching, in case anyone cares. Now on to find an XDF for it...

[KennyChapman]

I made a lot of progress on this. I completed the swap and once I disabled VATS and changed the VIN it started up. Today I am working on wiring in the 4 PRNDL wires and trying to get the TPS to have a more accurate response. My Throttle body is custom fab by me in order to use the OEM TPS on a dominator intake. I am going to post in this thread the steps/tune I used to get this swap to work on my 8.1 L 496 BBC engine once I have perfected the tune.

[ralmo94]

Today I am working on wiring in the 4 PRNDL wires

I believe I you don't have to wire those in if you change something in the tune, if I remember correctly, in HP Tuners, you would change PRNDL drop down menu to "none", and it will use the range sensor on the transmission.

[KennyChapman]

To get the VE dialed in, you need to fail the MAF sensor so it runs speed density.
Did you adjust the cylinder volume size?
Are your injector settings correct for injectors being used? That's where to start. (From the other thread.)

I think I am getting my butt kicked by this part. I really have no idea what I am doing but I have spent Probably 40 hrs over the last few weeks reading stuff and trying to understand tuning. I did disable MAF. Cylinder size is correct. But I have no idea what to set for fuel injectors. I found some stock flow data as I am using the stock injectors, but I was not able to read my original PCM and have no frame of reference to start from with; Injector voltage correction, Min.Injector pulse, Injector Pulse Width voltage adj., default Injector Pulse Width. The swapped in PCM was from a 5.7L engine and I am way up at 8.1L but still using stock 7.4L vortec L29 injectors.

ralmo94, if you have the ability to look up any of the stock param's on your vehicle( I believe you have the same as mine when it was stock) That would be so awesome.

I didn't see your post until i had already soldered up the harness with the 4 transmission wires. Hardware is super easy for me so I had no trouble with that. I'll post some pictures later.

[bobcratchet555]

injector data for L29 injectors attached (58 psi)

CAVEAT: those will absolutely not be enough to feed that engine. Probably you cheapest upgrade path is to use injectors from an L59, which is the flex fuel version of the LM7. They are 36 lb/hr (at 58psi) and available all over in every junkyard in america

second caveat: this is a tune that i came up with for a customer who was 0411 swapping his L29. The goal was for it to be a copy of a stock L29/4L80e tune, except using an 0411 PCM with the 2002 operating system. Spark, VE, and anything else that was in the L29 tune, was copied over into this tune.

[KennyChapman]

Thanks for this! I assume I should be able to view this with the same xdf I have been using for my 0411 bin.(12208322.xdf) I was wondering if that would be the case, with my stock injectors being too small. The dumb thing is that prior to the engine rebuild i replaced the injectors with New AcDelco ones for $600 or so, so they have about 800 miles on them and I wanted to get more out of them for the $$ spent. Oh well.

[bobcratchet555]

Thanks for this! I assume I should be able to view this with the same xdf I have been using for my 0411 bin.(12208322.xdf) I was wondering if that would be the case, with my stock injectors being too small. The dumb thing is that prior to the engine rebuild i replaced the injectors with New AcDelco ones for $600 or so, so they have about 800 miles on them and I wanted to get more out of them for the $$ spent. Oh well.

this file uses the 12212156 OS, which will require a different xdf. i am sure that there is one available on this site

your stock injectors should at least let it idle and run/drive. BUT - they will likely max out before you see the full potential of a 496 BBC

[ralmo94]

Your stock injectors should be fine below 4k rpm. Stock settings of the express van l31 5.7 tune I compared with l29 stock injectors are about the same at 12 - 14 volts, should be close enough.

As stated the stock ls 30lb injectors are a good idea, as, as far as the tune goes, it's a copy and paste afair.

Log your injector duty to see if you go over 80% and when in the rpm range you do.

[KennyChapman]

So I got to looking at this 12212156 OS and the VE table is very different from the original one from the stock 0411 PCM, which is leaving me confused. The Stock one is fro a 5.7 and the one Bobcratchet provided is stated a being from a 7.4 L The difference is 30 times higher than the original one, which makes me wonder what is happening on the back end of the VEtables. I am not sure if I should modify the VE table that much or if I am going to cause damage if I do. Can anyone help me understand?IMG_20230416_221017.jpg IMG_20230416_221408_1.jpg(original VE numbers in the 1.5 to 2.5 range new provided VE numbers in the 30 to 80 range.
One other question. Am I stuck using OS 12208322 because that is what the PCM came with, or can I Clone it to OS 12212156 with PCM Hammer?

[Thorwon]

So I got to looking at this 12212156 OS and the VE table is very different from the original one from the stock 0411 PCM, which is leaving me confused. The Stock one is fro a 5.7 and the one Bobcratchet provided is stated a being from a 7.4 L The difference is 30 times higher than the original one, which makes me wonder what is happening on the back end of the VEtables. I am not sure if I should modify the VE table that much or if I am going to cause damage if I do. Can anyone help me understand?IMG_20230416_221017.jpg IMG_20230416_221408_1.jpg(original VE numbers in the 1.5 to 2.5 range new provided VE numbers in the 30 to 80 range.
One other question. Am I stuck using OS 12208322 because that is what the PCM came with, or can I Clone it to OS 12212156 with PCM Hammer?

Those tables are NOT the same. They aren't set-up the same, so the values probably aren't interchangeable.
Hopefully somebody will chime in and give you advice on how to fix it. That's a little over my head.

[ralmo94]

Looks like one has rpm as a column and the other as a row. Doesn't really matter. VE is determined by the cam and intake and exhaust flow. Only way to get it right is log and tune with MAF failed. You should set cylinder size then log it, the VE is mostly used for when air flow changes happen to fast for the MAF to read accurate, think of like accel enrich. I would run it with just cylinder size changed to the correct size, and if fuel trims are off far, change the lb per hr of the injector size to get it a little closer, then fail the MAF and log and tune your VE table, then turn MAF back on. I always save file as, and give a new file name, in case you you to roll back changes, it's real easy.

[ralmo94]

One other question. Am I stuck using OS 12208322 because that is what the PCM came with, or can I Clone it to OS 12212156 with PCM Hammer?

You should be able to change to 2156 os, do a full write with a 2156 bin file and it should work fine.

[KennyChapman]

Thank Gentlemen. I think I will flash the 2156 OS to the truck and see if it is better than the hack job I created from the 8322 OS. Thanks ralmo for the suggestion on how to go about tuning.