2 bar tune for Turbo LT1 F-body possible with '93 ECM? DA3

[Skinny Pedal]

The open loop fuel adder, IIRC, is the commanded open loop AFR. Can you post up the file you will be starting with?

[hotrodf1]

Yeah no prob. Modded bin, XDF, and stock bin JIC

The table I'm talking about isn't commanded AFR I don't believe. I think it just adds fuel on top of the VE table, of course only when in open loop. Sort of a PE mode, without going into PE mode. I have that disabled too. Maybe I shouldn't?

The 2 bar MAP came in today. Guess I'm going to see if she'll run NA with the 2 bar MAP.

Still not sure what to do about the Baro update deal. Maybe it won't even matter.BDLD 93 Z28 M6 R34 2 BAR MAP.binDA3.xdf

[hotrodf1]

Hmm, didn't attache like I thought

[Xnke]

Hope you don't have a 4L60E in there.

The reason you can't do this with the 2-bar map isn't fueling. It's that EVERYTHING in the trans code relies and absolutely needs that 1 bar map sensor, or you're gonna have to re-code all the transmission line pressure and shift timing sections. On top of that, you have to overcome the barometric update issue-I have the same issue with the P66 code in the 94/95 V6 computers. I have to run with the barometric update completely disabled, and had to create a new MAP sensor conversion to report accurate pressure, and then create an emulated 1 bar MAP value to pass off to the transmission code. I'm still (two years later) working out the last few bugs of JUST the emulated 1bar MAP sensor, and the small group that started the project had to work in an extremely tight code limit.

The 2-bar sensor does use the same 0-5v range, but it uses a different linear equation to convert from a 0-255 value to the 8-200kpA value. You'll need to find the ADC sample code, hijack the ADC code's output and run it through your new equation, fork if greater than 100kpA so you can set a flag that tells the PCM you're in boost, use the boost tables, and then unset the flag when you drop under 100kpA. At the same time, create an emulated MAP value to send to the T-side of the pcm to allow transmission controls to function, and keep some of the other stuff (air conditioning) working properly. Then, you'll need to create a second set of VE and Spark timing tables to use when the 100kpA flag is set. Then, you'll need to deal with things like the EGR, purge solenoid, baro update, MAP sensor fail mode, etc all still work...even if you are not using them, the PCM code is there and it WILL try to use them. This can cause MAJOR issues, especially the EGR and Baro update problems. EGR will change your spark timing and targeted AFR, and if you were to get a baro update (which will happen immediately upon hitting 100kpA) it would reset the baro pressure to 100kpA, altering your base fuel and your boosted fuel maps.

There is a lot more than just halving/shifting tables around.

[Skinny Pedal]

First post shows LT1/T56 swapped. If purge, egr and other things never run how would they cause issues? This is also the early LT1 ecm.

On the flip side to all this, all the other ones that have been done were all manual trans and have been going strong for years now.

[hotrodf1]

Yes the egr and other emissions stuff have been disabled. I don’t think that will cause any issues.

I’ll never hit what the ecu thinks is 100kpa because that would be 14 psi boost in reality (with 2 bar map). So I don’t think it will update on the fly.

However it is showing a baro reading of 54.36. So last night was first couple passes at a NA tune with the 2 bar. Had to run the cylinder volume up to 1100cc to get close on fuel I guess since the ecu is seeing the air as very light ( which would require less fuel). That gets it running and driving. I can still use injector flow to further modify too if needed.

I need to get the fueling closer so I can get back to open loop. It runs smoother open loop for some reason.

[Xnke]

The baro update can happen any time the PCM would normally do a baro update, regardless of 100kpA, but it will happen automatically at 100kpA. You need to disable that.

How are you retarding your spark?