411 pcm custom boosted 4.3l application, do i need a custom os for tuner pro

[dave w]

I wonder if an EFI Live Licensed PCM with a Custom 12212156 Operating System could be read with the AVT 852 Interface, then "Cloned" into another '0411 PCM with the AVT 852 Interface?

dave w

[craign27]

It would be possible to read the bin file with avt interface and pcm hammer, loading it into tuner pro may be a problem as the xdf file may not match the modified OS. One would have to try it to see what the tables look like

[craign27]

After sleeping on it i may have a possible solution, would like to know other peoples thoughts who have a little more experience on this than I
1 bar MAP, 2 bar & 3 bar maps all output 0-5v DC(values are different at same pressure) so if i leave the normal 1 bar scale and offset in the calibration it means at atmosphere for the 2 bar sensor the PCM is thinking its 50.5 kpa if i then change my calibration files and move everything thats at 101 kpa to the 50.5 (would also have to move all the other values down) then above the 50.5 kpa will become my boosted readings. (tables would look a little confusing unless you new what has been done)
I tested this on my test bed setup and yes my thoughts are right in that with 2 bar sensor on my pcm was displaying 47kpa at my house, by applying approx 15psi pressure it went to full scale of 105 kpa on my tuner pro dashboard.
I would need to change all my tables that reference the MAP sensor values in the same manor.
I'm using speed density in an engine only pcm as it going into a boat with no emission equipment so i think the following tables Would need to changed accordingly- B0101 Main VE table, B0102 Cranking VE table, Cranking VE barometric multiplier, Key on initial fuel, DFCO map, B3701 injector pulse width, B3605 open loop commanded fuel, B3810 LTFT, B0404 Barometric offset, B6204 knock retard, B6206 Adaptive octane learn gain based on map, Coil dwell time multiplier, C3003 predicted MAP max, C3004 predicted map min, Barometric pressure shift correction.(can't see a table for spark advance referencing MAP, seems strange as with boost need to retard timing a little)
Has anybody done this?

[turbo_bu]

I have not done this on an 0411 PCM, but FWIW, this is the basic 2 bar MAP hack that had been used years ago when we didn't have custom OS's. I know for the old LT1's (EE hack version of PCM's), this was the way to do a boosted setup. There will be a slight difference for the 0411 PCM, but in general your theory is correct.

To keep this a low cost DIY solution, I would do the 2 bar MAP hack and call it a day. As others have stated, if you want to go with an elegrant solution, then EFI Live and HPT's would be the best route.

[craign27]

Thanks for the feedback, nice to know I'm heading in the right direction.
My last stumbling block is spark advance as the tables all reference grams/cyl which looks like an air mass calculation which i'm guessing is using the MAF sensor (i wsn't planning on using one as i was going speed density tune).
So now i'm trying to find how its uses the map sensor for spark correction

[dave w]

Usually MAFless programming will set the MAF into a permanent error, which causes the PCM to use the low octane spark tables. Perhaps copy / paste the high octane spark table into the low octane spark tables.

dave w

[1project2many]

Simply exchanging the MAP with a 2 BAR requires one to change many variables. But it can work. You can adjust tunerpro to display the correct units in your tables and constants to help prevent you from forgetting to scale a MAP value. Then you need to check everything that is MAP related to adjust the value back to stock or back to a reasonable number.

When MAF is in error PCM calculates MAF using primary VE table, RPM, and IAT. VE also plays a part in AE/DE. Different OS's / PCM's are biased more or less toward VE. No matter which OS, correctly tuned VE tables should be considered mandatory.