[LNF SS/TC] - Stock Internal & BW S252 Turbo


Goblin Guru
This is what you want to disable DFCO in an LNF vato - made this change along with a few catalytic converter adjustments and noticed a material change in reduction of warm-up time and increase in burble after wot.


Mayor West

Goblin Guru
See, this is adding to the confusion. From the few sources I've seen online, you leave the first 3 columns as-is, and turn the 4th column from 15 to 0.

I went for a drive after turning 15 to 0 on mine, and it no longer leaned out after letting off the throttle.

The grid isn't very easy to interpret given that it has no row/column identifiers and it's 0 based on both ends.

Mayor West

Goblin Guru
I think the main thing that's keeping me from comparing mine to yours (right now) is I'm working on a baseline tune for an entirely different air delivery setup (blow-through), I don't want to go picking through your adjustments too much until I get the MAF remotely decent, but yes this is something I've needed to address.

It's gotten a lot more drivable, however the few times I've gotten over the vacuum -> boost threshold, I feel like something is triggered and it backs off. Before switching to a 3" MAF pipe (from 2.5") I was getting DTCs for "MAF out of range", but my previous drives with the 3" piping I got about 3-4psi and it sort of backed off and I didn't get any codes and didn't see in my scan where it occurred.

I'll pay closer attention to the boost areas as I drive it more and more, though.

Mayor West

Goblin Guru
So, to further dive down this rabbit hole - I put zero's in everything and left the 15's column in tact, my car did not appear to have DFCO removed - I was leaning out on throttle release.

I stumbled across this post and the guy explains the cells as such:
"For torque injector disable you put it to all zero except for leave the value of 15 in the far right column only from top to bottom. this will eliminate the injector shut off feature for torque control and the 15's keep it working for dfco."

So it looks like the 0's then 15's eliminates injector shut down for whatever torque control is (traction control?) and that the final column is indeed DFCO according to that dude, as well as a few other posts I read stating 15's to 0 for DFCO.

For the sake of my own personal experience in seeing DFCO appear to be disabled with 15's turned to 0 and not disabled when I leave them as 15's, I'm going to keep it as I originally had it.


I suppose you could turn them all to 0's, though.

Mayor West

Goblin Guru
Going back into tuning for my larger MAF pipe (2.5 to 3"), I originally scaled my MAF 1.44x per the previous discussion in terms of how much larger my MAF tube was from the original one, which resulted in some extremely rich low-throttle driving (.6-.7 lamba).

I changed this to 1.10x and incremented 10% until it idled well enough. I found that 1.3x was a pretty nice spot... so, after the roads dry up I'm going to make multiple files in ~1% increments to see which maf scaling provides the least amount of angry idling & scanning, so like 1.25, 1.26, 1.27, etc etc up through 1.35x.

Also drove around with the above DFCO map (15's to 0) and it appeared to always stay under 1.05 lambda when off throttle, which I'm assuming is disabling DFCO - lotta burbles, too.

I drove to my parents house to show them the running version for the first time, it appeared to drive very well. No big issues or surprises other than oil leaks.


Goblin Guru
Your method of 1% change, and test will work, but it is a slow way to tune. Watching what the engine wants, and going that direction will get you there quicker. Are you able to turn off the short term fuel trims (STFT)? Or are you watching them as you tune?

If the STFT are disabled, (the normal method of tuning)
then you should be able to calculate and log the % errors in the wideband observed AFR versus the electronic control unit, ECU commanded AFR.
These AFR % errors are logged then applied to the table you are tuning.

If the STFT are active while you are tuning,
then you can use them and the long term fuel trims, LTFT, to guide you.
The STFT and LTFT are correcting the errors in the air fuel ratio, AFR. The direction and amount of AFR error is a guide as to which way and how much to adjust the table you are tuning. You should zero out the STFT and LTFT tables before trying the next tune. Otherwise that previous tune's LTFT bias will take many miles (10-30 miles?) of driving to settle down between tunes.

Mayor West

Goblin Guru
I think from previous posts we've concluded that I cannot disable the O2's, force open loop, or exclude STFT's because of the LNF platform.

I'm not trying to get it 100% but I want to get it dialed in as pleasantly as possible before I take it to a professional tuner to be put on the Dyno. I like having some insight into this, so the length of time it takes me to do it isn't really important to me.