Tuning LS1 Superchared 02 TA with speed density and o2

[RamAir]

I have an supercharged 02 Trans Am that is speed density tuned with a 2 bar MAP. I would like to be able to use the 02 sensors in closed loop with the tune. How is this accomplished? Do you activate the 02 by enabling them by setting the closed loop temp enable to around 92F? What tells the 02 to turn off when in full throttle? Can you have an active maf with a 2 bar MAP set-up or is this only a speed density parameter?

[joecar]

Enable Closed Loop and Trimming (see B3801, B4205).

Whenever the PCM has to command other than stoich, it stops learning the trim, but it still applies the last trim if it is positive.

At WOT the PE table should be enabling.


If you run CL, then when PE enables, the PE table is the only active commanded fuel table.

If you run OL, then when PE enables, the PE table and the OLFA tables are both active, the PCM selects the richer (at the current operating point).


I don't understand your last question... (you can run a MAF with 2-bar if the MAF's PCM limit is not exceeded).

[RamAir]

So when the car is running in closed loop, where do the LTFT values get stored (I assume that the PE table never gets overwritten). How does OLFA (Open Loop Fuel Air - I assume) When the engines makes boost, I do exceed the MAF limit, that was why the tuner deactivated it. So, if I activate it again, what happens when the values are exceeded- does it default to the PE table. What I am trying to accomplish is consistent good AF ratios at idle and part throttle speeds - like expressway. Then when I get into it (up to 12 lbs of boost), have the PE table take over.

[joecar]

The PCM has in memory a pair of matrixes for storing the LTFT's...

connect the V7 scantool to the PCM, and go Calibration->LTFT's (or similar)...

it shows a 4x4 matrix (MAPxRPM) containing the learned LTFT's for each bank.

[joecar]

The PE table only gets written by you using the tunetool editor.

When the operating point exceeds the axis range of any particular table, the last cell on that axis is the value used.

IDK why you're tuner didn't... did he maybe scale...?

If you enable the MAF and you exceed the PCM's MAF range, then the MAF value will be pegged at the PCM's MAF limit (512 g/s) until the operating point comes back down.

PE is independent of (and unreleated to) VE and MAF.

[ VE and MAF are air tables; OLFA and PE are fueling tables ]


Idle and part throttle are tuned the same way they always have.

PE should enable whenever engine load becomes significant, e.g. look at the 2002 Camaro tune file... with boost you want PE to enable easier than that.

[joecar]

If you want to have boost, then a COS will make tuning easier.

[RamAir]

OK, so if I enable the MAF again, then the O2 & MAF will enable good AFR during my normal driving. When I get into the throttle, and the MAF gets pegged, then the PE table takes over (Boost VE table) and the PE ensures I maintain my 11.7 to 1 AFR? So, with the MAF turned back on, does it use the MAF airflow values alone or in combination with the main VE table? How do you activate the MAF again- I can't seem to find where to do this; the MAF tab shows what looks to be correct values (pegs at 67.7 Lb/min). Also, what is COS?

[joecar]

PE determines AFR when it becomes enabled (at any significant load) whether MAF pegs or not... (i.e. PE does not take over after MAF pegs)...

when the MAF pegs and rpm keeps increasing, the PCM undercalculates cylinder airmass, so you run the danger of running significantly leaner than 11.7 AFR.


VE/MAF are independent and exclusive of PE/OLFA.


Do you already run a COS...? (Boost VE table)


Above 4000 rpm, MAF is exclusive.
Below 4000 rpm, MAF is used for steady state airflow, VE is used for transient airflow.


MAF is enabled by setting sane/stock values for C2901-3 and observing thatMAF DTC's do not trigger (implying the MAF DTC's are enabled in C6001).

[joecar]

More info, see post #4 here: Summary-Notes (http://forum.efilive.com/showthread.php?14188-Summary-Notes)